The bi-directional animation is done by using ~ sibling selectors. ps. WebKit only -> uses appearance:none; Cross-Browser version by @ryanseddon: http://jsfiddle.net/ryanseddon/FeJT2/

index.html

<input type="radio" name="name" checked />
<input type="radio" name="name" />
<input type="radio" name="name" />
<input type="radio" name="name" />
<input type="radio" name="name" />

script.js

// Radio Inputs with bi-directional animation
// by simurai

// ps. WebKit only -> uses appearance:none;
// Cross-Browser version by @ryanseddon: http://jsfiddle.net/ryanseddon/FeJT2/

style.css

body {
  padding: 50px;
  background-color: hsl(0,0%,20%);
}


input {
	-webkit-appearance: none; /* remove default */
	display: block;
	margin: 10px;
	width: 24px;
	height: 24px;
	border-radius: 12px;
	cursor: pointer;
	vertical-align: middle;	
	box-shadow: hsla(0,0%,100%,.15) 0 1px 1px, inset hsla(0,0%,0%,.5) 0 0 0 1px;		
	background-color: hsla(0,0%,0%,.2);
	background-image: -webkit-radial-gradient( hsla(200,100%,90%,1) 0%, hsla(200,100%,70%,1) 15%, hsla(200,100%,60%,.3) 28%, hsla(200,100%,30%,0) 70% );
	background-repeat: no-repeat;	
	-webkit-transition: background-position .15s cubic-bezier(.8, 0, 1, 1),
						  -webkit-transform .25s cubic-bezier(.8, 0, 1, 1);
}
input:checked {
	-webkit-transition: background-position .2s .15s cubic-bezier(0, 0, .2, 1),
						  -webkit-transform .25s cubic-bezier(0, 0, .2, 1);
}
input:active {
	-webkit-transform: scale(1.5);
	-webkit-transition: -webkit-transform .1s cubic-bezier(0, 0, .2, 1);
}



/* The up/down direction logic */

input,
input:active {
    background-position: 0 24px;
}
input:checked {
    background-position: 0 0;
}
input:checked ~ input,
input:checked ~ input:active {
    background-position: 0 -24px;
}