Correcting teacher:天蓬老师
Correction status:qualified
Teacher's comments:
1.静态定位:
position(static)
默认,也就是文档流的定位,元素的显示位置与源码顺序一致2.相对定位:
position(relative)
,相对于元素在文档流中的元素位置进行偏移3.绝对定位:
position(absolue)
,相对于它的祖先中离它最近的”定位元素”的位置进行偏移4.固定定位:
position(fixed)
,是绝对定位的一个特例,它始终相对于html定位
如果祖先元素中不存在定位元素,它就参照根元素(html)进行定位position(static)
不是定位元素
只有定位元素才有资格充当绝对定位元素的定位祖先元素(定位参考元素,定位父级)
相对定位:position(relative)
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>定位的种类</title>
<style>
* {
padding: 0;
margin: 0;
box-sizing: border-box;
}
.box {
width: 15em;
height: 15em;
border: 1px solid red;
margin: 2em auto;
}
.box h2 {
border: 1px solid black;
background-color: skyblue;
/* 使用相对定位 */
position: relative;
top: 1em;
left: 1em;
}
</style>
</head>
<body>
<div class="box">
<h2>Hello World</h2>
<p>广告位广告位广告位!</p>
</div>
</body>
</html>
演示截图
绝对定位并完全覆盖父元素 :position(absolue)
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>定位的种类</title>
<style>
* {
padding: 0;
margin: 0;
box-sizing: border-box;
}
.box {
width: 15em;
height: 15em;
border: 1px solid red;
margin: 2em auto;
}
.box {
position: relative;
}
.box h2 {
border: 1px solid violet;
background-color: skyblue;
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
}
</style>
</head>
<body>
<div class="box">
<h2>Hello World</h2>
<p>广告位广告位广告位!</p>
</div>
</body>
</html>
演示截图
固定定位实现右下角广告: position(fixed)
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>定位的种类</title>
<style>
* {
padding: 0;
margin: 0;
box-sizing: border-box;
}
.box {
width: 15em;
height: 15em;
border: 1px solid red;
margin: 2em auto;
}
.box {
position: relative;
}
.box h2 {
border: 1px solid violet;
background-color: skyblue;
position: fixed;
bottom: 0;
right: 0;
}
html {
min-height: 100em;
}
</style>
</head>
<body>
<div class="box">
<h2>Hello World</h2>
<p>广告位广告位广告位!</p>
</div>
</body>
</html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>固定定位实现:模态框</title>
<style>
* {
padding: 0;
margin: 0;
box-sizing: border-box;
}
header {
background-color: skyblue;
overflow: hidden;
}
header h2 {
float: left;
}
header button {
height: 3em;
width: 10em;
float: right;
}
header button:hover {
cursor: pointer;
background-color: #fff;
}
.close {
float: right;
height: 2.5em;
width: 3em;
border: 0;
border-radius: 0.5em;
outline: none;
background-color: rgb(1, 231, 135);
}
.close:hover {
background-color: #eee;
}
/* 蒙版 */
.modal .modal-backdrap {
background-color: rgb(0,0,0,0.5);
position: fixed;
top: 0;
left: 0;
right: 0;
bottom: 0;
}
.modal .modal-body {
padding: 1em;
min-width: 20em;
border-radius: 0.5em;
border: 1px solid rgb(255, 255, 255);
background: linear-gradient(to right,rgb(54, 206, 252),violet);
/* 固定定位 */
position: fixed;
top: 5em;
left: 30em;
right: 30em;
}
.dl {
margin: 0.5em 5em ;
height: 2em;
width: 8em;
outline: none;
border: 0;
border-radius: 0.5em;
background-color: rgb(17, 255, 215);
}
.dl:hover{
background-color: #fff;
}
.modal {
display: none;
}
</style>
</head>
<body>
<header>
<h2>我的博客</h2>
<button>登录</button>
</header>
<div class="modal">
<!-- 蒙版 -->
<div class="modal-backdrap"></div>
<!-- 主体 -->
<div class="modal-body">
<button class="close">关闭</button>
<form action="" method="POST">
<h2>用户登录</h2>
<label>账号:</label>
<input type="text" name="user" id="user" value="" placeholder="请输入用户名" /><br>
<label>密码:</label>
<input type="password" name="password" id="password" value="" placeholder="请输入密码" /><br>
<button class="dl">登录</button>
</form>
</div>
</div>
<script src="modal.js"></script>
</body>
</html>
演示截图