Related
There're plenty of different CSS shapes over at CSS Tricks - Shapes of CSS and I'm particularly puzzled with a triangle:
#triangle-up {
width: 0;
height: 0;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 100px solid red;
}
<div id="triangle-up"></div>
How and why does it work?
CSS Triangles: A Tragedy in Five Acts
As alex said, borders of equal width butt up against each other at 45 degree angles:
When you have no top border, it looks like this:
Then you give it a width of 0...
...and a height of 0...
...and finally, you make the two side borders transparent:
That results in a triangle.
The borders use an angled edge where they intersect (45° angle with equal width borders, but changing the border widths can skew the angle).
div {
width: 60px;
border-width: 30px;
border-color: red blue green yellow;
border-style: solid;
}
<div></div>
Have a look to the jsFiddle.
By hiding certain borders, you can get the triangle effect (as you can see above by making the different portions different colours). transparent is often used as an edge colour to achieve the triangle shape.
Start with a basic square and borders. Each border will be given a different color so we can tell them apart:
.triangle {
border-color: yellow blue red green;
border-style: solid;
border-width: 200px 200px 200px 200px;
height: 0px;
width: 0px;
}
<div class="triangle"></div>
which gives you this:
But there's no need for the top border, so set its width to 0px. Now our border-bottom of 200px will make our triangle 200px tall.
.triangle {
border-color: yellow blue red green;
border-style: solid;
border-width: 0px 200px 200px 200px;
height: 0px;
width: 0px;
}
<div class="triangle"></div>
and we will get this:
Then to hide the two side triangles, set the border-color to transparent. Since the top-border has been effectively deleted, we can set the border-top-color to transparent as well.
.triangle {
border-color: transparent transparent red transparent;
border-style: solid;
border-width: 0px 200px 200px 200px;
height: 0px;
width: 0px;
}
<div class="triangle"></div>
finally we get this:
Different approach:
CSS3 triangles with transform rotate
Triangular shape is pretty easy to make using this technique. For people who prefer to see an animation explaining how this technique works here it is :
Link to the ANIMATION : How to make a CSS3 triangle.
And DEMO : CSS3 triangles made with transform rotate.
Otherwise, here is detailed explanation in 4 acts (this is not a tragedy) of how to make an isosceles right-angled triangle with one element.
Note 1 : for non isosceles triangles and fancy stuff, you can see step 4.
Note 2 : in the following snippets, the vendor prefixes aren't included. they are included in the codepen demos.
Note 3 : the HTML for the following explanation is always : <div class="tr"></div>
STEP 1 : Make a div
Easy, just make sure that width = 1.41 x height. You may use any techinque (see here) including the use of percentages and padding-bottom to maintain the aspect ratio and make a responsive triangle. In the following image, the div has a golden yellow border.
In that div, insert a pseudo element and give it 100% width and height of parent. The pseudo element has a blue background in the following image.
At this point, we have this CSS :
.tr {
width: 30%;
padding-bottom: 21.27%; /* = width / 1.41 */
position: relative;
}
.tr: before {
content: '';
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
background: #0079C6;
}
STEP 2 : Let's rotate
First, most important : define a transform origin. The default origin is in the center of the pseudo element and we need it at the bottom left. By adding this CSS to the pseudo element :
transform-origin:0 100%; or transform-origin: left bottom;
Now we can rotate the pseudo element 45 degrees clockwise with transform : rotate(45deg);
At this point, we have this CSS :
.tr {
width: 30%;
padding-bottom: 21.27%; /* = width / 1.41 */
position: relative;
}
.tr:before {
content: '';
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
background: #0079C6;
transform-origin: 0 100%;
transform: rotate(45deg);
}
STEP 3 : hide it
To hide the unwanted parts of the pseudo element (everything that overflows the div with the yellow border) you just need to set overflow:hidden; on the container. after removing the yellow border, you get... a TRIANGLE! :
DEMO
CSS :
.tr {
width: 30%;
padding-bottom: 21.27%; /* = width / 1.41 */
position: relative;
overflow: hidden;
}
.tr:before {
content: '';
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
background-color: #0079C6;
transform-origin: 0 100%;
transform: rotate(45deg);
}
STEP 4 : go further...
As shown in the demo, you can customize the triangles :
Make them thinner or flatter by playing with skewX().
Make them point left, right or any other direction by playing with the transform origin and rotation direction.
Make some reflexion with 3D transform property.
Give the triangle borders
Put an image inside the triangle
Much more... Unleash the powers of CSS3!
Why use this technique?
Triangle can easily be responsive.
You can make a triangle with border.
You can maintain the boundaries of the triangle. This means that you can trigger the hover state or click event only when the cursor is inside the triangle. This can become very handy in some situations like this one where each triangle can't overlay its neighbours so each triangle has its own hover state.
You can make some fancy effects like reflections.
It will help you understand 2d and 3d transform properties.
Why not use this technique?
The main drawback is the browser compatibility, the 2d transform properties are supported by IE9+ and therefore you can't use this technique if you plan on supporting IE8. See CanIuse for more info. For some fancy effects using 3d transforms like the reflection browser support is IE10+ (see canIuse for more info).
You don't need anything responsive and a plain triangle is fine for you then you should go for the border technique explained here : better browser compatibility and easier to understand thanks to the amazing posts here.
Here is an animation in JSFiddle I created for demonstration.
Also see snippet below.
This is an Animated GIF made from a Screencast
transforms = [
{'border-left-width' :'30', 'margin-left': '70'},
{'border-bottom-width' :'80'},
{'border-right-width' :'30'},
{'border-top-width' :'0', 'margin-top': '70'},
{'width' :'0'},
{'height' :'0', 'margin-top': '120'},
{'borderLeftColor' :'transparent'},
{'borderRightColor' :'transparent'}
];
$('#a').click(function() {$('.border').trigger("click");});
(function($) {
var duration = 1000
$('.border').click(function() {
for ( var i=0; i < transforms.length; i++ ) {
$(this)
.animate(transforms[i], duration)
}
}).end()
}(jQuery))
.border {
margin: 20px 50px;
width: 50px;
height: 50px;
border-width: 50px;
border-style: solid;
border-top-color: green;
border-right-color: yellow;
border-bottom-color: red;
border-left-color: blue;
cursor: pointer
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script src="https://code.jquery.com/color/jquery.color-2.1.2.min.js"></script>
Click it!<br>
<div class="border"></div>
Random version
/**
* Randomize array element order in-place.
* Using Durstenfeld shuffle algorithm.
*/
function shuffleArray(array) {
for (var i = array.length - 1; i > 0; i--) {
var j = Math.floor(Math.random() * (i + 1));
var temp = array[i];
array[i] = array[j];
array[j] = temp;
}
return array;
}
transforms = [
{'border-left-width' :'30', 'margin-left': '70'},
{'border-bottom-width' :'80'},
{'border-right-width' :'30'},
{'border-top-width' :'0', 'margin-top': '70'},
{'width' :'0'},
{'height' :'0'},
{'borderLeftColor' :'transparent'},
{'borderRightColor' :'transparent'}
];
transforms = shuffleArray(transforms)
$('#a').click(function() {$('.border').trigger("click");});
(function($) {
var duration = 1000
$('.border').click(function() {
for ( var i=0; i < transforms.length; i++ ) {
$(this)
.animate(transforms[i], duration)
}
}).end()
}(jQuery))
.border {
margin: 50px;
width: 50px;
height: 50px;
border-width: 50px;
border-style: solid;
border-top-color: green;
border-right-color: yellow;
border-bottom-color: red;
border-left-color: blue;
cursor: pointer
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script src="https://code.jquery.com/color/jquery.color-2.1.2.min.js"></script>
Click it!<br>
<div class="border"></div>
All at once version
$('#a').click(function() {$('.border').trigger("click");});
(function($) {
var duration = 1000
$('.border').click(function() {
$(this)
.animate({'border-top-width': 0 ,
'border-left-width': 30 ,
'border-right-width': 30 ,
'border-bottom-width': 80 ,
'width': 0 ,
'height': 0 ,
'margin-left': 100,
'margin-top': 150,
'borderTopColor': 'transparent',
'borderRightColor': 'transparent',
'borderLeftColor': 'transparent'}, duration)
}).end()
}(jQuery))
.border {
margin: 50px;
width: 50px;
height: 50px;
border-width: 50px;
border-style: solid;
border-top-color: green;
border-right-color: yellow;
border-bottom-color: red;
border-left-color: blue;
cursor: pointer
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script src="https://code.jquery.com/color/jquery.color-2.1.2.min.js"></script>
Click it!<br>
<div class="border"></div>
Lets say we have the following div:
<div id="triangle" />
Now Edit the CSS step-by-step, so you will get clear idea what is happening around
STEP 1:
JSfiddle Link:
#triangle {
background: purple;
width :150px;
height:150PX;
border-left: 50px solid black ;
border-right: 50px solid black;
border-bottom: 50px solid black;
border-top: 50px solid black;
}
This is a simple div. With a very simple CSS. So a layman can understand. Div has dimensions 150 x 150 pixels with the border 50 pixels. The image is attached:
STEP 2: JSfiddle Link:
#triangle {
background: purple;
width :150px;
height:150PX;
border-left: 50px solid yellow ;
border-right: 50px solid green;
border-bottom: 50px solid red;
border-top: 50px solid blue;
}
Now I just changed the border-color of all 4 sides. The image is attached.
STEP:3 JSfiddle Link:
#triangle {
background: purple;
width :0;
height:0;
border-left: 50px solid yellow ;
border-right: 50px solid green;
border-bottom: 50px solid red;
border-top: 50px solid blue;
}
Now I just changed the height & width of div from 150 pixels to zero. The image is attached
STEP 4: JSfiddle:
#triangle {
background: purple;
width :0px;
height:0px;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 50px solid red;
border-top: 50px solid transparent;
}
Now I have made all the borders transparent apart from the bottom border. The image is attached below.
STEP 5: JSfiddle Link:
#triangle {
background: white;
width :0px;
height:0px;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 50px solid red;
border-top: 50px solid transparent;
}
Now I just changed the background color to white. The image is attached.
Hence we got the triangle we needed.
And now something completely different...
Instead of using css tricks don't forget about solutions as simple as html entities:
▲
Result:
▲
See: What are the HTML entities for up and down triangles?
Consider the below triangle
.triangle {
border-bottom:15px solid #000;
border-left:10px solid transparent;
border-right:10px solid transparent;
width:0;
height:0;
}
This is what we are given:
Why it came out in this shape? The below diagram explains the dimensions, note that 15px was used for the bottom border and 10px was used for left and right.
It's pretty easy to make a right-angle triangle also by removing the right border.
Taking it one step further, using css based on this I added arrows to my back and next buttons (yes I know its not 100% cross-browser, but slick none the less).
.triangle {
width: 0;
height: 0;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 100px solid red;
margin:20px auto;
}
.triangle-down {
border-bottom:none;
border-top: 100px solid red;
}
.triangle-left {
border-left:none;
border-right: 100px solid red;
border-bottom: 50px solid transparent;
border-top: 50px solid transparent;
}
.triangle-right {
border-right:none;
border-left: 100px solid red;
border-bottom: 50px solid transparent;
border-top: 50px solid transparent;
}
.triangle-after:after {
width: 0;
height: 0;
border-left: 5px solid transparent;
border-right: 5px solid transparent;
border-bottom: 5px solid red;
margin:0 5px;
content:"";
display:inline-block;
}
.triangle-after-right:after {
border-right:none;
border-left: 5px solid blue;
border-bottom: 5px solid transparent;
border-top: 5px solid transparent;
}
.triangle-before:before {
width: 0;
height: 0;
border-left: 5px solid transparent;
border-right: 5px solid transparent;
border-bottom: 5px solid blue;
margin:0 5px;
content:"";
display:inline-block;
}
.triangle-before-left:before {
border-left:none;
border-right: 5px solid blue;
border-bottom: 5px solid transparent;
border-top: 5px solid transparent;
}
<div class="triangle"></div>
<div class="triangle triangle-down"></div>
<div class="triangle triangle-left"></div>
<div class="triangle triangle-right"></div>
<a class="triangle-before triangle-before-left" href="#">Back</a>
<a class="triangle-after triangle-after-right" href="#">Next</a>
CSS clip-path
This is something I feel this question has missed; clip-path
clip-path in a nutshell
Clipping, with the clip-path property, is akin to cutting a shape (like a circle or a pentagon) from a rectangular piece of paper. The property belongs to the “CSS Masking Module Level 1” specification. The spec states, “CSS masking provides two means for partially or fully hiding portions of visual elements: masking and clipping”.
Extract from Smashing Magazine
clip-path will use the element itself rather than its borders to cut the shape you specify in its parameters. It uses a super simple percentage based co-ordinate system which makes editing it very easy and means you can pick it up and create weird and wonderful shapes in a matter of minutes.
Triangle Shape Example
div {
-webkit-clip-path: polygon(50% 0%, 0% 100%, 100% 100%);
clip-path: polygon(50% 0%, 0% 100%, 100% 100%);
background: red;
width: 100px;
height: 100px;
}
<div></div>
Downside
It does have a major downside at the moment, one being it's major lack of support, only really being covered within -webkit- browsers and having no support on IE and only very partial in FireFox.
Resources
Here are some useful resources and material to help better understand clip-path and also start creating your own.
Clippy - A clip-path generator
The W3C Candidate Recommendation File
MDN clip-path documentation
clip-path Browser Support
Different approach. With linear gradient (for IE, only IE 10+).
You can use any angle:
.triangle {
margin: 50px auto;
width: 100px;
height: 100px;
/* linear gradient */
background: -moz-linear-gradient(-45deg, rgba(255,0,0,0) 0%, rgba(255,0,0,0) 50%, rgba(255,0,0,1) 50%, rgba(255,0,0,1) 100%);
/* FF3.6+ */
background: -webkit-gradient(linear, left top, right bottom, color-stop(0%,rgba(255,0,0,0)), color-stop(50%,rgba(255,0,0,0)), color-stop(50%,rgba(255,0,0,1)), color-stop(100%,rgba(255,0,0,1)));
/* Chrome,Safari4+ */
background: -webkit-linear-gradient(-45deg, rgba(255,0,0,0) 0%,rgba(255,0,0,0) 50%,rgba(255,0,0,1) 50%,rgba(255,0,0,1) 100%);
/* Chrome10+,Safari5.1+ */
background: -o-linear-gradient(-45deg, rgba(255,0,0,0) 0%,rgba(255,0,0,0) 50%,rgba(255,0,0,1) 50%,rgba(255,0,0,1) 100%);
/* Opera 11.10+ */
background: -ms-linear-gradient(-45deg, rgba(255,0,0,0) 0%,rgba(255,0,0,0) 50%,rgba(255,0,0,1) 50%,rgba(255,0,0,1) 100%);
/* IE10+ */
background: linear-gradient(135deg, rgba(255,0,0,0) 0%,rgba(255,0,0,0) 50%,rgba(255,0,0,1) 50%,rgba(255,0,0,1) 100%);
/* W3C */;
}
<div class="triangle"></div>
Here is jsfiddle
OK, this triangle will get created because of the way that borders of the elements work together in HTML and CSS...
As we usually use 1 or 2px borders, we never notice that borders make a 45° angles to each others with the same width and if the width changes, the angle degree get changed as well, run the CSS code I created below:
.triangle {
width: 100px;
height: 100px;
border-left: 50px solid black;
border-right: 50px solid black;
border-bottom: 100px solid red;
}
<div class="triangle">
</div>
Then in the next step, we don't have any width or height, something like this:
.triangle {
width: 0;
height: 0;
border-left: 50px solid black;
border-right: 50px solid black;
border-bottom: 100px solid red;
}
<div class="triangle">
</div>
And now we make the left and right borders invisible to make our desirable triangle as below:
.triangle {
width: 0;
height: 0;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 100px solid red;
}
<div class="triangle"></div>
If you not willing to run the snippet to see the steps, I've created an image sequence to have a look at all steps in one image:
This is an old question, but I think will worth it to share how to create an arrow using this triangle technique.
Step 1:
Lets create 2 triangles, for the second one we will use the :after pseudo class and position it just below the other:
.arrow{
width: 0;
height: 0;
border-radius: 50px;
display: inline-block;
position: relative;
}
.arrow:after{
content: "";
width: 0;
height: 0;
position: absolute;
}
.arrow-up{
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 50px solid #333;
}
.arrow-up:after{
top: 5px;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 50px solid #ccc;
right: -50px;
}
<div class="arrow arrow-up"> </div>
Step 2
Now we just have to set the predominant border color of the second triangle to the same color of the background:
.arrow{
width: 0;
height: 0;
border-radius: 50px;
display: inline-block;
position: relative;
}
.arrow:after{
content: "";
width: 0;
height: 0;
position: absolute;
}
.arrow-up{
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 50px solid #333;
}
.arrow-up:after{
top: 5px;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 50px solid #fff;
right: -50px;
}
<div class="arrow arrow-up"> </div>
Fiddle with all the arrows:
http://jsfiddle.net/tomsarduy/r0zksgeu/
If you want to apply border to the triangle read this: Create a triangle with CSS?
Almost all the answers focus on the triangle built using border so I am going to elaborate the linear-gradient method (as started in the answer of #lima_fil).
Using a degree value like 45° will force us to respect a specific ratio of height/width in order to obtain the triangle we want and this won't be responsive:
.tri {
width:100px;
height:100px;
background:linear-gradient(45deg, transparent 49.5%,red 50%);
/*To illustrate*/
border:1px solid;
}
Good one
<div class="tri"></div>
bad one
<div class="tri" style="width:150px"></div>
bad one
<div class="tri" style="height:30px"></div>
Instead of doing this we should consider predefined values of direction like to bottom, to top, etc. In this case we can obtain any kind of triangle shape while keeping it responsive.
1) Rectangle triangle
To obtain such triangle we need one linear-gradient and a diagonal direction like to bottom right, to top left, to bottom left, etc
.tri-1,.tri-2 {
display:inline-block;
width:100px;
height:100px;
background:linear-gradient(to bottom left, transparent 49.5%,red 50%);
border:1px solid;
animation:change 2s linear infinite alternate;
}
.tri-2 {
background:linear-gradient(to top right, transparent 49.5%,red 50%);
border:none;
}
#keyframes change {
from {
width:100px;
height:100px;
}
to {
height:50px;
width:180px;
}
}
<div class="tri-1"></div>
<div class="tri-2"></div>
2) isosceles triangle
For this one we will need 2 linear-gradient like above and each one will take half the width (or the height). It's like we create a mirror image of the first triangle.
.tri {
display:inline-block;
width:100px;
height:100px;
background-image:
linear-gradient(to bottom right, transparent 49.5%,red 50%),
linear-gradient(to bottom left, transparent 49.5%,red 50%);
background-size:50.3% 100%; /* I use a value slightly bigger than 50% to avoid having a small gap between both gradient*/
background-position:left,right;
background-repeat:no-repeat;
animation:change 2s linear infinite alternate;
}
#keyframes change {
from {
width:100px;
height:100px;
}
to {
height:50px;
width:180px;
}
}
<div class="tri"></div>
3) equilateral triangle
This one is a bit tricky to handle as we need to keep a relation between the height and width of the gradient. We will have the same triangle as above but we will make the calculation more complex in order to transform the isosceles triangle to an equilateral one.
To make it easy, we will consider that the width of our div is known and the height is big enough to be able to draw our triangle inside (height >= width).
We have our two gradient g1 and g2, the blue line is the width of the div w and each gradient will have 50% of it (w/2) and each side of the triangle sould be equal to w. The green line is the height of both gradient hg and we can easily obtain the formula below:
(w/2)² + hg² = w² ---> hg = (sqrt(3)/2) * w ---> hg = 0.866 * w
We can rely on calc() in order to do our calculation and to obtain the needed result:
.tri {
--w:100px;
width:var(--w);
height:100px;
display:inline-block;
background-image:
linear-gradient(to bottom right, transparent 49.5%,red 50%),
linear-gradient(to bottom left, transparent 49.5%,red 50%);
background-size:calc(var(--w)/2 + 0.5px) calc(0.866 * var(--w));
background-position:
left bottom,right bottom;
background-repeat:no-repeat;
}
<div class="tri"></div>
<div class="tri" style="--w:80px"></div>
<div class="tri" style="--w:50px"></div>
Another way is to control the height of div and keep the syntax of gradient easy:
.tri {
--w:100px;
width:var(--w);
height:calc(0.866 * var(--w));
display:inline-block;
background:
linear-gradient(to bottom right, transparent 49.8%,red 50%) left,
linear-gradient(to bottom left, transparent 49.8%,red 50%) right;
background-size:50.2% 100%;
background-repeat:no-repeat;
}
<div class="tri"></div>
<div class="tri" style="--w:80px"></div>
<div class="tri" style="--w:50px"></div>
4) Random triangle
To obtain a random triangle, it's easy as we simply need to remove the condition of 50% of each one BUT we should keep two condition (both should have the same height and the sum of both width should be 100%).
.tri-1 {
width:100px;
height:100px;
display:inline-block;
background-image:
linear-gradient(to bottom right, transparent 50%,red 0),
linear-gradient(to bottom left, transparent 50%,red 0);
background-size:20% 60%,80% 60%;
background-position:
left bottom,right bottom;
background-repeat:no-repeat;
}
<div class="tri-1"></div>
But what if we want to define a value for each side? We simply need to do calculation again!
Let's define hg1 and hg2 as the height of our gradient (both are equal to the red line) then wg1 and wg2 as the width of our gradient (wg1 + wg2 = a). I will not going to detail the calculation but at then end we will have:
wg2 = (a²+c²-b²)/(2a)
wg1 = a - wg2
hg1 = hg2 = sqrt(b² - wg1²) = sqrt(c² - wg2²)
Now we have reached the limit of CSS as even with calc() we won't be able to implement this so we simply need to gather the final result manually and use them as fixed size:
.tri {
--wg1: 20px;
--wg2: 60px;
--hg:30px;
width:calc(var(--wg1) + var(--wg2));
height:100px;
display:inline-block;
background-image:
linear-gradient(to bottom right, transparent 49.5%,red 50%),
linear-gradient(to bottom left, transparent 49.5%,red 50%);
background-size:var(--wg1) var(--hg),var(--wg2) var(--hg);
background-position:
left bottom,right bottom;
background-repeat:no-repeat;
}
<div class="tri" ></div>
<div class="tri" style="--wg1:80px;--wg2:60px;--hg:100px;" ></div>
Bonus
We should not forget that we can also apply rotation and/or skew and we have more option to obtain more triangle:
.tri {
--wg1: 20px;
--wg2: 60px;
--hg:30px;
width:calc(var(--wg1) + var(--wg2) - 0.5px);
height:100px;
display:inline-block;
background-image:
linear-gradient(to bottom right, transparent 49%,red 50%),
linear-gradient(to bottom left, transparent 49%,red 50%);
background-size:var(--wg1) var(--hg),var(--wg2) var(--hg);
background-position:
left bottom,right bottom;
background-repeat:no-repeat;
}
<div class="tri" ></div>
<div class="tri" style="transform:skewY(25deg)"></div>
<div class="tri" style="--wg1:80px;--wg2:60px;--hg:100px;" ></div>
<div class="tri" style="--wg1:80px;--wg2:60px;--hg:100px;transform:rotate(20deg)" ></div>
And of course we should keep in mind the SVG solution which can be more suitable in some situation:
svg {
width:100px;
height:100px;
}
polygon {
fill:red;
}
<svg viewBox="0 0 100 100"><polygon points="0,100 0,0 100,100" /></svg>
<svg viewBox="0 0 100 100"><polygon points="0,100 50,0 100,100" /></svg>
<svg viewBox="0 0 100 100"><polygon points="0,100 50,23 100,100" /></svg>
<svg viewBox="0 0 100 100"><polygon points="20,60 50,43 80,100" /></svg>
SASS (SCSS) triangle mixin
I wrote this to make it easier (and DRY) to automatically generate a CSS triangle:
// Triangle helper mixin (by Yair Even-Or)
// #param {Direction} $direction - either `top`, `right`, `bottom` or `left`
// #param {Color} $color [currentcolor] - Triangle color
// #param {Length} $size [1em] - Triangle size
#mixin triangle($direction, $color: currentcolor, $size: 1em) {
$size: $size/2;
$transparent: rgba($color, 0);
$opposite: (top:bottom, right:left, left:right, bottom:top);
content: '';
display: inline-block;
width: 0;
height: 0;
border: $size solid $transparent;
border-#{map-get($opposite, $direction)}-color: $color;
margin-#{$direction}: -$size;
}
use-case example:
span {
#include triangle(bottom, red, 10px);
}
Playground page
Important note: if the triangle seems pixelated in some browsers, try one of the methods described here.
If you want to play around with border-size, width and height and see how those can create different shapes, try this:
const sizes = [32, 32, 32, 32];
const triangle = document.getElementById('triangle');
function update({ target }) {
let index = null;
if (target) {
index = parseInt(target.id);
if (!isNaN(index)) {
sizes[index] = target.value;
}
}
window.requestAnimationFrame(() => {
triangle.style.borderWidth = sizes.map(size => `${ size }px`).join(' ');
if (isNaN(index)) {
triangle.style[target.id] = `${ target.value }px`;
}
});
}
document.querySelectorAll('input').forEach(input => {
input.oninput = update;
});
update({});
body {
margin: 0;
min-height: 100vh;
display: flex;
justify-content: center;
align-items: center;
overflow: hidden;
}
#triangle {
border-style: solid;
border-color: yellow magenta blue black;
background: cyan;
height: 0px;
width: 0px;
}
#controls {
position: fixed;
bottom: 0;
left: 0;
right: 0;
background: white;
display: flex;
box-shadow: 0 0 32px rgba(0, 0, 0, .125);
}
#controls > div {
position: relative;
width: 25%;
padding: 8px;
box-sizing: border-box;
display: flex;
}
input {
margin: 0;
width: 100%;
position: relative;
}
<div id="triangle" style="border-width: 32px 32px 32px 32px;"></div>
<div id="controls">
<div><input type="range" min="0" max="128" value="32" id="0" /></div>
<div><input type="range" min="0" max="128" value="32" id="1" /></div>
<div><input type="range" min="0" max="128" value="32" id="2" /></div>
<div><input type="range" min="0" max="128" value="32" id="3" /></div>
<div><input type="range" min="0" max="128" value="0" id="width" /></div>
<div><input type="range" min="0" max="128" value="0" id="height" /></div>
</div>
here is another fiddle:
.container:after {
position: absolute;
right: 0;
content: "";
margin-right:-50px;
margin-bottom: -8px;
border-width: 25px;
border-style: solid;
border-color: transparent transparent transparent #000;
width: 0;
height: 0;
z-index: 10;
-webkit-transition: visibility 50ms ease-in-out,opacity 50ms ease-in-out;
transition: visibility 50ms ease-in-out,opacity 50ms ease-in-out;
bottom: 21px;
}
.container {
float: left;
margin-top: 100px;
position: relative;
width: 150px;
height: 80px;
background-color: #000;
}
.containerRed {
float: left;
margin-top: 100px;
position: relative;
width: 100px;
height: 80px;
background-color: red;
}
https://jsfiddle.net/qdhvdb17/
Others have already explained this well. Let me give you an animation which will explain this quickly: http://codepen.io/chriscoyier/pen/lotjh
Here is some code for you to play with and learn the concepts.
HTML:
<html>
<body>
<div id="border-demo">
</div>
</body>
</html>
CSS:
/*border-width is border thickness*/
#border-demo {
background: gray;
border-color: yellow blue red green;/*top right bottom left*/
border-style: solid;
border-width: 25px 25px 25px 25px;/*top right bottom left*/
height: 50px;
width: 50px;
}
Play with this and see what happens. Set height and width to zero. Then remove top border and make left and right transparent, or just look at the code below to make a css triangle:
#border-demo {
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 100px solid blue;
}
I know this is an old one, but I'd like to add to this discussion that There are at least 5 different methods for creating a triangle using HTML & CSS alone.
Using borders
Using linear-gradient
Using conic-gradient
Using
transform and overflow
Using clip-path
I think that all have been covered here except for method 3, using the conic-gradient, so I will share it here:
.triangle{
width: 40px;
height: 40px;
background: conic-gradient(at 50% 50%,transparent 135deg,green 0,green 225deg, transparent 0);
}
<div class="triangle"></div>
use clip-path: polygon(50% 0%, 100% 100%, 0% 100%); for creating easy to Triangle
<div class="triangle"></div>
.triangle{width:200px; height:200px;background:#000;clip-path: polygon(50% 0%, 100% 100%, 0% 100%);}
After reading through the other answers here I see there are great explanations as to why the CSS triangle works the way it does. I would consider it to be somewhat of a trick, versus something that you could apply generically.
For something that's easier to read and maintain, I would recommend you define your geometry in SVG.
Then you can convert that SVG using data uri by adding the data:image/svg+xml, prefix. As a data uri, it can now be used as a background-image in a CSS. Because the SVG is in clear text, you can readily make updates to the geometry, stroke, and fill color.
div.tri {
width: 100px;
height: 100px;
display: inline-block;
background-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32"><path fill="red" d="M31.345 29H1.655L16.5 1.96z"/></svg>');
}
<div>
<div class="tri"></div>
<div class="tri"></div>
<div class="tri"></div>
</div>
Try This:-
.triangle {
border-color: transparent transparent red transparent;
border-style: solid;
border-width: 0px 200px 200px 200px;
height: 0px;
width: 0px;
}
<div class="triangle"></div>
clip-path has the best result for me - works great for divs/containers with and without fixed dimensions:
.triangleContainer{
position: relative;
width: 500px;
height: 500px;
}
.triangleContainer::before{
content: "";
position: absolute;
background:blue;
top: 0;
left: 0;
width: 100%;
height: 100%;
clip-path: polygon(50% 0, 0 100%, 100% 100%);
}
I want my <div> to have a bottom border which starts from a distance away from the left. It's like:
abc
^^^^^^^^^^
where ^ stands for a piece of border.
I achieved this using border-image. I set a border-image to a linear-gradient() image, which starts transparent, and becomes gray from some pixels.
<style>
div {
width: 200px;
border-top-style: none;
border-bottom-style: solid;
border-width: 1px;
border-image: linear-gradient(to right,
transparent 0,
transparent 1em,
lightgray 1em,
lightgray 100%) 100% 1;
}
</style>
<div>abc</div>
Now the new requirement is to add a 1px white line right below the existing line to mimic a 3d effect. I thought I could simply add a vertical gradient to the border image, but I don't know how to do it.
Instead of border consider multiple background. I used different colors to better see the result:
.box {
width: 200px;
background:
linear-gradient(blue, blue) 1em 100%/ 100% 1px no-repeat,
linear-gradient(red, red) 1em 100%/ 100% 2px no-repeat;
}
<div class="box">abc</div>
You can Achive it with box-shadow
If you are using display: flex to your div you should position pseudo after element using position: absoute
See this example:
body {
background-color: lightgreen;
}
div {
display: flex;
position: relative;
}
div:after {
content: "";
position: absolute;
bottom: 0;
left: 0;
display: block;
width: 200px;
height: 1px;
box-shadow: 10px 1px 0 0 lightgray, 10px 2px 0 0 white;
}
<div>abc</div>
<div>edf</div>
So I know how to do a basic box shadow with CSS3. You can see that in the top of the graphic below.
The effect I'm trying to achieve is a 3D box shadow, as shown in the bottom of the graphic below.
Any ideas on how to do this with CSS3 box shadows?
Unfortunately box shadows are effectively just flat layers. However you can apply multiple box shadows to create this effect.
.box-shadow-3d{
box-shadow: 1px 1px 0px #999,
2px 2px 0px #999,
3px 3px 0px #999,
4px 4px 0px #999,
5px 5px 0px #999,
6px 6px 0px #999;
}
you can use pseudo element for as shadow
div {
background: black;
height: 100px;
width: 100px;
position: relative;
}
div:after,
div:before {
content: '';
background: grey;
position: absolute;
}
div:after {
width: 100%;
height: 20px;
left: 10px;
bottom: 0;
transform: translatey(100%) skewx(45deg);
}
div:before {
width: 20px;
height: 100%;
right: 0;
transform: translatex(100%) skewy(45deg);
top: 10px;
}
<div></div>
Here is a real 3D shadow using perspective and pseudo-element :before.
body {
background: lightblue;
}
.foo {
position: relative;
display: inline-block;
-webkit-perspective: 1000px;
-moz-perspective: 1000px;
persepctive: 1000px;
margin: 20px;
margin-top: 50px;
}
.foo .box {
transform: rotateY(-40deg);
height: 350px;
width: 250px;
background-color: black;
}
.foo:before {
content: "";
top: -15px;
position: absolute;
width: 50px;
height: 375px;
background-color: grey;
transform: translateX(215px) translateY(2.7px) rotateY(55deg)
}
<div class="foo">
<div class="box"></div>
</div>
You can stack the horizontal/vertical offsets of several box-shadows, each slightly bigger than the previous one. The more shadows you add, the more pronounced the effect. Here is a fiddle example.
div {
background: black;
height: 100px;
width: 100px;
box-shadow: 0 01px gray,
01px 0 gray,
01px 02px gray,
02px 01px gray,
02px 03px gray,
03px 02px gray,
03px 04px gray,
04px 03px gray,
04px 05px gray,
05px 04px gray,
05px 06px gray,
06px 05px gray;
}
I had some problems with these two options, so I adapted some diagonal gradients from Lea Verou's excellent book CSS Secrets. I thought about creating a gradient inside a right and bottom border via border-image, but that property does not allow edge targeting, à la border-right-image, etc.
So, I settled on using a pseudo element with two truncated corners, which seems to work pretty well. You have to be careful to adjust the width of the gradient to be 1.414 the size of half the padding, since this would be the diagonal of a square (square root of two). Also, since that's a pseudo element, be careful of the right placement. Interested to hear what you folks think.
div {
background: #bbb;
padding: 1em 1.2em;
width: 50%;
margin: 0 auto;
color: #111;
font: 150%/1.2 Georgia, Palatino, Times, serif;
position: relative;
}
div:after {
content:" ";
position:absolute;
top:0;
left: 0;
width:100%;
height:100%;
padding: 1.42em; /* (square root of gradient position) */
background: #000; /* Fallback if not supported */
background: linear-gradient(-135deg, transparent 2em, #000 0) top right,
linear-gradient(#000, #000) padding-box bottom right,
linear-gradient(45deg, transparent 2em, #000 0) bottom left;
/*I have avoided adding -webkit-, -moz and -0 prefixs for linear-gradient. You may put them in later to be extra safe*/
background-size: 50% 50%; /* There is no reason to paint the upper left quadrant, so I didn't. */
background-repeat: no-repeat;
-webkit-box-sizing: content-box; -moz-box-sizing: content-box; box-sizing: content-box;
/* Many people use border-box as default these days. Unfortunately, the box cannot be sized using border-box settings with the combination of padding in ems and percentages. So this is reset to content-box, just in case. */
z-index: -1; /* To keep the shadow behind the div*/
<div>This is a short sentence to demonstrate that our little div is responsive.</div>
Here's a little implementation, inspired by #Vitorino fernandes, in stylus...
offset = 10
border = 3
.offsetbox
margin offset
padding offset
text-align center
box-shadow inset 0 0 0 unit(border,px) black
background white
display inline-block
position relative
&:after,
&:before
content ''
background black
position absolute
&:after
width 100%
height offset
transform translatey(100%) skewx(-45deg)
right (offset/2)
bottom 0
&:before
height 100%
width offset
transform: translatex(-100%) skewy(-45deg)
left 0
top (offset/2)
I added some clip paths to #Vittorino fernandes code, to avoid white space between pseudos and make it sharper.
I added some 1px adjustments to avoid bad svg rendering problems.
You can use the variable called shadow-dimension to set the shadow width and height.
I Put it on a codePen:
https://codepen.io/silviamalavasi/pen/XWqeWEq
:root {
--shadow-dimension: 20px;
--blue: #0039a6;
}
.box-container {
position: relative;
}
.box-container>div {
border: 2px solid var(--blue);
}
.box-container>div:after, .box-container>div:before {
content: '';
background-color: var(--blue);
position: absolute;
}
.box-container>div:before {
width: calc(var(--shadow-dimension) + 1px);
height: calc(100% + 100px + 1px);
left: calc(var(--shadow-dimension) * -1);
transform: skewy(-45deg);
top: calc(0.5*var(--shadow-dimension));
clip-path: polygon(0% 0%, 100% 0%, 100% calc(100% - 100px - 2px + var(--shadow-dimension)), 0% calc(100% - 100px - 2px));
}
.box-container>div:after {
width: calc(100% + 100px);
height: calc(var(--shadow-dimension) + 1px);
left: calc(-0.5*var(--shadow-dimension) - 100px);
bottom: 1px;
transform: translateY(100%) skewx(-45deg);
clip-path: polygon(100px 0%, 100% 0%, 100% 100%, calc(100px + 2px) 100%);
}
I'm not sure what is specific name for this shape but can I just called it "half Parallelogram" ? I want make this shape purely using CSS/CSS3. Any help? or tutorial?
You can do it using pseudo-elements like below. The approach is to cut out a triangle shape from the left-bottom and top-right of the box. This method can be used with either a solid color an image inside the shape as long as the body background is a solid color. When the body background is a non-solid color this approach will not work because the border hack needs a solid color background.
The advantage of this method is that it can support cuts of different angles at each side (like in the question where the hypotenuse of the triangular cut on either side are not parallel to each other).
div {
background: red;
width: 200px;
height: 100px;
position: relative;
}
div:before {
position: absolute;
height: 0;
width: 0;
content: ' ';
border: 20px solid white;
border-color: transparent transparent white white;
border-width: 20px 0px 0px 15px;
left: 0;
top: 80px;
}
div:after {
position: absolute;
height: 0;
width: 0;
content: ' ';
border: 20px solid white;
border-color: white white transparent transparent;
left: 170px;
top: 0px;
}
.with-img {
background: url(http://lorempixel.com/100/100);
}
<div></div>
<br>
<div class="with-img"></div>
Sample 2: You can also achieve a similar effect using gradients. Just 1 gradient is enough to produce a cut of similar angle on both sides. If different angles are required then two gradients should be used. However the multiple gradient approach mentioned here will not work when the body background is a non-solid color.
div {
width: 200px;
height: 100px;
position: relative;
}
.with-single-gradient {
background: linear-gradient(45deg, transparent 5%, yellowgreen 5%, yellowgreen 90%, transparent 90.5%);
}
.with-single-gradient.image {
background: linear-gradient(45deg, white 5%, transparent 5%, transparent 90%, white 90.5%), url(http://lorempixel.com/100/100);
}
.with-multiple-gradient.image {
background: linear-gradient(45deg, transparent 0%, transparent 90%, white 90%), linear-gradient(60deg, white 10%, transparent 5%, transparent 100%), url(http://lorempixel.com/100/100);
}
<div class='with-single-gradient'></div>
<br>
<div class='with-single-gradient image'></div>
<br>
<div class='with-multiple-gradient image'></div>
Sample 3: This can also be created using SVG and is the best method yet. All that it requires is just a single path element which creates the required shape.
<svg viewBox='0 0 100 60' width='200px' height='120px'>
<path d='M0,0 80,0 100,16 100,60 10,60 0,54z' fill='yellowgreen' />
</svg>
Tested on Chrome v24, Firefox v19, Safari v5.1.7 (on Windows) and IE v10. They are older versions but should work in the latest versions also.
Note: IE versions less than 10 do not support gradients as mentioned in this SO thread.
there's no thing as straight radius, but here you have some tutorials. For weird shapes, you need to use a combination of shape and negative space, basically using figures with the same color of the background . The good news is you could use "transparent" as color, so you can "fake" this figures in an easy way. See tutorials Shapes of CSS or yuo can use a generator like CSS Shape Generator or CSS Shape Generator 2 but they will highly depend on your needs. Personally, I'd use a BG image and be a happy camper
to make this shape you have to use pseudo class.
and i hope it will help you
div { display: inline-block; margin: 20px; float: left; }
shape {
width: 208px;
height: 130px;
background: red;
position: relative; }
shape:before {
content: "";
position: absolute;
top: 0;
left: 0;
border-bottom: 29px solid red;
border-right: 29px solid #fff;
width: 179px;
height: 0; }
shape:after {
content: "";
position: absolute;
bottom: 0;
left: 0;
border-top: 29px solid red;
border-left: 29px solid #fff;
width: 42px;
height: 0; }
demo
2 gradients and background-size can be used too :
div {
width: 1440px;
height: 590px;
background:
linear-gradient(45deg, transparent 80px, #FF0000 80px) left no-repeat,
linear-gradient(-135deg, transparent 160px, #FF0000 160px) top right no-repeat;
background-size: 50% 100%;
}
<div>
</div>
1 gradients and calc() can be used too :
div {
width: 1440px;
height: 590px;
background:
linear-gradient(45deg, transparent 80px, #FF0000 80px, #FF0000 calc( 100% - 160px), transparent calc( 100% - 160px) );
}
<div>
</div>
Related to duplicate question https://stackoverflow.com/questions/36932294/how-can-i-create-the-object-in-picture-below-using-css-border-radius :
div {
width:980px;
height:460px;
background:linear-gradient(140deg,transparent 200px, #FFCB05 200px) left no-repeat,
linear-gradient(-40deg,transparent 80px, #FFCB05 80px) top right no-repeat;
background-size:50% 100% ;
}
<div>
div shape
</div>
image
<img src="http://i.stack.imgur.com/M48zP.png" />
For the second shape use this:
border-bottom-left-radius:50px;
border-top-right-radius:50px;
Check JSFiddle Demo
Edit:
Question is edited and second shape has been removed.
You can add an element with overflow: hidden;
skew transform the parent by desired angle. Unskew the pseudoelement by the negative of that angle.
Using this approach, you can also add images to background.
div {
height: 100px;
width: 220px;
overflow: hidden;
position: relative;
-webkit-transform: skewX(45deg);
-moz-transform: skewX(45deg);
transform: skewX(45deg);
}
div:before {
content: '';
position: absolute;
left: 10px;
height: 100px;
width: 200px;
background: red;
-webkit-transform: skewX(-45deg);
-moz-transform: skewX(-45deg);
transform: skewX(-45deg);
}
<div></div>
FIDDLE
FIDDLE (with image)
There're plenty of different CSS shapes over at CSS Tricks - Shapes of CSS and I'm particularly puzzled with a triangle:
#triangle-up {
width: 0;
height: 0;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 100px solid red;
}
<div id="triangle-up"></div>
How and why does it work?
CSS Triangles: A Tragedy in Five Acts
As alex said, borders of equal width butt up against each other at 45 degree angles:
When you have no top border, it looks like this:
Then you give it a width of 0...
...and a height of 0...
...and finally, you make the two side borders transparent:
That results in a triangle.
The borders use an angled edge where they intersect (45° angle with equal width borders, but changing the border widths can skew the angle).
div {
width: 60px;
border-width: 30px;
border-color: red blue green yellow;
border-style: solid;
}
<div></div>
Have a look to the jsFiddle.
By hiding certain borders, you can get the triangle effect (as you can see above by making the different portions different colours). transparent is often used as an edge colour to achieve the triangle shape.
Start with a basic square and borders. Each border will be given a different color so we can tell them apart:
.triangle {
border-color: yellow blue red green;
border-style: solid;
border-width: 200px 200px 200px 200px;
height: 0px;
width: 0px;
}
<div class="triangle"></div>
which gives you this:
But there's no need for the top border, so set its width to 0px. Now our border-bottom of 200px will make our triangle 200px tall.
.triangle {
border-color: yellow blue red green;
border-style: solid;
border-width: 0px 200px 200px 200px;
height: 0px;
width: 0px;
}
<div class="triangle"></div>
and we will get this:
Then to hide the two side triangles, set the border-color to transparent. Since the top-border has been effectively deleted, we can set the border-top-color to transparent as well.
.triangle {
border-color: transparent transparent red transparent;
border-style: solid;
border-width: 0px 200px 200px 200px;
height: 0px;
width: 0px;
}
<div class="triangle"></div>
finally we get this:
Different approach:
CSS3 triangles with transform rotate
Triangular shape is pretty easy to make using this technique. For people who prefer to see an animation explaining how this technique works here it is :
Link to the ANIMATION : How to make a CSS3 triangle.
And DEMO : CSS3 triangles made with transform rotate.
Otherwise, here is detailed explanation in 4 acts (this is not a tragedy) of how to make an isosceles right-angled triangle with one element.
Note 1 : for non isosceles triangles and fancy stuff, you can see step 4.
Note 2 : in the following snippets, the vendor prefixes aren't included. they are included in the codepen demos.
Note 3 : the HTML for the following explanation is always : <div class="tr"></div>
STEP 1 : Make a div
Easy, just make sure that width = 1.41 x height. You may use any techinque (see here) including the use of percentages and padding-bottom to maintain the aspect ratio and make a responsive triangle. In the following image, the div has a golden yellow border.
In that div, insert a pseudo element and give it 100% width and height of parent. The pseudo element has a blue background in the following image.
At this point, we have this CSS :
.tr {
width: 30%;
padding-bottom: 21.27%; /* = width / 1.41 */
position: relative;
}
.tr: before {
content: '';
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
background: #0079C6;
}
STEP 2 : Let's rotate
First, most important : define a transform origin. The default origin is in the center of the pseudo element and we need it at the bottom left. By adding this CSS to the pseudo element :
transform-origin:0 100%; or transform-origin: left bottom;
Now we can rotate the pseudo element 45 degrees clockwise with transform : rotate(45deg);
At this point, we have this CSS :
.tr {
width: 30%;
padding-bottom: 21.27%; /* = width / 1.41 */
position: relative;
}
.tr:before {
content: '';
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
background: #0079C6;
transform-origin: 0 100%;
transform: rotate(45deg);
}
STEP 3 : hide it
To hide the unwanted parts of the pseudo element (everything that overflows the div with the yellow border) you just need to set overflow:hidden; on the container. after removing the yellow border, you get... a TRIANGLE! :
DEMO
CSS :
.tr {
width: 30%;
padding-bottom: 21.27%; /* = width / 1.41 */
position: relative;
overflow: hidden;
}
.tr:before {
content: '';
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
background-color: #0079C6;
transform-origin: 0 100%;
transform: rotate(45deg);
}
STEP 4 : go further...
As shown in the demo, you can customize the triangles :
Make them thinner or flatter by playing with skewX().
Make them point left, right or any other direction by playing with the transform origin and rotation direction.
Make some reflexion with 3D transform property.
Give the triangle borders
Put an image inside the triangle
Much more... Unleash the powers of CSS3!
Why use this technique?
Triangle can easily be responsive.
You can make a triangle with border.
You can maintain the boundaries of the triangle. This means that you can trigger the hover state or click event only when the cursor is inside the triangle. This can become very handy in some situations like this one where each triangle can't overlay its neighbours so each triangle has its own hover state.
You can make some fancy effects like reflections.
It will help you understand 2d and 3d transform properties.
Why not use this technique?
The main drawback is the browser compatibility, the 2d transform properties are supported by IE9+ and therefore you can't use this technique if you plan on supporting IE8. See CanIuse for more info. For some fancy effects using 3d transforms like the reflection browser support is IE10+ (see canIuse for more info).
You don't need anything responsive and a plain triangle is fine for you then you should go for the border technique explained here : better browser compatibility and easier to understand thanks to the amazing posts here.
Here is an animation in JSFiddle I created for demonstration.
Also see snippet below.
This is an Animated GIF made from a Screencast
transforms = [
{'border-left-width' :'30', 'margin-left': '70'},
{'border-bottom-width' :'80'},
{'border-right-width' :'30'},
{'border-top-width' :'0', 'margin-top': '70'},
{'width' :'0'},
{'height' :'0', 'margin-top': '120'},
{'borderLeftColor' :'transparent'},
{'borderRightColor' :'transparent'}
];
$('#a').click(function() {$('.border').trigger("click");});
(function($) {
var duration = 1000
$('.border').click(function() {
for ( var i=0; i < transforms.length; i++ ) {
$(this)
.animate(transforms[i], duration)
}
}).end()
}(jQuery))
.border {
margin: 20px 50px;
width: 50px;
height: 50px;
border-width: 50px;
border-style: solid;
border-top-color: green;
border-right-color: yellow;
border-bottom-color: red;
border-left-color: blue;
cursor: pointer
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script src="https://code.jquery.com/color/jquery.color-2.1.2.min.js"></script>
Click it!<br>
<div class="border"></div>
Random version
/**
* Randomize array element order in-place.
* Using Durstenfeld shuffle algorithm.
*/
function shuffleArray(array) {
for (var i = array.length - 1; i > 0; i--) {
var j = Math.floor(Math.random() * (i + 1));
var temp = array[i];
array[i] = array[j];
array[j] = temp;
}
return array;
}
transforms = [
{'border-left-width' :'30', 'margin-left': '70'},
{'border-bottom-width' :'80'},
{'border-right-width' :'30'},
{'border-top-width' :'0', 'margin-top': '70'},
{'width' :'0'},
{'height' :'0'},
{'borderLeftColor' :'transparent'},
{'borderRightColor' :'transparent'}
];
transforms = shuffleArray(transforms)
$('#a').click(function() {$('.border').trigger("click");});
(function($) {
var duration = 1000
$('.border').click(function() {
for ( var i=0; i < transforms.length; i++ ) {
$(this)
.animate(transforms[i], duration)
}
}).end()
}(jQuery))
.border {
margin: 50px;
width: 50px;
height: 50px;
border-width: 50px;
border-style: solid;
border-top-color: green;
border-right-color: yellow;
border-bottom-color: red;
border-left-color: blue;
cursor: pointer
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script src="https://code.jquery.com/color/jquery.color-2.1.2.min.js"></script>
Click it!<br>
<div class="border"></div>
All at once version
$('#a').click(function() {$('.border').trigger("click");});
(function($) {
var duration = 1000
$('.border').click(function() {
$(this)
.animate({'border-top-width': 0 ,
'border-left-width': 30 ,
'border-right-width': 30 ,
'border-bottom-width': 80 ,
'width': 0 ,
'height': 0 ,
'margin-left': 100,
'margin-top': 150,
'borderTopColor': 'transparent',
'borderRightColor': 'transparent',
'borderLeftColor': 'transparent'}, duration)
}).end()
}(jQuery))
.border {
margin: 50px;
width: 50px;
height: 50px;
border-width: 50px;
border-style: solid;
border-top-color: green;
border-right-color: yellow;
border-bottom-color: red;
border-left-color: blue;
cursor: pointer
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script src="https://code.jquery.com/color/jquery.color-2.1.2.min.js"></script>
Click it!<br>
<div class="border"></div>
Lets say we have the following div:
<div id="triangle" />
Now Edit the CSS step-by-step, so you will get clear idea what is happening around
STEP 1:
JSfiddle Link:
#triangle {
background: purple;
width :150px;
height:150PX;
border-left: 50px solid black ;
border-right: 50px solid black;
border-bottom: 50px solid black;
border-top: 50px solid black;
}
This is a simple div. With a very simple CSS. So a layman can understand. Div has dimensions 150 x 150 pixels with the border 50 pixels. The image is attached:
STEP 2: JSfiddle Link:
#triangle {
background: purple;
width :150px;
height:150PX;
border-left: 50px solid yellow ;
border-right: 50px solid green;
border-bottom: 50px solid red;
border-top: 50px solid blue;
}
Now I just changed the border-color of all 4 sides. The image is attached.
STEP:3 JSfiddle Link:
#triangle {
background: purple;
width :0;
height:0;
border-left: 50px solid yellow ;
border-right: 50px solid green;
border-bottom: 50px solid red;
border-top: 50px solid blue;
}
Now I just changed the height & width of div from 150 pixels to zero. The image is attached
STEP 4: JSfiddle:
#triangle {
background: purple;
width :0px;
height:0px;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 50px solid red;
border-top: 50px solid transparent;
}
Now I have made all the borders transparent apart from the bottom border. The image is attached below.
STEP 5: JSfiddle Link:
#triangle {
background: white;
width :0px;
height:0px;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 50px solid red;
border-top: 50px solid transparent;
}
Now I just changed the background color to white. The image is attached.
Hence we got the triangle we needed.
And now something completely different...
Instead of using css tricks don't forget about solutions as simple as html entities:
▲
Result:
▲
See: What are the HTML entities for up and down triangles?
Consider the below triangle
.triangle {
border-bottom:15px solid #000;
border-left:10px solid transparent;
border-right:10px solid transparent;
width:0;
height:0;
}
This is what we are given:
Why it came out in this shape? The below diagram explains the dimensions, note that 15px was used for the bottom border and 10px was used for left and right.
It's pretty easy to make a right-angle triangle also by removing the right border.
Taking it one step further, using css based on this I added arrows to my back and next buttons (yes I know its not 100% cross-browser, but slick none the less).
.triangle {
width: 0;
height: 0;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 100px solid red;
margin:20px auto;
}
.triangle-down {
border-bottom:none;
border-top: 100px solid red;
}
.triangle-left {
border-left:none;
border-right: 100px solid red;
border-bottom: 50px solid transparent;
border-top: 50px solid transparent;
}
.triangle-right {
border-right:none;
border-left: 100px solid red;
border-bottom: 50px solid transparent;
border-top: 50px solid transparent;
}
.triangle-after:after {
width: 0;
height: 0;
border-left: 5px solid transparent;
border-right: 5px solid transparent;
border-bottom: 5px solid red;
margin:0 5px;
content:"";
display:inline-block;
}
.triangle-after-right:after {
border-right:none;
border-left: 5px solid blue;
border-bottom: 5px solid transparent;
border-top: 5px solid transparent;
}
.triangle-before:before {
width: 0;
height: 0;
border-left: 5px solid transparent;
border-right: 5px solid transparent;
border-bottom: 5px solid blue;
margin:0 5px;
content:"";
display:inline-block;
}
.triangle-before-left:before {
border-left:none;
border-right: 5px solid blue;
border-bottom: 5px solid transparent;
border-top: 5px solid transparent;
}
<div class="triangle"></div>
<div class="triangle triangle-down"></div>
<div class="triangle triangle-left"></div>
<div class="triangle triangle-right"></div>
<a class="triangle-before triangle-before-left" href="#">Back</a>
<a class="triangle-after triangle-after-right" href="#">Next</a>
CSS clip-path
This is something I feel this question has missed; clip-path
clip-path in a nutshell
Clipping, with the clip-path property, is akin to cutting a shape (like a circle or a pentagon) from a rectangular piece of paper. The property belongs to the “CSS Masking Module Level 1” specification. The spec states, “CSS masking provides two means for partially or fully hiding portions of visual elements: masking and clipping”.
Extract from Smashing Magazine
clip-path will use the element itself rather than its borders to cut the shape you specify in its parameters. It uses a super simple percentage based co-ordinate system which makes editing it very easy and means you can pick it up and create weird and wonderful shapes in a matter of minutes.
Triangle Shape Example
div {
-webkit-clip-path: polygon(50% 0%, 0% 100%, 100% 100%);
clip-path: polygon(50% 0%, 0% 100%, 100% 100%);
background: red;
width: 100px;
height: 100px;
}
<div></div>
Downside
It does have a major downside at the moment, one being it's major lack of support, only really being covered within -webkit- browsers and having no support on IE and only very partial in FireFox.
Resources
Here are some useful resources and material to help better understand clip-path and also start creating your own.
Clippy - A clip-path generator
The W3C Candidate Recommendation File
MDN clip-path documentation
clip-path Browser Support
Different approach. With linear gradient (for IE, only IE 10+).
You can use any angle:
.triangle {
margin: 50px auto;
width: 100px;
height: 100px;
/* linear gradient */
background: -moz-linear-gradient(-45deg, rgba(255,0,0,0) 0%, rgba(255,0,0,0) 50%, rgba(255,0,0,1) 50%, rgba(255,0,0,1) 100%);
/* FF3.6+ */
background: -webkit-gradient(linear, left top, right bottom, color-stop(0%,rgba(255,0,0,0)), color-stop(50%,rgba(255,0,0,0)), color-stop(50%,rgba(255,0,0,1)), color-stop(100%,rgba(255,0,0,1)));
/* Chrome,Safari4+ */
background: -webkit-linear-gradient(-45deg, rgba(255,0,0,0) 0%,rgba(255,0,0,0) 50%,rgba(255,0,0,1) 50%,rgba(255,0,0,1) 100%);
/* Chrome10+,Safari5.1+ */
background: -o-linear-gradient(-45deg, rgba(255,0,0,0) 0%,rgba(255,0,0,0) 50%,rgba(255,0,0,1) 50%,rgba(255,0,0,1) 100%);
/* Opera 11.10+ */
background: -ms-linear-gradient(-45deg, rgba(255,0,0,0) 0%,rgba(255,0,0,0) 50%,rgba(255,0,0,1) 50%,rgba(255,0,0,1) 100%);
/* IE10+ */
background: linear-gradient(135deg, rgba(255,0,0,0) 0%,rgba(255,0,0,0) 50%,rgba(255,0,0,1) 50%,rgba(255,0,0,1) 100%);
/* W3C */;
}
<div class="triangle"></div>
Here is jsfiddle
OK, this triangle will get created because of the way that borders of the elements work together in HTML and CSS...
As we usually use 1 or 2px borders, we never notice that borders make a 45° angles to each others with the same width and if the width changes, the angle degree get changed as well, run the CSS code I created below:
.triangle {
width: 100px;
height: 100px;
border-left: 50px solid black;
border-right: 50px solid black;
border-bottom: 100px solid red;
}
<div class="triangle">
</div>
Then in the next step, we don't have any width or height, something like this:
.triangle {
width: 0;
height: 0;
border-left: 50px solid black;
border-right: 50px solid black;
border-bottom: 100px solid red;
}
<div class="triangle">
</div>
And now we make the left and right borders invisible to make our desirable triangle as below:
.triangle {
width: 0;
height: 0;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 100px solid red;
}
<div class="triangle"></div>
If you not willing to run the snippet to see the steps, I've created an image sequence to have a look at all steps in one image:
This is an old question, but I think will worth it to share how to create an arrow using this triangle technique.
Step 1:
Lets create 2 triangles, for the second one we will use the :after pseudo class and position it just below the other:
.arrow{
width: 0;
height: 0;
border-radius: 50px;
display: inline-block;
position: relative;
}
.arrow:after{
content: "";
width: 0;
height: 0;
position: absolute;
}
.arrow-up{
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 50px solid #333;
}
.arrow-up:after{
top: 5px;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 50px solid #ccc;
right: -50px;
}
<div class="arrow arrow-up"> </div>
Step 2
Now we just have to set the predominant border color of the second triangle to the same color of the background:
.arrow{
width: 0;
height: 0;
border-radius: 50px;
display: inline-block;
position: relative;
}
.arrow:after{
content: "";
width: 0;
height: 0;
position: absolute;
}
.arrow-up{
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 50px solid #333;
}
.arrow-up:after{
top: 5px;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 50px solid #fff;
right: -50px;
}
<div class="arrow arrow-up"> </div>
Fiddle with all the arrows:
http://jsfiddle.net/tomsarduy/r0zksgeu/
If you want to apply border to the triangle read this: Create a triangle with CSS?
Almost all the answers focus on the triangle built using border so I am going to elaborate the linear-gradient method (as started in the answer of #lima_fil).
Using a degree value like 45° will force us to respect a specific ratio of height/width in order to obtain the triangle we want and this won't be responsive:
.tri {
width:100px;
height:100px;
background:linear-gradient(45deg, transparent 49.5%,red 50%);
/*To illustrate*/
border:1px solid;
}
Good one
<div class="tri"></div>
bad one
<div class="tri" style="width:150px"></div>
bad one
<div class="tri" style="height:30px"></div>
Instead of doing this we should consider predefined values of direction like to bottom, to top, etc. In this case we can obtain any kind of triangle shape while keeping it responsive.
1) Rectangle triangle
To obtain such triangle we need one linear-gradient and a diagonal direction like to bottom right, to top left, to bottom left, etc
.tri-1,.tri-2 {
display:inline-block;
width:100px;
height:100px;
background:linear-gradient(to bottom left, transparent 49.5%,red 50%);
border:1px solid;
animation:change 2s linear infinite alternate;
}
.tri-2 {
background:linear-gradient(to top right, transparent 49.5%,red 50%);
border:none;
}
#keyframes change {
from {
width:100px;
height:100px;
}
to {
height:50px;
width:180px;
}
}
<div class="tri-1"></div>
<div class="tri-2"></div>
2) isosceles triangle
For this one we will need 2 linear-gradient like above and each one will take half the width (or the height). It's like we create a mirror image of the first triangle.
.tri {
display:inline-block;
width:100px;
height:100px;
background-image:
linear-gradient(to bottom right, transparent 49.5%,red 50%),
linear-gradient(to bottom left, transparent 49.5%,red 50%);
background-size:50.3% 100%; /* I use a value slightly bigger than 50% to avoid having a small gap between both gradient*/
background-position:left,right;
background-repeat:no-repeat;
animation:change 2s linear infinite alternate;
}
#keyframes change {
from {
width:100px;
height:100px;
}
to {
height:50px;
width:180px;
}
}
<div class="tri"></div>
3) equilateral triangle
This one is a bit tricky to handle as we need to keep a relation between the height and width of the gradient. We will have the same triangle as above but we will make the calculation more complex in order to transform the isosceles triangle to an equilateral one.
To make it easy, we will consider that the width of our div is known and the height is big enough to be able to draw our triangle inside (height >= width).
We have our two gradient g1 and g2, the blue line is the width of the div w and each gradient will have 50% of it (w/2) and each side of the triangle sould be equal to w. The green line is the height of both gradient hg and we can easily obtain the formula below:
(w/2)² + hg² = w² ---> hg = (sqrt(3)/2) * w ---> hg = 0.866 * w
We can rely on calc() in order to do our calculation and to obtain the needed result:
.tri {
--w:100px;
width:var(--w);
height:100px;
display:inline-block;
background-image:
linear-gradient(to bottom right, transparent 49.5%,red 50%),
linear-gradient(to bottom left, transparent 49.5%,red 50%);
background-size:calc(var(--w)/2 + 0.5px) calc(0.866 * var(--w));
background-position:
left bottom,right bottom;
background-repeat:no-repeat;
}
<div class="tri"></div>
<div class="tri" style="--w:80px"></div>
<div class="tri" style="--w:50px"></div>
Another way is to control the height of div and keep the syntax of gradient easy:
.tri {
--w:100px;
width:var(--w);
height:calc(0.866 * var(--w));
display:inline-block;
background:
linear-gradient(to bottom right, transparent 49.8%,red 50%) left,
linear-gradient(to bottom left, transparent 49.8%,red 50%) right;
background-size:50.2% 100%;
background-repeat:no-repeat;
}
<div class="tri"></div>
<div class="tri" style="--w:80px"></div>
<div class="tri" style="--w:50px"></div>
4) Random triangle
To obtain a random triangle, it's easy as we simply need to remove the condition of 50% of each one BUT we should keep two condition (both should have the same height and the sum of both width should be 100%).
.tri-1 {
width:100px;
height:100px;
display:inline-block;
background-image:
linear-gradient(to bottom right, transparent 50%,red 0),
linear-gradient(to bottom left, transparent 50%,red 0);
background-size:20% 60%,80% 60%;
background-position:
left bottom,right bottom;
background-repeat:no-repeat;
}
<div class="tri-1"></div>
But what if we want to define a value for each side? We simply need to do calculation again!
Let's define hg1 and hg2 as the height of our gradient (both are equal to the red line) then wg1 and wg2 as the width of our gradient (wg1 + wg2 = a). I will not going to detail the calculation but at then end we will have:
wg2 = (a²+c²-b²)/(2a)
wg1 = a - wg2
hg1 = hg2 = sqrt(b² - wg1²) = sqrt(c² - wg2²)
Now we have reached the limit of CSS as even with calc() we won't be able to implement this so we simply need to gather the final result manually and use them as fixed size:
.tri {
--wg1: 20px;
--wg2: 60px;
--hg:30px;
width:calc(var(--wg1) + var(--wg2));
height:100px;
display:inline-block;
background-image:
linear-gradient(to bottom right, transparent 49.5%,red 50%),
linear-gradient(to bottom left, transparent 49.5%,red 50%);
background-size:var(--wg1) var(--hg),var(--wg2) var(--hg);
background-position:
left bottom,right bottom;
background-repeat:no-repeat;
}
<div class="tri" ></div>
<div class="tri" style="--wg1:80px;--wg2:60px;--hg:100px;" ></div>
Bonus
We should not forget that we can also apply rotation and/or skew and we have more option to obtain more triangle:
.tri {
--wg1: 20px;
--wg2: 60px;
--hg:30px;
width:calc(var(--wg1) + var(--wg2) - 0.5px);
height:100px;
display:inline-block;
background-image:
linear-gradient(to bottom right, transparent 49%,red 50%),
linear-gradient(to bottom left, transparent 49%,red 50%);
background-size:var(--wg1) var(--hg),var(--wg2) var(--hg);
background-position:
left bottom,right bottom;
background-repeat:no-repeat;
}
<div class="tri" ></div>
<div class="tri" style="transform:skewY(25deg)"></div>
<div class="tri" style="--wg1:80px;--wg2:60px;--hg:100px;" ></div>
<div class="tri" style="--wg1:80px;--wg2:60px;--hg:100px;transform:rotate(20deg)" ></div>
And of course we should keep in mind the SVG solution which can be more suitable in some situation:
svg {
width:100px;
height:100px;
}
polygon {
fill:red;
}
<svg viewBox="0 0 100 100"><polygon points="0,100 0,0 100,100" /></svg>
<svg viewBox="0 0 100 100"><polygon points="0,100 50,0 100,100" /></svg>
<svg viewBox="0 0 100 100"><polygon points="0,100 50,23 100,100" /></svg>
<svg viewBox="0 0 100 100"><polygon points="20,60 50,43 80,100" /></svg>
SASS (SCSS) triangle mixin
I wrote this to make it easier (and DRY) to automatically generate a CSS triangle:
// Triangle helper mixin (by Yair Even-Or)
// #param {Direction} $direction - either `top`, `right`, `bottom` or `left`
// #param {Color} $color [currentcolor] - Triangle color
// #param {Length} $size [1em] - Triangle size
#mixin triangle($direction, $color: currentcolor, $size: 1em) {
$size: $size/2;
$transparent: rgba($color, 0);
$opposite: (top:bottom, right:left, left:right, bottom:top);
content: '';
display: inline-block;
width: 0;
height: 0;
border: $size solid $transparent;
border-#{map-get($opposite, $direction)}-color: $color;
margin-#{$direction}: -$size;
}
use-case example:
span {
#include triangle(bottom, red, 10px);
}
Playground page
Important note: if the triangle seems pixelated in some browsers, try one of the methods described here.
If you want to play around with border-size, width and height and see how those can create different shapes, try this:
const sizes = [32, 32, 32, 32];
const triangle = document.getElementById('triangle');
function update({ target }) {
let index = null;
if (target) {
index = parseInt(target.id);
if (!isNaN(index)) {
sizes[index] = target.value;
}
}
window.requestAnimationFrame(() => {
triangle.style.borderWidth = sizes.map(size => `${ size }px`).join(' ');
if (isNaN(index)) {
triangle.style[target.id] = `${ target.value }px`;
}
});
}
document.querySelectorAll('input').forEach(input => {
input.oninput = update;
});
update({});
body {
margin: 0;
min-height: 100vh;
display: flex;
justify-content: center;
align-items: center;
overflow: hidden;
}
#triangle {
border-style: solid;
border-color: yellow magenta blue black;
background: cyan;
height: 0px;
width: 0px;
}
#controls {
position: fixed;
bottom: 0;
left: 0;
right: 0;
background: white;
display: flex;
box-shadow: 0 0 32px rgba(0, 0, 0, .125);
}
#controls > div {
position: relative;
width: 25%;
padding: 8px;
box-sizing: border-box;
display: flex;
}
input {
margin: 0;
width: 100%;
position: relative;
}
<div id="triangle" style="border-width: 32px 32px 32px 32px;"></div>
<div id="controls">
<div><input type="range" min="0" max="128" value="32" id="0" /></div>
<div><input type="range" min="0" max="128" value="32" id="1" /></div>
<div><input type="range" min="0" max="128" value="32" id="2" /></div>
<div><input type="range" min="0" max="128" value="32" id="3" /></div>
<div><input type="range" min="0" max="128" value="0" id="width" /></div>
<div><input type="range" min="0" max="128" value="0" id="height" /></div>
</div>
here is another fiddle:
.container:after {
position: absolute;
right: 0;
content: "";
margin-right:-50px;
margin-bottom: -8px;
border-width: 25px;
border-style: solid;
border-color: transparent transparent transparent #000;
width: 0;
height: 0;
z-index: 10;
-webkit-transition: visibility 50ms ease-in-out,opacity 50ms ease-in-out;
transition: visibility 50ms ease-in-out,opacity 50ms ease-in-out;
bottom: 21px;
}
.container {
float: left;
margin-top: 100px;
position: relative;
width: 150px;
height: 80px;
background-color: #000;
}
.containerRed {
float: left;
margin-top: 100px;
position: relative;
width: 100px;
height: 80px;
background-color: red;
}
https://jsfiddle.net/qdhvdb17/
Others have already explained this well. Let me give you an animation which will explain this quickly: http://codepen.io/chriscoyier/pen/lotjh
Here is some code for you to play with and learn the concepts.
HTML:
<html>
<body>
<div id="border-demo">
</div>
</body>
</html>
CSS:
/*border-width is border thickness*/
#border-demo {
background: gray;
border-color: yellow blue red green;/*top right bottom left*/
border-style: solid;
border-width: 25px 25px 25px 25px;/*top right bottom left*/
height: 50px;
width: 50px;
}
Play with this and see what happens. Set height and width to zero. Then remove top border and make left and right transparent, or just look at the code below to make a css triangle:
#border-demo {
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 100px solid blue;
}
I know this is an old one, but I'd like to add to this discussion that There are at least 5 different methods for creating a triangle using HTML & CSS alone.
Using borders
Using linear-gradient
Using conic-gradient
Using
transform and overflow
Using clip-path
I think that all have been covered here except for method 3, using the conic-gradient, so I will share it here:
.triangle{
width: 40px;
height: 40px;
background: conic-gradient(at 50% 50%,transparent 135deg,green 0,green 225deg, transparent 0);
}
<div class="triangle"></div>
use clip-path: polygon(50% 0%, 100% 100%, 0% 100%); for creating easy to Triangle
<div class="triangle"></div>
.triangle{width:200px; height:200px;background:#000;clip-path: polygon(50% 0%, 100% 100%, 0% 100%);}
After reading through the other answers here I see there are great explanations as to why the CSS triangle works the way it does. I would consider it to be somewhat of a trick, versus something that you could apply generically.
For something that's easier to read and maintain, I would recommend you define your geometry in SVG.
Then you can convert that SVG using data uri by adding the data:image/svg+xml, prefix. As a data uri, it can now be used as a background-image in a CSS. Because the SVG is in clear text, you can readily make updates to the geometry, stroke, and fill color.
div.tri {
width: 100px;
height: 100px;
display: inline-block;
background-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32"><path fill="red" d="M31.345 29H1.655L16.5 1.96z"/></svg>');
}
<div>
<div class="tri"></div>
<div class="tri"></div>
<div class="tri"></div>
</div>
Try This:-
.triangle {
border-color: transparent transparent red transparent;
border-style: solid;
border-width: 0px 200px 200px 200px;
height: 0px;
width: 0px;
}
<div class="triangle"></div>
clip-path has the best result for me - works great for divs/containers with and without fixed dimensions:
.triangleContainer{
position: relative;
width: 500px;
height: 500px;
}
.triangleContainer::before{
content: "";
position: absolute;
background:blue;
top: 0;
left: 0;
width: 100%;
height: 100%;
clip-path: polygon(50% 0, 0 100%, 100% 100%);
}