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一、实例演示相邻选择器与兄弟选择器,并分析异同
<!DOCTYPE html> <html lang="zh_CN"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>相邻选择器与兄弟选择器</title> <link rel="stylesheet" href="demo03a.css"> </head> <body> <ul> <li class="testclass">1</li> <li id="testid01">2</li> <li class="testclass">3</li> <li class="testclass">4</li> <li id="testid02">5</li> <li>6</li> <li>7</li> <li>8</li> <li>9</li> <li>10</li> </ul> </body> </html>
点击 "运行实例" 按钮查看在线实例
/* demo03a.css */
ul {
margin: 0;
padding-left: 0;
border: 1px dashed red;
}
ul li {
list-style-type: none;
width: 40px;
height: 40px;
background-color: wheat;
border: 1px solid black;
/* 水平和垂直居中 */
text-align: center;
line-height: 40px;
border-radius: 50%;
/* 将块元素转换为内联元素 */
display: inline-block;
box-shadow: 2px 2px 1px #777;
}
/* 相邻选择器 */
#testid01+* {
background-color: blue;
}
/* 兄弟选择器 */
#testid02~* {
background-color: red;
}点击 "运行实例" 按钮查看在线实例
二、实例演示:nth-child() 和 :nth-of-type()选择器,并分析异同
<!DOCTYPE html> <html lang="zh_CN"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>子类选择器与类型选择器</title> <link rel="stylesheet" href="demo03b.css"> </head> <body> <ul> <li class="testclass">1</li> <li id="testid01">2</li> <li class="testclass">3</li> <li class="testclass">4</li> <li id="testid02">5</li> <li>6</li> <li>7</li> <li>8</li> <li>9</li> <li>10</li> </ul> </body> </html>
点击 "运行实例" 按钮查看在线实例
/* demo03b.css */
ul {
margin: 0;
padding-left: 0;
border: 1px dashed red;
}
ul li {
list-style-type: none;
width: 40px;
height: 40px;
/* background-color: wheat; */
border: 1px solid black;
/* 水平和垂直居中 */
text-align: center;
line-height: 40px;
border-radius: 50%;
/* 将块元素转换为内联元素 */
display: inline-block;
box-shadow: 2px 2px 1px #777;
}
/* 伪类：子元素选择器 */
ul :first-child {
background-color: #ff0;
}
ul :nth-child(6) {
background-color: #0ff;
}
/* 伪类：类型选择器 */
ul li:nth-of-type(9) {
background-color: #0f0;
}点击 "运行实例" 按钮查看在线实例
三、实例演示:padding 对盒子大小的影响与解决方案, 使用宽度分离或box-sizing
<!DOCTYPE html>
<html lang="zh_CN">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>padding对盒子大小的影响与解决方案</title>
<style>
/* box-sizing设置为border-box，限定基准为边框 */
.box1 {
width: 400px;
box-sizing: border-box;
padding: 50px;
background-color: #f00;
border: 1px solid blue;
}
</style>
</head>
<body>
<div class="box1">
<img src="./test01.png" alt="中秋快乐" ">
</div>
</body>
</html>点击 "运行实例" 按钮查看在线实例
四、实例演示: margin中的同级塌陷, 嵌套传递与自动挤压, 并提出解决方案或应用场景
<!DOCTYPE html>
<html lang="zh_CN">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>margin中的同级塌陷, 嵌套传递与自动挤压</title>
<style>
/* box1与box2同级塌陷 */
.box1 {
width: 200px;
height: 200px;
background-color: #00f;
margin-bottom: 50px;
}
.box2 {
width: 300px;
height: 250px;
background-color: #f00;
margin-top: 30px;
}
/* box3与box4嵌套传递*/
.box3 {
width: 200px;
height: 200px;
background-color: lightgreen;
}
.box4 {
width: 150px;
height: 100px;
background-color: lightcoral;
margin-top: 30px;
}
.box5 {
width: 250px;
height: 100px;
background-color: #ffff00;
margin: auto;
}
</style>
</head>
<body>
<div class="box1"></div>
<div class="box2"></div>
<div class="box3">
<div class="box4"></div>
</div>
<div class="box5"></div>
</body>
</html>点击 "运行实例" 按钮查看在线实例
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