在B站上看到个不错的小特效，自己模仿者写了一下，触发事件都很明了了，大家一看就会明白的
效果如下：
<!DOCTYPE html><html> <head> <meta charset="UTF-8"> <title>shade box</title> <style type="text/css"> * { margin: 0px; padding: 0px; box-sizing: border-box; font-family: 'Microsoft Yahei'; font-size: 14px; } nav { width: 500px; margin: 10px auto; } .nav { list-style: none; } .nav li { float: left; margin: 0px 5px; } .nav_element { position: relative; } /*过度时间为0.5s*/ .shade { position: absolute; left: 0px; top: 0px; transition: 0.5s; width: 0px; height: 20px; border-radius: 5px 5px; /* 遮罩起始宽度为0 溢出隐藏*/ overflow: hidden; z-index: 1; visibility: hidden; } /*外廓事先已经画好 只是以为父容器宽度为0溢出隐藏不可视而已*/ .outer { position: absolute; left: 0px; top: 0px; width: 60px; height: 20px; border: 1px solid #00a1d6; border-radius: 20px 20px; } /*z-index -1 让外廓可以覆盖此边线*/ .content { border:1px solid #ccc; width: 60px; height: 20px; border-radius: 20px 20px; text-align: center; line-height: 20px; background-color: #fff; position: relative; z-index: -1; } </style> </head> <body> <nav> <ul> <li> <div onmouseover="showOuter(this)" onmouseout="hideOuter(this)"> <div> <div></div> </div> <p>首页</p> </div> </li> <li> <div onmouseover="showOuter(this)" onmouseout="hideOuter(this)"> <div> <div></div> </div> <p>视频</p> </div> </li> <li> <div onmouseover="showOuter(this)" onmouseout="hideOuter(this)"> <div> <div></div> </div> <p>新闻</p> </div> </li> <li> <div onmouseover="showOuter(this)" onmouseout="hideOuter(this)"> <div> <div></div> </div> <p>画廊</p> </div> </li> <li> <div onmouseover="showOuter(this)" onmouseout="hideOuter(this)"> <div> <div></div> </div> <p>直播</p> </div> </li> <li> <div onmouseover="showOuter(this)" onmouseout="hideOuter(this)"> <div> <div></div> </div> <p>One</p> </div> </li> <li> <div onmouseover="showOuter(this)" onmouseout="hideOuter(this)"> <div> <div></div> </div> <p>Enge</p> </div> </li> </ul> <script type="text/javascript"> //获取某导航元素的遮罩子元素 修改其宽度 function showOuter(nav_element) { var shade = nav_element.getElementsByClassName('shade')[0]; shade.style.visibility = 'visible'; shade.style.width = '60px'; } function hideOuter(nav_element) { var shade = nav_element.getElementsByClassName('shade')[0]; shade.style.visibility = 'hidden'; shade.style.width = '0px'; } </script> </nav> </body></html>
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