The z-index attribute is an attribute used in CSS to set the stacking order of elements. Elements with a higher stacking order will always be in front of elements with a lower stacking order, and elements can have negative The z-index attribute value.
The operating environment of this article: Windows 7 system, Dell G3 computer, css3 version.
z-index attribute sets the stacking order of elements. Elements with a higher stacking order will always appear in front of elements with a lower stacking order.
Note: Elements can have negative z-index attribute values.
Note: Z-index only works on positioned elements (such as position:absolute;)!
Description
This property sets the position of a positioned element along the z-axis, which is defined as the axis that extends vertically to the display area. If it is a positive number, it is closer to the user, and if it is a negative number, it is further away from the user.
Default value: auto
Inheritance: no
Version: CSS2
JavaScript Syntax: object.style.zIndex="1"
Possible values
auto Default. The stacking order is equal to the parent element.
number Set the stacking order of elements.
inherit specifies that the value of the z-index attribute should be inherited from the parent element.
[Recommended learning: css video tutorial]
Example
Set the z-index of the image:
<html>
<head>
<style type="text/css">
img
{
position:absolute;
left:0px;
top:0px;
z-index:-1;
}
</style>
</head>
<body>
<h1 id="This-nbsp-is-nbsp-a-nbsp-heading">This is a heading</h1>
<img src="/static/imghwm/default1.png" data-src="/i/eg_smile.gif" class="lazy" / alt="What is the z-index attribute?" >
<p>由于图像的 z-index 是 -1，因此它在文本的后面出现。</p>
</body>
</html> Effect:
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