This question already has answers here:
Why does position:relative; appear to change the z-index?
(2 answers)
Why setting absolutely positioned element's sibling as position:relative, brings it above the former?
(1 answer)
Closed 1 year ago.
I am trying to set the background of the body to an image using background-image, and I have content that I want to be placed on top of the image. In the CSS, I am setting the background using the body selector with the ::before pseudo-element; however, the image doesn't come in the background unless if I use z-index: -1. (I am using ::before because I want to fix the image to the viewport, and I don't want to do that in the regular body selector as that will fix all the content on the page and prevent me from scrolling through the content.)
body::before {
content: "";
position: fixed;
top: 0;
left: 0;
width: 100%;
height: 100%;
z-index: -1;
background-image: url(...);
}
form {
background: purple;
border-radius: 5px;
padding: 50px;
width: 40%;
margin: 0 auto;
}
<html>
<body>
<form></form>
</body>
</html>
My question is: Why do I need to set the z-index to -1 in order for the image to appear in the background? Why doesn't it appear in the background automatically "before" all the content? Isn't that what the purpose of ::before is?
A bit tricky part here. First ::before doesn't mean that this pseudo element goes precisely before form element. In fact this means create pseudo element before any children of form element. Vice versa for ::after. Second you set position: fixed; for ::before thats create new stacking context for it - simple this is the reason (not really check: Why does position:relative; appear to change the z-index?) why it overlaps the content of form element.
UPD
Probably you should use background-attachment: fixed; on body element https://www.w3schools.com/cssref/pr_background-attachment.asp
Related
Why in IE8, is the background color of a pesudo element flowing behind children of the parent? The text flows in front, but the background-color does not. Z-index did not seem to help any.
I haven't been able to determine if this is a bug in IE8 or not. It seems like this would have been a pretty common use-case, but I couldn't find many blog posts or SO questions related to it.
http://jsfiddle.net/VAg2E/
<div id="parent">
<img src="http://placehold.it/200x200">
</div>
#parent{ padding: 20px; }
#parent:before{
content: 'Behind the image';
position: absolute;
top: 0;
left: 0;
width: 100px;
height: 100px;
background-color: red;
}
Edit : A related Stack Overflow Question about Stacking Order
This is definitely a bug in IE8; since your :before pseudo-element is positioned, it should create a new stacking context and always be drawn on top of the img unless you give it a negative z-index (even then, the entire element should be drawn behind it, not just its background).
This issue also seems specific to stacking between :before and :after pseudo-elements and replaced elements like img. It looks like IE8 is treating replaced content differently in terms of stacking, but whatever it is doing, it's definitely not conforming to the spec.
As you're probably aware, this is fixed in IE9.
Have your exact same issue, the only thing you can do is force the stacking order via CSS and z-index. The only catch is that z-index is placed on child element starting from parent element, so you wont be able to do a proper logic order as #parent-element {z-index: 2} and #child-element {z-index: 1}, the z-index for the #child-element will just be set to level 1 as a separate stack order inside the #parent-element.
You can still set z-index for the #child-element with a -1 value, it will just get back the whole #parent-element stacking order.
So to recap:
#parent-element { z-index: 99;} /* or any arbitrary number fitting */
#child-element {z-index: -1;}
Also remember to give both elements a position: relative/absolute to enable the stacking order fo z-index
IE8 only supports pseudos if <!DOCTYPE> is declared. Source
#parent { padding: 20px; z-index: 2; }
#parent:before {
content: 'Behind the image';
position: absolute;
top: 0;
left: 0;
width: 100px;
height: 100px;
background-color: red;
z-index: -1;
}
I have a footer div with 100% width. It's about 50px high, depending on its content.
Is it possible to give that #footer a background image that kind of overflows this div?
The image is about 800x600px, and I want it to be positioned in the left bottom corner of the footer. It should work sort of like a background image for my website, but I've already set a background image on my body. I need another image positioned at the bottom left corner of my website and the #footer div would be perfect for that.
#footer {
clear: both;
width: 100%;
margin: 0;
padding: 30px 0 0;
background:#eee url(images/bodybgbottomleft.png) no-repeat left bottom fixed;
}
The image is set to the footer, however it doesn't overflow the div. Is it possible to make that happen?
overflow:visible doesn't do the job!
There is a very easy trick. Set padding of that div to a positive number and margin to negative
#wrapper {
background: url(xxx.jpeg);
padding-left: 10px;
margin-left: -10px;
}
I do not believe that you can make a background image overflow its div. Images placed in Image tags can overflow their parent div, but background images are limited by the div for which they are the background.
You can use a css3 psuedo element (:before and/or :after) as shown in this article
https://www.exratione.com/2011/09/how-to-overflow-a-background-image-using-css3/
Good Luck...
No, you can't.
But as a solid workaround, I would suggest to classify that first div as position:relative and use div::before to create an underlying element containing your image. Classified as position:absolute you can move it anywhere relative to your initial div.
Don't forget to add content to that new element. Here's some example:
div {
position: relative;
}
div::before {
content: ""; /* empty but necessary */
position: absolute;
background: ...
}
Note: if you want it to be 'on top' of the parent div, use div::after instead.
Using background-size cover worked for me.
#footer {
background-color: #eee;
background-image: url(images/bodybgbottomleft.png);
background-repeat: no-repeat;
background-size: cover;
clear: both;
width: 100%;
margin: 0;
padding: 30px 0 0;
}
Obviously be aware of support issues, check Can I Use: http://caniuse.com/#search=background-size
Use trasform: scale(1.1) property to make bg image bigger, move it up with position: relative; top: -10px;
<div class="home-hero">
<div class="home-hero__img"></div>
</div>
.home-hero__img{
position:relative;
top:-10px;
transform: scale(1.1);
background: {
size: contain;
image: url('image.svg');
}
}
You mention already having a background image on body.
You could set that background image on html, and the new one on body. This will of course depend upon your layout, but you wouldn't need to use your footer for it.
Not really - the background image is bounded by the element it's applied to, and the overflow properties only apply to the content (i.e. markup) within an element.
You can add another div into your footer div and apply the background image to that, though, and have that overflow instead.
This could help.
It requires the footer height to be a fixed number. Basically, you have a div inside the footer div with it's normal content, with position: absolute, and then the image with position: relative, a negative z-index so it stays "below" everything, and a negative top value of the footer's height minus the image height (in my example, 50px - 600px = -550px). Tested in Chrome 8, FireFox 3.6 and IE 9.
This question already has answers here:
How to get a child element to show behind (lower z-index) than its parent? [duplicate]
(7 answers)
Why can't an element with a z-index value cover its child?
(5 answers)
Closed 3 years ago.
I am trying to style a element with the :after pseudo element CSS selector
#element {
position: relative;
z-index: 1;
}
#element::after {
position:relative;
z-index: 0;
content: " ";
position: absolute;
width: 100px;
height: 100px;
}
It seems like the ::after element can not be lower then the element itself.
Is there a way to have the pseudo element lower then the element itself?
Pseudo-elements are treated as descendants of their associated element. To position a pseudo-element below its parent, you have to create a new stacking context to change the default stacking order.
Positioning the pseudo-element (absolute) and assigning a z-index value other than “auto” creates the new stacking context.
#element {
position: relative; /* optional */
width: 100px;
height: 100px;
background-color: blue;
}
#element::after {
content: "";
width: 150px;
height: 150px;
background-color: red;
/* create a new stacking context */
position: absolute;
z-index: -1; /* to be below the parent element */
}
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Position a pseudo-element below its parent</title>
</head>
<body>
<div id="element">
</div>
</body>
</html>
I know this is an old thread, but I feel the need to post the proper answer. The actual answer to this question is that you need to create a new stacking context on the parent of the element with the pseudo element (and you actually have to give it a z-index, not just a position).
Like this:
#parent {
position: relative;
z-index: 1;
}
#pseudo-parent {
position: absolute;
/* no z-index allowed */
}
#pseudo-parent:after {
position: absolute;
top:0;
z-index: -1;
}
#parent { position: relative; z-index: 1; }
#pseudo-parent { position: absolute; } /* no z-index required */
#pseudo-parent:after { position: absolute; z-index: -1; }
/* Example styling to illustrate */
#pseudo-parent { background: #d1d1d1; }
#pseudo-parent:after { margin-left: -3px; content: "M" }
<div id="parent">
<div id="pseudo-parent">
</div>
</div>
Try it out
el {
transform-style: preserve-3d;
}
el:after {
transform: translateZ(-1px);
}
There are two issues are at play here:
The CSS 2.1 specification states that "The :beforeand :after pseudo-elements elements interact with other boxes, such as run-in boxes, as if they were real elements inserted just inside their associated element." Given the way z-indexes are implemented in most browsers, it's pretty difficult (read, I don't know of a way) to move content lower than the z-index of their parent element in the DOM that works in all browsers.
Number 1 above does not necessarily mean it's impossible, but the second impediment to it is actually worse: Ultimately it's a matter of browser support. Firefox didn't support positioning of generated content at all until FF3.6. Who knows about browsers like IE. So even if you can find a hack to make it work in one browser, it's very likely it will only work in that browser.
The only thing I can think of that's going to work across browsers is to use javascript to insert the element rather than CSS. I know that's not a great solution, but the :before and :after pseudo-selectors just really don't look like they're gonna cut it here.
Speaking with regard to the spec (http://www.w3.org/TR/CSS2/zindex.html), since a.someSelector is positioned it creates a new stacking context that its children can't break out of. Leave a.someSelector unpositioned and then child a.someSelector:after may be positioned in the same context as a.someSelector.
I know this question is ancient and has an accepted answer, but I found a better solution to the problem. I am posting it here so I don't create a duplicate question, and the solution is still available to others.
Switch the order of the elements. Use the :before pseudo-element for the content that should be underneath, and adjust margins to compensate. The margin cleanup can be messy, but the desired z-index will be preserved.
I've tested this with IE8 and FF3.6 successfully.
Set the z-index of the :before or :after pseudo element to -1 and give it a position that honors the z-index property (absolute, relative, or fixed). This works because the pseudo element's z-index is relative to its parent element, rather than <html>, which is the default for other elements. Which makes sense because they are child elements of <html>.
The problem I was having (that lead me to this question and the accepted answer above) was that I was trying to use a :after pseudo element to get fancy with a background to an element with z-index of 15, and even when set with a z-index of 14, it was still being rendered on top of its parent. This is because, in that stacking context, it's parent has a z-index of 0.
Hopefully that helps clarify a little what's going on.
I fixed it very simple:
.parent {
position: relative;
z-index: 1;
}
.child {
position: absolute;
z-index: -1;
}
What this does is stack the parent at z-index: 1, which gives the child room to 'end up' at z-index: 0 since other dom elements 'exist' on z-index: 0. If we don't give the parent an z-index of 1 the child will end up below the other dom elements and thus will not be visible.
This also works for pseudo elements like :after
I don't know if someone will have the same issue with this. The selected answer is partially correct.
What you need to have is:
parent{
z-index: 1;
}
child{
position:relative;
backgr
Is there anyway for an absolute positioned child to expand to fill its relative positioned parent? (The height of parent is not fixed)
Here is what i did and it is working fine with Firefox and IE7 but not IE6. :(
<div id="parent">
<div id="child1"></div>
</div>
#parent { position: relative; width: 200px; height:100%; background:red }
#child1 { position: absolute; top: 0; left: 200px; height: 100%; background:blue }
That's easy. The trick is setting top: 0px and bottom: 0px at the same time
Here's the working code
html, body {
width: 100%;
height: 100%;
overflow: hidden;
}
#parent {
display: block;
background-color: #ff0;
border: 1px solid #f00;
position: relative;
width: 200px;
height: 100%;
}
#child1 {
background-color: #f00;
display: block;
border: 1px solid #ff0;
position: absolute;
left: 200px;
top: 0px;
bottom: 0px;
}
Check out a working example here http://jsfiddle.net/Qexhh/
If I remember correctly there is a bug with how IE6 handles div height. It will only create the div to the height needed to contain the content within it when height is set to 100%. I would recommend two approaches:
Don't worry about supporting IE6 as it is a dead browser anyway
If that doesn't work, use something like jQuery to get the height of the parent div and then set the child div to that height.
fake it by setting the backgrounds to be the same colour so no-one notices the difference
You can achieve this with setting both the top and bottom attributes of the child.
See how this is done
At the bottom of that article, there is a link to Dean Edwards' IE7 (and IE8) js library that you should include for IE6 visitors. It is a JS library that actually MAKES IE6 behave like IE7 (or 8) when you include it. Sweet!
Dean Edwars' IE7 and 8 JS libraries
As far as I know, there is no way of expanding a parent element around an absolutely positioned child element. By making the child element absolutely positioned your are removing it from the regular flow of page items.
I recently built a 2-column website where the right column was absolutely positioned but the left column was not. If the left column had less content and a smaller height than the right column, the page would cut off the right column since it was absolutely positioned.
In order to resolve this, I had to determine if the height of the right column was greater than the height of the left column and if so set the height of the parent div height to the greater of the two.
Here is my jQuery solution. I'm not much of a coder so feel free to tweak this:
jQuery(function(){
var rightColHeight = jQuery('div.right_column').height();
var leftColHeight = jQuery('div.left_column').height();
if (rightColHeight > leftColHeight){
jQuery('.content_wrap').height(rightColHeight+'px');
}
});
it can be done using javascript, but with CSS alone, is it possible to style a div to overlap exactly any page's document content or viewport (to apply an opaque gray layer on the page)? since a page can have margin for it body element, so styling a div to the width of its body element won't do. (needs to work in IE 6 too)
IF you have a <div> like this:
<div id="cover"></div>
These styles should do it:
#cover {
background-color: #ccc;
opacity: 0.6;
filter:alpha(opacity=60);
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
}
Tested on a page where the body has a margin and it covered the entire viewport for me on IE and FF.
height: 100% won't cover the viewport if document length is less than height of viewport. In this case you will have to use Javascript.
would it be cheating to use IE's ability to execute javascript in CSS?
width:expression(document.body.clientWidth)