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What are the types of html5 positioning?
- 青灯夜游Original
- 2022-01-11 11:18:245393browse
html5 There are 5 types of positioning: 1. Absolute positioning (absolute); 2. Relative positioning (relative); 3. Fixed positioning (fixed); 4. Sticky positioning (sticky); 5. Static positioning (static) ).
The operating environment of this tutorial: Windows 7 system, HTML5 version, Dell G3 computer.
Several positioning methods in html5
position sets the position of the block-level element relative to its parent block and relative to itself where it should be Position
1. Absolute positioning(absolute)
Features:
If there is no parent element, the reference object is the entire Document
By default, the reference object is the positioned parent element
Adding an absolutely positioned element will break away from the entire layout flow and destroy it. Layout space
The absolutely positioned element is dragged out from the document flow and relative to its closest parent element with the most positioning settings using attributes such as left, right, top, bottom etc. For absolute positioning, if the element's parent does not set the positioning attribute, positioning will be based on the upper left corner of the body element as a reference. Absolutely positioned elements can be stacked, and the stacking order can be controlled through the z-index attribute. The z-index value is a unitless integer, with the larger one on top, and can have negative values.
Absolute positioning positioning method: If its parent element sets a position other than static, such as position:relative or position:absolute and position:fixed, then it will be relative to its parent element. Positioning and position are specified by the left, top, right, and bottom attributes. If its parent element does not have positioning set, then it depends on whether the parent element of its parent element has positioning set. If it still does not, continue to the higher-level ancestor element. By analogy, in short, its positioning is relative to the first ancestor element that has a positioning other than static positioning. If all ancestor elements do not have one of the above three positionings, then it will be relative to the document. body to position (not relative to the browser window, positioning relative to the window is fixed).
<head>
<style type="text/css">
.box {
background: red;
width: 100px;
height: 100px;
float: left;
margin: 5px;
}
.two {
position: absolute;
top: 50px;
left: 50px;
}
</style>
</head>
<body>
<div class="box" >One</div>
<div class="box two" >Two</div>
<div class="box" >Three</div>
<div class="box">Four</div>
</body>Position the div with class="two" 50px from the top and left of
. It will change the layout of other elements and will not leave any blank space in the original position of this element.
#2. Relative positioning (relative is equivalent to the scene of an out-of-body experience)
Features:
The reference object is its own default position
Occupies space
Will not destroy the layout flow
Relatively positioned elements cannot be stacked and can be offset in the normal document flow based on attributes such as left, right, top, and bottom. You can also use z-index hierarchical design.
<head>
<style type="text/css">
.box {
background: red;
width: 100px;
height: 100px;
float: left;
margin: 5px;
}
.two {
position: relative;
top: 50px;
left: 50px;
}
</style>
</head>
<body>
<div class="box" >One</div>
<div class="box two" >Two</div>
<div class="box" >Three</div>
<div class="box">Four</div>
</body>Position the div with class="two" 50px from the top and left of its original position. It will not change the layout of other elements, but will leave a blank space in the original position of this element.
3. Fixed positioning (fixed)
Features:
Reference object Fixed positioning for the browser window
Fixed positioning is similar to absolute positioning, but it is positioned relative to the browser window and does not scroll with the scroll bar.
One of the most common uses of fixed positioning is to create a fixed header, fixed foot or fixed sidebar on the page, without using margin, border, or padding.
How to center an element on the left, right, top and bottom of the browser window:
Method one:
position:fixed left:50%; top:50%; margin-left: -盒子宽度的一半 margin-top:-盒子高度的一半
Method two:
position:fixed; left:0; right:0 top:0 bottom:0 margin:auto
4. Sticky positioning (sticky has compatibility issues)
Features:
It is a combination of relative and fixed
When the page does not trigger the scroll bar, the execution effect is position: relative, otherwise the execution effect is position: fixed
-
The application is: page ceiling
<!DOCTYPE html>
<html>
<meta charset="utf8">
<head>
<style>
section:first-child {
height: 200px;
background-color: lightgray;
}
section:nth-child(2) {
height: 100px;
background-color: orange;
position: sticky;
position: -webkit-sticky;
top: 50px;
}
section:nth-child(3) {
height: 300px;
background-color: lightgray;
}
section:nth-child(4) {
height: 100px;
background-color: orange;
position: sticky;
position: -webkit-sticky;
top: 150px;
}
section:last-child {
height: 500px;
background-color: darkgray;
}
</style>
</head>
<body>
<section>SECTION-1</section>
<section>SECTION-2</section>
<section>SECTION-3</section>
<section>SECTION-4</section>
<section>SECTION-5</section>
</body>
</html>
5. Static positioning (static default)
When you do not specify for an element (such as div) The positioning method defaults to static, which means that the element is positioned in a suitable place according to the flow of the document. Therefore, under different resolutions, the use of flow positioning can be well adapted and achieve relatively good layout effects.
Generally speaking, we do not need to specify that the positioning method of the current element is static - because this is the default positioning method. Unless you want to override the positioning system inherited from the parent element.
The left and top attributes have no effect on static, which is positioned by margin.
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