本实例主要应用gradient，然后使用box-shadow和border-raidus生成一个看起来很酷的按钮。然后download文字和版本文字分为两层，download文字层的z-index大于版本文字的z-index，鼠标滑过的时候改变download文字的宽度，露出下面的版本文字层。
css主要代码：
#btn-wrap {
position:relative;
padding:5px;
margin:0 auto;
width:230px;
height:50px;
display:block;
text-decoration:none;
margin-bottom:30px;
background: #242428;
background: -webkit-gradient(linear, 0 bottom, 0 top, from(#2d2d30 ), to(#17171a));
background: -moz-linear-gradient(-90deg, #17171a, #2d2d30 );
-webkit-border-radius: 50px;
-moz-border-radius: 50px;
border-radius: 50px;
-webkit-box-shadow: 0 1px 0 #37373b;
-moz-box-shadow: 0 1px 0 #37373b;
box-shadow: 0 1px 0 #37373b;
}
span.title{
color:#d6d6e7;
font:30px/58px "BebasNeueRegular", Helvetica, Arial, sans-serif;
height:50px;
width:230px;
display:block;
position:relative;
-webkit-box-shadow: 0 -1px 0 #8d8d94, 0 1px 1px #0b0b0c;
-moz-box-shadow: 0 -1px 0 #8d8d94, 0 1px 1px #0b0b0c;
box-shadow: 0 -1px 0 #8d8d94, 0 1px 1px #0b0b0c;
background: #52525c;
background: -webkit-gradient(linear, 0 bottom, 0 top, from(#383840 ), to(#5a5a64));
background: -moz-linear-gradient(-90deg, #5a5a64, #383840 );
-webkit-border-radius: 50px;
-moz-border-radius: 50px;
border-radius: 50px;
z-index:5;
-webkit-transition:width .2s ease-out;
-moz-transition:width .2s ease-out;
-o-transition:width .2s ease-out;
}
#btn-wrap:hover span.title {
font-size:19px;
width:135px;
}
#info {
position:absolute;
height:50px;
width:230px;
top:5px;
right:4px;
-webkit-box-shadow: 0 -1px 0 #404042, 0 1px 1px #0b0b0c;
-moz-box-shadow: 0 -1px 0 #404042, 0 1px 1px #0b0b0c;
box-shadow: 0 -1px 0 #404042, 0 1px 1px #0b0b0c;
background: #2a2a2d;
background: -webkit-gradient(linear, 0 bottom, 0 top, from(#212124 ), to(#2a2a2d));
background: -moz-linear-gradient(-90deg, #2a2a2d, #212124 );
-webkit-border-radius: 50px;
-moz-border-radius: 50px;
border-radius: 50px;
z-index:4;
}
#info p {
width:65px;
margin:12px 17px 0 0;
position:absolute;
right:0;
color:#7c7c84;
font:11px/12px Helvetica, Arial, sans-serif;
text-align:left;
}
.boxtuffs {
color: #7c7c84;
font:12px Helvetica, Arial, sans-serif;
text-shadow: 0 -1px 0 #000;
text-decoration:none;
-webkit-transition:all .2s ease-out;
-moz-transition:all .2s ease-out;
-o-transition:all .2s ease-out;
}
.boxtuffs:hover {
color: #27896a;
}