在css加载失败的时候 提高用户体验
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
h1 {
margin: 0;
}
.logo {
width: 142px;
height: 58px;
}
.logo h1 .logo-hd {
display: block;
width: 142px;
height: 0;/*不设置高度防止文字与图片重叠 */
padding-top: 58px; /* 用内边距撑开 */
background: url(img/logo.jpg) no-repeat 0 0/142px 58px;
overflow: hidden;
}
</style>
</head>
<body>
<div class="logo">
<h1>
<a href="" class="logo-hd"> 淘宝网 </a>
</h1>
</div>
</body>
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
</style>
</head>
<body>
<div class="logo">
<h1>
<a href="" class="logo-hd"> 淘宝网 </a>
</h1>
</div>
</body>
table上的border
在table上直接设置border与设置css样式border有什么区别
答 直接设置 单元格也有变宽 设置css样式只能table整体有边框
caption-side
表格标题caption的位置
top 在表格上面
bottom 在表格下面
border-collapse
默认值separation 表格边框不合并
collapse 合并表格的边框
table-layout
单元格的宽度保持一致
table-layout:fixed 内容再多也不会改变单元格宽度 而是会换行
automatic 默认值
bfc
如何让元素成为bfc元素
body本身就是bfc元素
float 定义为为left right
position 定义为absolute fixed
display 定义为inline-block table-ceil
flex 布局
overflow 定义为hidden auto scroll
1.解决margin合并的问题
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
.box1 {
width: 100px;
height: 100px;
background-color: green;
margin-bottom: 100px;
}
.box2 {
width: 100px;
height: 100px;
background-color: orange;
margin-top: 100px;
}
</style>
</head>
<body>
<div class="box1"></div>
<div class="box2"></div>
</body>
</html>
给两个盒子套上开启bfc的元素
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
.container {
overflow: hidden;
}
.box1 {
width: 100px;
height: 100px;
background-color: green;
margin-bottom: 100px;
}
.box2 {
width: 100px;
height: 100px;
background-color: orange;
margin-top: 100px;
}
</style>
</head>
<body>
<div class="container">
<div class="box1"></div>
</div>
<div class="contaniner">
<div class="box2"></div>
</div>
</body>
</html>
2.解决高度塌陷的问题
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
.box {
width: 200px;
border: 10px solid #000;
}
.box1 {
float: left;
width: 100px;
height: 100px;
background-color: green;
}
.box2 {
float: left;
width: 100px;
height: 100px;
background-color: orange;
}
</style>
</head>
<body>
<div class="box">
<div class="box1"></div>
<div class="box2"></div>
</div>
</body>
</html>
使父级元素开启bfc
.box {
width: 200px;
border: 10px solid #000;
overflow: hidden
}
3.解决margin塌陷问题
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
.box1 {
width: 300px;
height: 300px;
background-color: #000;
}
.box2 {
width: 50px;
height: 50px;
margin: 0 auto;
margin-top: 100px;
background-color: orange;
}
</style>
</head>
<body>
<div class="box1">
<div class="box2"></div>
</div>
</body>
</html>
父级元素开启bfc
.box1 {
width: 300px;
height: 300px;
background-color: #000;
overflow: hidden;
}
4.解决浮动元素覆盖的问题
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
.box1 {
float: left;
width: 100px;
height: 100px;
background-color: #000;
}
.box2 {
width: 200px;
height: 290px;
background-color: orange;
}
</style>
</head>
<body>
<div class="box1">我是box1</div>
<div class="box2">
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</div>
</body>
</html>
给环绕元素开启bfc
.box2 {
display: table-cell;
width: 200px;
height: 290px;
background-color: orange;
}
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