Correction status:qualified
Teacher's comments:学习一定要有总结, 才会有进步
1.内边距:增加padding盒子会被撑开。解决的三种办法:(1)增加padding之后重新设置盒子宽高,是宽高加padding等于原先的宽高。(2)宽度分离;给盒子增加一个***。嵌套盒子只会继承他宽度,然后设置padding(3)box-sizing 利用box-sizing将父级盒子的宽度作用于边框上而不是内容上,将宽度作用于边框上之后,padding就不会被撑开。
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <link rel="stylesheet" href="static/css/xxxx2.css"> <title>内边距padding</title> </head> <body> <div class="box1"> <img src="static/images/girl.jpg" alt="小女孩" width="200px"> </div> <hr> <div class="wrap"> <div class="box2"> <img src="static/images/girl.jpg" alt="小女孩" width="200px"> </div> </div> <!--<hr> 子盒作用父盒子的内容--> <hr> <div class="box3"> <img src="static/images/girl.jpg" alt="小女孩" width="200px"> </div> </div> </body> </html> .box1 { width: 300px; height: 300px; background-color: yellowgreen; border: 1px solid black; padding-left: 50px; } .box1 { padding: 50px; } .box1 { width: 200px; height: 200px; } /*嵌套盒子之间,只有宽度可以继承。*/ .wrap{ width:300px; } .box2{ height: 300px; background-color: blueviolet; border: 1px solid black; padding: 50px; } .box3 { width: 300px; box-sizing: border-box; /*将父盒子的宽度作用于边框上而不是内容上。*/ background-color: blueviolet; border: 2px solid black; padding: 50px; /*作用到边框上,盒子不会撑开*/ }
点击 "运行实例" 按钮查看在线实例
2.外边距:(1)同级塌陷(2)嵌套传递(3)自动挤压 同级塌陷只是上下塌陷,左右是重叠
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <link rel="stylesheet" href="static/css/xxxx3.css"> <title>margin外边距</title> </head> <body> <!--1.同级塌陷--> <!--2嵌套传递--> <!--3.自动挤压--> <!--1.同级塌陷--> <div class="box1"></div> <div class="box2"></div> <hr> <!--2嵌套传递--> <div class="box3"> <div class="box4"></div> </div> <hr> <!--3.自动挤压--> <div class="box5"></div> </body> </html> .box1 { width: 100px; height: 100px; background-color: blueviolet; } .box2 { width: 100px; height: 100px; background-color: red; } .box1{ margin-bottom: 30px; } .box2{ margin-bottom: 30px; } .box2{ margin-top: 50px; } /*小的会塌陷到大的里面,已大的为准。左右叠加,上下塌陷*/ .box3 { width: 200px; height: 200px; background-color: yellowgreen; } .box4 { width: 100px; height: 100px; background-color: yellow; } .box4 { margin-top: 0px; } .box3 { padding-top: 30px; height: 170px; } .box5 { width: 100px; height: 100px; background-color: royalblue; margin-left: auto; margin-right: auto; margin: 50px auto; }
点击 "运行实例" 按钮查看在线实例
3.浮动:(1)文档流 html元素默认按照书写的顺序在浏览器中,遵循先从左到右、在从上到下的顺序。(2)布局前提:通常先将元素从文档流中脱离出来,这样才能按照自己的要求布局(3)布局手段:浮动和绝对定位。
清除浮动:clean:both;
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <link rel="stylesheet" href="static/css/xxxx4.css"> <title>浮动</title> </head> <body> <!--1.文档流 html元素默认按照书写的顺序在浏览器中,遵循先从左到右、在从上到下的顺序。--> <!--2.布局前提:通常先将元素从文档流中脱离出来,这样才能按照自己的要求布局--> <!--3.布局手段:浮动和绝对定位。--> <!--浮动的基本原理--> <div class="box1"></div> <div class="box2"></div> <div class="box3"></div> <div class="box4"></div> </body> </html> box1 { width: 100px; height: 100px; background-color: royalblue; } .box2 { width: 150px; height: 150px; background-color: rosybrown; } /*元素浮动之后就脱离了文档流*/ .box1 { float: left; } .box2 { float: left; } .box3 { width:200px; height: 300px; background-color: tomato; } .box3 { float: right; } .box4 { width:100%; height: 50px; background-color: black; } .box4 { clear: left; clear: right; } .box4 { clear: both; }
点击 "运行实例" 按钮查看在线实例
4.定位:(1)静态定位: 浏览器默认方式, 即文档流中的位置(2)相对定位:元素并未脱离文档流,只是相对于它原来的位置,做相对移动(3)绝对定位: 元素脱离文档流重新排列,不论元素之前是什么类型,全部转为块元素,支持宽高(4)固定定位: 始终相对于浏览器的窗口做为定位父级,进行定位。相对定位是相对该元素自己原来的位置
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <link rel="stylesheet" href="static/css/xxxx7.css"> <title>php中文网登录页面</title> </head> <body> <div class="shade"></div> <div class="login" ><img src="static/images/login.jpg" alt=""></div> </body> </html> body { margin: 0; background-image: url("../images/php.jpg"); background-size: cover; background-repeat: no-repeat; } .shade { position: absolute; left: 0; top: 0; width: 100%; height: 100%; background-color: black; opacity: 0.7; } .login img{ width: 380px; height: 460px; background-color: white; position: absolute; left: 50%; top:50%; margin-left: -190px; margin-top: -230px; }
点击 "运行实例" 按钮查看在线实例
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <link rel="stylesheet" href="static/css/xxxx8.css"> <title>固定定位</title> <!--相对于body--> </head> <!--相对定位是相对该元素自己原来的位置--> <body> <div class="ads"> <button >x</button> <h2>php中文网开课啦</h2> <h3>招生进行中。。。</h3> </div> </body> </html> body { height: 2000px; } .ads { width: 300px; height: 300px; background-color: bisque; position: fixed; right: 0; bottom: 0; } .ads button { background-color: red; }
点击 "运行实例" 按钮查看在线实例
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <link rel="stylesheet" href="static/css/xxxx5.css"> <title>定位</title> </head> <body > <!--relative相对,未脱离文档流,相对于body--> <!--<div style="width: 100px;height: 100px;background-color: yellow;position: relative;top: 50px;left: 30px"></div>--> <div class="box1">1</div> <div class="box2">2</div> <div class="box3">3</div> <div class="box4">4</div> <div class="box5">5</div> </body> </html> .box1 { width: 100px; height: 100px; background-color: yellow; } .box2{ width: 100px; height: 100px; background-color: red; } .box3 { width: 100px; height: 100px; background-color: darkviolet; } .box4 { width: 100px; height: 100px; background-color: green; } .box5 { width: 100px; height: 100px; background-color: palevioletred; } .box1 { position: relative; left: 100px; } .box3 { position: relative; left: 100px; top: -100px; } .box4 { position: relative; left: 200px; top: -200px; } .box5 { position: relative; left: 100px; top: -200px; }
点击 "运行实例" 按钮查看在线实例
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <link rel="stylesheet" href="static/css/xxxx6.css"> <title>定位</title> </head> <body > <!--relative相对,未脱离文档流,相对于body--> <!--<div style="width: 100px;height: 100px;background-color: yellow;position: relative;top: 50px;left: 30px"></div>--> <div class="parent"> <div class="box1">1</div> <div class="box2">2</div> <div class="box3">3</div> <div class="box4">4</div> <div class="box5">5</div> </div> </body> </html> .parent { border: 1px dotted black; width: 300px; height: 300px; } .parent { position: relative; } .box1 { width: 100px; height: 100px; background-color: yellow; } .box2{ width: 100px; height: 100px; background-color: red; } .box3 { width: 100px; height: 100px; background-color: darkviolet; } .box4 { width: 100px; height: 100px; background-color: green; } .box5 { width: 100px; height: 100px; background-color: palevioletred; } .box1 { position: absolute; left: 100px; } .box2 { position: absolute; top: 100px; } .box3 { position: absolute; left: 100px; top: 100px; } .box4 { position: absolute; left: 200px; top: 100px; } .box5 { position: absolute; top: 200px; left: 100px; }
点击 "运行实例" 按钮查看在线实例