Ajax Loader
HTML 
<div id="button">
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<div id="button">
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  <a class="butt">PUSH</a>
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</div>
 
CSS 
body {
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body {
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  background: #ddd;
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}
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#button {
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  width: 100px;
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  height: 100px;
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  border-bottom: 2px solid #eee;
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  background-image: -webkit-linear-gradient(top, #999, #d0d0d0 80% );
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  background-image: -moz-linear-gradient(top, #999, #d0d0d0 80% );
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  background-image: -ms-linear-gradient(top, #999, #d0d0d0 80% );
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  background-image: -o-linear-gradient(top, #999, #d0d0d0 80% );
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  background-image: linear-gradient(top, #999, #d0d0d0 80% );
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  -moz-border-radius: 100px;
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  -webkit-border-radius: 100px;
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  border-radius: 100px;
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  box-shadow: inset rgba(0,0,0,0.2) 0px 5px 6px ;
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  left: 50%;
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  top: 50%;
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  margin-left: -50px;
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  margin-top: -50px;
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  position: absolute;
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}
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.butt {
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  position: absolute;
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  width: 80px;
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  height: 52px;
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  left: 10px;
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  top: 10px;
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  cursor: pointer;
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  font-family: "Lucida Sans";
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  font-weight: bold;
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  font-size: 23px;
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  color: #888;
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  text-shadow: 0px 1px 0px #fff;
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  text-align: center;
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  padding-top: 28px;
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  -moz-border-radius: 100px;
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  -webkit-border-radius: 100px;
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  border-radius: 100px;
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  background-image: -webkit-linear-gradient(top, #eee, #bbb 70%, #9f9f9f 100% );
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  background-image: -moz-linear-gradient(top, #eee, #bbb 70%, #9f9f9f 100% );
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  background-image: -ms-linear-gradient(top, #eee, #bbb 70%, #9f9f9f 100% );
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  background-image: -o-linear-gradient(top, #eee, #bbb 70%, #9f9f9f 100% );
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  background-image: linear-gradient(top, #eee, #bbb 70%, #9f9f9f 100% );
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  background-position: 0 6px;
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  background-color: #eee;
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  background-repeat: no-repeat;
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  -webkit-box-shadow: rgba(0,0,0,.4) 0 3px 6px;
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  -moz-box-shadow: rgba(0,0,0,.4) 0 3px 6px;
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  box-shadow: rgba(0,0,0,.4) 0 3px 6px;
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  -webkit-transition: all .1s ease-in;
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  -moz-transition: all .1s ease-in;
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  -ms-transition: all .1s ease-in;
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  -o-transition: all .1s ease-in;
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  transition: all .1s ease-in;
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}
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.butt:hover {
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  background-position: 0 0px;
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  -webkit-box-shadow: rgba(0,0,0,.4) 0 3px 8px;
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  -moz-box-shadow: rgba(0,0,0,.4) 0 3px 8px;
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  box-shadow: rgba(0,0,0,.4) 0 3px 8px;
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}
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.butt:active {
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  width: 76px;
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  height: 48px;
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  margin: 2px 0 0 2px;  
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  border-bottom: 1px solid #fff;
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  font-size: 21px;
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  color: #777;
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  -webkit-box-shadow: inset rgba(0,0,0,.5) 0px 5px 10px;
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  -moz-box-shadow: inset rgba(0,0,0,.5) 0px 5px 10px;
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  box-shadow: inset rgba(0,0,0,.5) 0px 5px 10px;
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}
 

Animated Push Button

CSSDeck G+