css set width by right code example
Example: increase width from right to left css
<div class="icon">
test
</div>
<style>
.icon{
width: 128px;
height: 128px;
background: url(icons.png) no-repeat red;
background-position: left top;
-webkit-transition: width .2s;
position:absolute;
top:0; right:0;
}
.icon:hover{
width:250px
}
</style>