1、打开WebStrom开发工具，新建test.html文件
3、引入bootstrap4样式文件，代码如下：<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <link rel="stylesheet" href="bootstrap4.0dist/css/bootstrap.min.css"> <title>Title</title></head><body> <div class="bg-dark text-white">hello world</div></body></html>
5、修改代码设置div的宽度，代码如下：<!DOCTYPE html><html lang="en"媪青怍牙><head> <meta charset="UTF-8"> <link rel="stylesheet" href="bootstrap4.0dist/css/bootstrap.min.css"> <title>Title</title></head><body> <div class="bg-dark text-white w-25">hello world</div></body></html>这里的w-25是指宽度占百分之二十五
7、修改代码，设置div的高度，注意这里外面在套一个div，h-50是指占高度占外层div的百分之五十，代码如下：<!DOCTYPE html><茑霁酌绡html lang="en"><head> <meta charset="UTF-8"> <link rel="stylesheet" href="bootstrap4.0dist/css/bootstrap.min.css"> <title>Title</title></head><body> <div style="width:4000px;height: 100px"> <div class="bg-dark text-white w-25 h-50">hello world</div> </div></body></html>
