CSS3伪类如何做3D按钮的实例分析

 <p id="container_buttons">
 <p><a class="a_demo_three">点我！</a></p>
 <p><a class="a_demo_three second_button">来嘛，别害怕！</a></p>
 <p><a class="a_demo_three third_button">秋叶网络博客（www.mizuiren.com）</a></p>
 </p>

 #container_buttons{cursor:pointer;}
 .a_demo_three {
 background-color:#3bb3e0;
 font-family: 'Open Sans', sans-serif;
 font-size:12px;
 text-decoration:none;
 color:#fff;
 position:relative;
 padding:10px 20px;
 border-left:solid 1px #2ab7ec;
 margin-left:35px;
 background-image: linear-gradient(bottom, rgb(44,160,202) 0%, rgb(62,184,229) 100%);
 background-image: -o-linear-gradient(bottom, rgb(44,160,202) 0%, rgb(62,184,229) 100%);
 background-image: -moz-linear-gradient(bottom, rgb(44,160,202) 0%, rgb(62,184,229) 100%);
 background-image: -webkit-linear-gradient(bottom, rgb(44,160,202) 0%, rgb(62,184,229) 100%);
 background-image: -ms-linear-gradient(bottom, rgb(44,160,202) 0%, rgb(62,184,229) 100%);
 background-image: -webkit-gradient(linear,left bottom,left top,color-stop(0, rgb(44,160,202)),color-stop(1, rgb(62,184,229)));
 -webkit-border-top-right-radius: 5px;
 -webkit-border-bottom-right-radius: 5px;
 -moz-border-radius-topright: 5px;
 -moz-border-radius-bottomright: 5px;
 border-top-right-radius: 5px;
 border-bottom-right-radius: 5px;
 -webkit-box-shadow: inset 0px 1px 0px #2ab7ec, 0px 5px 0px 0px #156785, 0px 10px 5px #999;
 -moz-box-shadow: inset 0px 1px 0px #2ab7ec, 0px 5px 0px 0px #156785, 0px 10px 5px #999;
 -o-box-shadow: inset 0px 1px 0px #2ab7ec, 0px 5px 0px 0px #156785, 0px 10px 5px #999;
 box-shadow: inset 0px 1px 0px #2ab7ec, 0px 5px 0px 0px #156785, 0px 10px 5px #999;
 }
 .a_demo_three:active {
 top:3px;
 background-image: linear-gradient(bottom, rgb(62,184,229) 0%, rgb(44,160,202) 100%);
 background-image: -o-linear-gradient(bottom, rgb(62,184,229) 0%, rgb(44,160,202) 100%);
 background-image: -moz-linear-gradient(bottom, rgb(62,184,229) 0%, rgb(44,160,202) 100%);
 background-image: -webkit-linear-gradient(bottom, rgb(62,184,229) 0%, rgb(44,160,202) 100%);
 background-image: -ms-linear-gradient(bottom, rgb(62,184,229) 0%, rgb(44,160,202) 100%);
 background-image: -webkit-gradient(linear,left bottom,left top,color-stop(0, rgb(62,184,229)),color-stop(1, rgb(44,160,202)));
 -webkit-box-shadow: inset 0px 1px 0px #2ab7ec, 0px 2px 0px 0px #156785, 0px 5px 3px #999;
 -moz-box-shadow: inset 0px 1px 0px #2ab7ec, 0px 2px 0px 0px #156785, 0px 5px 3px #999;
 -o-box-shadow: inset 0px 1px 0px #2ab7ec, 0px 2px 0px 0px #156785, 0px 5px 3px #999;
 box-shadow: inset 0px 1px 0px #2ab7ec, 0px 2px 0px 0px #156785, 0px 5px 3px #999;
 }
 .a_demo_three::before {
 text-align: center;
 line-height: 20px;
 background-color:#2561b4;
 content:"1";
 width:35px;
 max-height:26px;
 height:100%;
 position:absolute;
 display:block;
 padding-top:8px;
 top:0px;
 left:-36px;
 font-size:16px;
 font-weight:bold;
 color:#8fd1ea;
 text-shadow:1px 1px 0px #07526e;
 border-right:solid 1px #07526e;
 background-image: linear-gradient(bottom, rgb(10,94,125) 0%, rgb(14,139,184) 100%);
 background-image: -o-linear-gradient(bottom, rgb(10,94,125) 0%, rgb(14,139,184) 100%);
 background-image: -moz-linear-gradient(bottom, rgb(10,94,125) 0%, rgb(14,139,184) 100%);
 background-image: -webkit-linear-gradient(bottom, rgb(10,94,125) 0%, rgb(14,139,184) 100%);
 background-image: -ms-linear-gradient(bottom, rgb(10,94,125) 0%, rgb(14,139,184) 100%);
 background-image: -webkit-gradient(linear,left bottom,left top,color-stop(0, rgb(10,94,125)),color-stop(1, rgb(14,139,184)));
 -webkit-border-top-left-radius: 5px;
 -webkit-border-bottom-left-radius: 5px;
 -moz-border-radius-topleft: 5px;
 -moz-border-radius-bottomleft: 5px;
 border-top-left-radius: 5px;
 border-bottom-left-radius: 5px;
 -webkit-box-shadow:inset 0px 1px 0px #2ab7ec, 0px 5px 0px 0px #032b3a, 0px 10px 5px #999 ;
 -moz-box-shadow:inset 0px 1px 0px #2ab7ec, 0px 5px 0px 0px #032b3a, 0px 10px 5px #999 ;
 -o-box-shadow:inset 0px 1px 0px #2ab7ec, 0px 5px 0px 0px #032b3a, 0px 10px 5px #999 ;
 box-shadow:inset 0px 1px 0px #2ab7ec, 0px 5px 0px 0px #032b3a, 0px 10px 5px #999 ;
 }
 #container_buttons{height:400px;line-height:50px;}
 #container_buttons p{margin:20px 10px;}
 .a_demo_three:active::before {
 top:-3px;
 -webkit-box-shadow:inset 0px 1px 0px #2ab7ec, 0px 5px 0px 0px #032b3a, 1px 1px 0px 0px #044a64, 2px 2px 0px 0px #044a64, 2px 5px 0px 0px #044a64, 6px 4px 2px #0b698b, 0px 10px 5px #999 ;
 -moz-box-shadow:inset 0px 1px 0px #2ab7ec, 0px 5px 0px 0px #032b3a, 1px 1px 0px 0px #044a64, 2px 2px 0px 0px #044a64, 2px 5px 0px 0px #044a64, 6px 4px 2px #0b698b, 0px 10px 5px #999 ;
 -o-box-shadow:inset 0px 1px 0px #2ab7ec, 0px 5px 0px 0px #032b3a, 1px 1px 0px 0px #044a64, 2px 2px 0px 0px #044a64, 2px 5px 0px 0px #044a64, 6px 4px 2px #0b698b, 0px 10px 5px #999 ;
 box-shadow:inset 0px 1px 0px #2ab7ec, 0px 5px 0px 0px #032b3a, 1px 1px 0px 0px #044a64, 2px 2px 0px 0px #044a64, 2px 5px 0px 0px #044a64, 6px 4px 2px #0b698b, 0px 10px 5px #999 ;
 }
 .second_button::before {content:"2";}
 .third_button::before {content:"3";}