<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> <style> .box2 { color: blue; } .box1 { color: red; } .box4 { color: yellow; } .box3 { color: green; } </style> </head> <body> <!-- <div class=" box1 box2"> hello world </div> --> <div class="box3"> <div class="box4">你好世界</div> </div> </body> </html>
