Navicon Transformicons: Animated Navigation Icons with CSS Transforms
http://sarasoueidan.com/blog/navicon-transformicons/
CSS3 box-shadow
http://www.w3cplus.com/content/css3-box-shadow
<!DOCTYPE html> <html lang="zh-CN"> <head> <meta charset="utf-8"> <title></title> <style> button {display: inline-block;margin: 0 1em;border: none;background: none;background: #000;} button span {display: block;} .grid-button {padding: 2rem;cursor: pointer;user-select: none;} .grid-button .grid {width: 1rem;height: 1rem;background: #ecf0f1;color: #ecf0f1;transition: 0.3s;} .grid-button.collapse .grid {box-shadow: -1.25rem 0, -1.25rem 1.25rem, 1.25rem 0, 1.25rem -1.25rem, 0 -1.25rem, -1.25rem -1.25rem, 0 1.25rem, 1.25rem 1.25rem;} </style> </head> <body> <button type="button" role="button" aria-label="Toggle Navigation" class="grid-button collapse"> <span class="grid"></span> </button> </body> </html>