I have seen some web design lessons that always start with a css like this:
body,html {
display: block;
width: 100%;
height: 100%;
padding: 0;
margin: 0;
}
I'm trying to figure out what's the point of declaring attributes like width, height or display for body and html that are, if I'm not wrong, by default in browsers.
I thought it would be to prevent and undefined return or similar when accessing the css with js, but the result is the same when the attributes are defined in the css than when left to default:
console.log($("BODY").css('width')); // Always returns the width of the body
I also thought it could be to start the inheritance in cascade elements, but a div inside the body inherits the value just the same.
Anybody knows a solid reason for this approach? any browser / device issue I have missed? future compatibility? plain pedantry?
I'm kind of curious about it.
I found a good reason to define the html and body width and height to 100%. Say you want to vertically align a relative positioned div, you need to put it into an absolute positioned container:
html,
body {
margin: 0;
padding: 0;
}
#container {
position: absolute;
width: 100%;
height: 100%;
}
#main {
background: lightgrey;
position: relative;
top: 50%;
transform: translateY(-50%);
width: 100px;
height: 100px;
text-align: center;
margin-left: auto;
margin-right: auto;
}
<div id="container">
<div id="main">
<h1>MY DIV</h1>
</div>
</div>
But, setting the body width and height to 100% you get an absolute positioned container that covers the whole window:
html,
body {
margin: 0;
padding: 0;
width: 100%;
height: 100%;
}
#main {
background: lightgrey;
position: relative;
top: 50%;
transform: translateY(-50%);
width: 100px;
height: 100px;
text-align: center;
margin-left: auto;
margin-right: auto;
}
<div id="main">
<h1>MY DIV</h1>
</div>
You get the same result, but it saves you a div element.
Related
Here is the code. I want the DIV.fixed-nav (position:fixed) to completely fit its parent DIV.container of which width may change. Is there a pure CSS solution for this?
CSS:
body {
margin: 0;
padding: 0;
}
.container {
border: 1px solid #000000;
margin: 0 auto;
max-width: 600px;
min-width: 400px;
}
.fixed-nav {
background-color: red;
height: 20px;
position: fixed;
width: 100%;
top: 0;
z-index: 99;
}
.content {
background-color: green;
height: 100px;
margin-top: 20px;
}
HTML:
<div class="container">
<div class="fixed-nav">
</div>
<div class="content">
</div>
</div>
Please check the DEMO.
The problem with fixed is that it will always be relative to the browser window. So if you set 100% height on your fixed container it will be 100% of the browser window.
The only way I could think of to achieve this is to use jQuery. Or if you don't need the menu to be fixed and it could be absolute then height 100% will work.
I have a blog post that is 960 pixels wide.
I want parts of this blogpost to cover 100% of the viewport (from left: 0 to right: 0). It's fairly easy to do with absolute positioning but using this approach it's impossible to clear these 100%-wide elements.
HTML:
<div class="wrapper">
<h1>A header</h1>
<p>Some content.</p>
<div class="out">
<blockquote>Some blockquote.<br/> Another line.<br/>And another.</blockquote>
</div>
<p>Clears don't work here and this content is invisible :( </p>
<p>And this sucks :( </p>
<div class="out">
<blockquote>And different blockquote.<br/> Another line.<br/></blockquote>
</div>
<p>Also this is behind blockquote as well.</p>
</div>
CSS:
body {
position: relative;
}
.wrapper {
margin: 0 auto;
padding: 15px;
background: #eee;
width: 400px;
height: 1000px;
}
.out {
position: absolute;
right: 0;
left: 0;
padding: 15px;
background: #aaa;
width: 100%:
}
blockquote {
margin: 0 auto;
width: 400px;
}
Here's a demo:
http://jsfiddle.net/2rC2S/1/
Note: all blockquotes have different height so I can't set it for them. I don't want to use JavaScript (because it's fairly easy to get elements height, set this and boom, but who renders content with JS?!).
You may do this by using before and after pseudo selectors as follows
.out:before, .out:after {
content:"";
background: black;
position: absolute;
top: 0;
bottom: 0;
width: 9999px;
}
.out:before {
right: 100%;
}
.out:after {
left: 100%;
}
http://jsfiddle.net/kM3Gf/
you may find original article here http://css-tricks.com/examples/FullBrowserWidthBars/
still I am not sure about browser compatibility!
Maybe you can avoid setting the width for the wrapper and instead set it for each of the content elements?
An absolutely positioned element won't take up space in the document and thus won't push any content down.
See this DEMO
.wrapper h1, .wrapper p {
margin: 0 auto;
padding: 15px;
background: #eee;
width: 400px;
}
I need the div to be in the center of the page at all times whether user resizes webpage or not.
I have tried using:
margin: auto;
margin: 0 auto;
margin-left: auto; margin-right auto;
but neither of those three worked.
HTML:
<div id="grayinnerbackground">
</div>
CSS:
div#grayinnerbackground {
margin: auto;
width:1000px;
background-color: #D9D9D9;
height: 100%;
position: fixed;
z-index: -1;
}
Here is a fiddle for an example of what I'm talking about.
http://jsfiddle.net/ymvDJ/
Thanks.
If you do want the position to be fixed, add these rules and drop the usual margin trick:
left: 50%;
margin-left: -25px; // half the width of your element
See it here: http://jsfiddle.net/8DfnG/2/
You can use
position: fixed;
left: 50%;
width: 50px;
margin-left: -25px; /* width รท 2 */
Demo: http://jsfiddle.net/ymvDJ/3/
Use:
position: relative
If that still doesn't work you may need to add this as well:
display: block;
"position: fixed" means that no matter what it stays at a x and y coordinate.
You can try this
div#grayinnerbackground {
margin: auto;
position: absolute;
top: 0; left: 0; bottom: 0; right: 0;
width: 50px;
background-color: #D9D9D9;
height: 100%;
}
http://jsfiddle.net/g49Mb/
More about the working here: http://codepen.io/shshaw/full/gEiDt
This this HTML:
<div id="grayinnerbackground">
foo
</div>
CSS:
div#grayinnerbackground {
margin: auto;
width: 50px;
background-color: #ccc;
height: 100%;
}
I'm not entirely sure why it didn't work until I put text into the div, checking something now.
UPDATE
Sigh, ok, i'm tired. If the div is empty, and you have a height of 100%, it is going to be 100% the height of its parent, the <body> in this case. Since there is no other content, the <body> has a height of 0. Give the <div> an absolute height, and it will pop in:
div#grayinnerbackground {
margin: auto;
width: 50px;
background-color: #ccc;
height: 10px;
}
Remove position: fixed, change the width to 50px and make sure you have a 0 before auto in margin: auto.
Update:
To have the div be as high as the window, be sure to set the body and html to height: 100%; too:
body, html {
height: 100%:
}
Updated jsfiddle again
I'm trying to understand what appears to be unexpected behaviour to me:
I have an element with a max-height of 100% inside a container that also uses a max-height but, unexpectedly, the child overflows the parent:
.container {
background: blue;
padding: 10px;
max-height: 200px;
max-width: 200px;
}
img {
display: block;
max-height: 100%;
max-width: 100%;
}
<div class="container">
<img src="http://placekitten.com/400/500" />
</div>
This is fixed, however, if the parent is given an explicit height:
.container {
background: blue;
padding: 10px;
max-height: 200px;
max-width: 200px;
height: 200px;
}
img {
display: block;
max-height: 100%;
max-width: 100%;
}
<div class="container">
<img src="http://placekitten.com/400/500" />
</div>
Does anyone know why the child would not honour the max-height of its parent in the first example? Why is an explicit height required?
When you specify a percentage for max-height on a child, it is a percentage of the parent's actual height, not the parent's max-height, oddly enough. The same applies to max-width.
So, when you don't specify an explicit height on the parent, then there's no base height for the child's max-height to be calculated from, so max-height computes to none, allowing the child to be as tall as possible. The only other constraint acting on the child now is the max-width of its parent, and since the image itself is taller than it is wide, it overflows the container's height downwards, in order to maintain its aspect ratio while still being as large as possible overall.
When you do specify an explicit height for the parent, then the child knows it has to be at most 100% of that explicit height. That allows it to be constrained to the parent's height (while still maintaining its aspect ratio).
.container {
background: blue;
padding: 10px;
max-height: 200px;
max-width: 200px;
float: left;
margin-right: 20px;
}
.img1 {
display: block;
max-height: 100%;
max-width: 100%;
}
.img2 {
display: block;
max-height: inherit;
max-width: inherit;
}
<!-- example 1 -->
<div class="container">
<img class='img1' src="http://via.placeholder.com/350x450" />
</div>
<!-- example 2 -->
<div class="container">
<img class='img2' src="http://via.placeholder.com/350x450" />
</div>
I played around a little. On a larger image in firefox, I got a good result with using the inherit property value. Will this help you?
.container {
background: blue;
padding: 10px;
max-height: 100px;
max-width: 100px;
text-align:center;
}
img {
max-height: inherit;
max-width: inherit;
}
Instead of going with max-height: 100%/100%, an alternative approach of filling up all the space would be using position: absolute with top/bottom/left/right set to 0.
In other words, the HTML would look like the following:
<div class="flex-content">
<div class="scrollable-content-wrapper">
<div class="scrollable-content">
1, 2, 3
</div>
</div>
</div>
.flex-content {
flex-grow: 1;
position: relative;
width: 100%;
height: 100%;
}
.scrollable-content-wrapper {
position: absolute;
left: 0;
right: 0;
top: 0;
bottom: 0;
overflow: auto;
}
.scrollable-content {
/* Add styling here */
}
Try it below:
.flex-content {
flex-grow: 1;
position: relative;
width: 100%;
height: 100%;
}
.scrollable-content-wrapper {
position: absolute;
left: 0;
right: 0;
top: 0;
bottom: 0;
overflow: auto;
}
html {
height: 50%;
width: 50%;
}
body {
height: 100%;
width: 100%;
}
.parent {
height: 100%;
outline: 1px solid red;
}
<html>
<body>
<div class="parent">
<div class="flex-content">
<div class="scrollable-content-wrapper">
<div class="scrollable-content" id="scrollable">
1, 2, 3
</div>
</div>
</div>
</div>
<button onClick="scrollable.innerText += '\nSome more text'" style="margin-top: 1rem;">Add Line</button>
<p>
The red outline represents the parent. Click above to add a line until overflow occurs to see that the size of the parent is not increased.
</p>
</body>
</html>
I found a solution here:
http://www.sitepoint.com/maintain-image-aspect-ratios-responsive-web-design/
The trick is possible because it exists a relation between WIDTH and PADDING-BOTTOM of an element. So:
parent:
container {
height: 0;
padding-bottom: 66%; /* for a 4:3 container size */
}
child (remove all css related to width, i.e. width:100%):
img {
max-height: 100%;
max-width: 100%;
position: absolute;
display:block;
margin:0 auto; /* center */
left:0; /* center */
right:0; /* center */
}
You can use the property object-fit
.cover {
object-fit: cover;
width: 150px;
height: 100px;
}
Like suggested here
A full explanation of this property by Chris Mills in Dev.Opera
And an even better one in CSS-Tricks
It's supported in
Chrome 31+
Safari 7.1+
Firefox 36+
Opera 26+
Android 4.4.4+
iOS 8+
I just checked that vivaldi and chromium support it as well (no surprise here)
It's currently not supported on IE, but... who cares ? Also, iOS supports object-fit, but not object-position, but it will soon.
Here is a solution for a recently opened question marked as a duplicate of this question. The <img> tag was exceeding the max-height of the parent <div>.
Broken: Fiddle
Working: Fiddle
In this case, adding display:flex to the 2 parent <div> tags was the answer
Maybe someone else can explain the reasons behind your problem but you can solve it by specifying the height of the container and then setting the height of the image to be 100%. It is important that the width of the image appears before the height.
<html>
<head>
<style>
.container {
background: blue;
padding: 10px;
height: 100%;
max-height: 200px;
max-width: 300px;
}
.container img {
width: 100%;
height: 100%
}
</style>
</head>
<body>
<div class="container">
<img src="http://placekitten.com/400/500" />
</div>
</body>
</html>
The closest I can get to this is this example:
http://jsfiddle.net/YRFJQ/1/
or
.container {
background: blue;
border: 10px solid blue;
max-height: 200px;
max-width: 200px;
overflow:hidden;
box-sizing:border-box;
}
img {
display: block;
max-height: 100%;
max-width: 100%;
}
The main problem is that the height takes the percentage of the containers height, so it is looking for an explicitly set height in the parent container, not it's max-height.
The only way round this to some extent I can see is the fiddle above where you can hide the overflow, but then the padding still acts as visible space for the image to flow into, and so replacing with a solid border works instead (and then adding border-box to make it 200px if that's the width you need)
Not sure if this would fit with what you need it for, but the best I can seem to get to.
A good solution is to not use height on the parent and use it just on the child with View Port :
Fiddle Example: https://jsfiddle.net/voan3v13/1/
body, html {
width: 100%;
height: 100%;
}
.parent {
width: 400px;
background: green;
}
.child {
max-height: 40vh;
background: blue;
overflow-y: scroll;
}
Containers will already generally wrap their content nicely. It often doesn't work as well the other way around: children don't fill their ancestors nicely. So, set your width/height values on the inner-most element rather than the outer-most element, and let the outer elements wrap their contents.
.container {
background: blue;
padding: 10px;
}
img {
display: block;
max-height: 200px;
max-width: 200px;
}
http://jsfiddle.net/mpalpha/71Lhcb5q/
.container {
display: flex;
background: blue;
padding: 10px;
max-height: 200px;
max-width: 200px;
}
img {
object-fit: contain;
max-height: 100%;
max-width: 100%;
}
<div class="container">
<img src="http://placekitten.com/400/500" />
</div>
So, I've seen tons of questions about this, but I would like a personal example. I'm rather new to programming, so I may be a little stupid...
Anyway, I have two <div>s, one with id bg and the other with class player.
This is what it looks like:
The red box is the player, and the large image is the bg.
I need the player to start in the center of the bg.
The bg is 640px X 640px.
This is the code I have so far in my CSS file:
#bg {
width: 640px;
height: 640px;
top: 0;
left: 0;
}
.player {
position:relative;
background-color:#FF0000;
width: 32px;
height: 32px;
top: 0px;
left: 0px;
}
Try changing your stylesheet to:
#bg {
width: 640px;
height: 640px;
top: 0;
left: 0;
position: relative;
}
.player {
position: absolute;
background-color: #FF0000;
width: 32px;
height: 32px;
top: 320px;
left: 320px;
z-index: 1;
}
And your HTML should look like this:
<div id="bg">
<!-- your bd code here -->
<div class="player"></div>
</div>
position: relative is relative to where the object would be placed normally. In your example, it would normally come below the first div, so that's where it will stay. (In other words position: relative used with a positioning of 0 won't move the objet anywhere.)
You could add top: -320px; left: 320px. That would position it it the space of the first div. But maxksbd19's answer is probably the better solution for your ultimate goal.
I try and avoid absolute positioning as it does not adapt to the container size and a change to the container requires you to go through your css and change all the absolute values.
I would do the following
CSS:
#bg {
overflow: auto; /* stops the .player from from moving #bg down */
width: 640px;
height: 640px;
background-color: blue;
text-align: center; /* center child div in IE */
}
.player {
background-color: White;
width: 32px;
height: 32px;
margin: 0 auto; /* center div in parent for non IE browsers */
margin-top: 304px; /* 50% from top minus div size */
}
HTML:
<div id="bg">
<div class="player"></div>
</div>
Now you only have to keep track of the top margin of the child container.