效果图
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>index</title> <style> ul { display: flex; width: 800px; list-style: none; } li { position: relative; padding: 20px; transition: .2s all linear; cursor: pointer; } li::before { content: ""; position: absolute; top: 0; left: 100%; width: 0; height: 100%; border-bottom: 2px solid #000; transition: 0.2s all linear; } li:hover::before { width: 100%; left: 0; transition-delay: .1s; } li:hover ~ li::before { left: 0; } </style> </head> <body> <ul> <li>不可思议的CSS</li> <li>导航栏</li> <li>光标小下划线跟随</li> <li>PURE CSS</li> <li>Nav Underline</li> <li>cyy demo</li> </ul> </body> </html>