1.css文件：
div{border: 1px solid red;}span{border: 4px solid green;}
html文件:
<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>Title</title><!--link标签专门用来引入css样式代码--><link rel="stylesheet" type="text/css" href="1.css"/></head><body><div>div标签1</div><div>div标签2</div><div>div标签2</div><div>div标签2</div><div>div标签2</div><div>div标签2</div><span>span标签1</span><span>span标签2</span><span>span标签2</span><span>span标签2</span><span>span标签2</span></body></html>
