<!-- 垂直居中一定要有确定大小的 父容器(根) html,body 一般100% --> <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>index</title> <style> html, body { width: 100%; height: 100%; margin: 0; padding: 0; } body { display: flex; /*定义body的元素垂直居中*/ align-items: center; /*定义body的里的元素水平居中*/ justify-content: center; } .content { width: 300px; height: 300px; background: orange; } </style> </head> <body> <div class="content"></div> </body> </html>