<!DOCTYPE html>
<html>
<head>
<style type="text/css">
.hideradios input {
display: none;
}
input:checked + label {
background-color: yellow;
}
</style>
<script type="text/javascript">
function chooseSecondItems()
{
document.getElementById("a2").checked = true;
document.getElementById("b2").checked = true;
}
</script>
</head>
<body onload="chooseSecondItems();">
<div>
<div><input type="radio" name="a" id="a1"><label for="a1">radio #a1</label></div>
<div><input type="radio" name="a" id="a2"><label for="a2">radio #a2</label></div>
<div><input type="radio" name="a" id="a3"><label for="a3">radio #a3</label></div>
<div><input type="radio" name="a" id="a4" checked><label for="a4">radio #a4</label></div>
<div><input type="radio" name="a" id="a5"><label for="a5">radio #a5</label></div>
</div>
<div class="hideradios">
<div><input type="radio" name="b" id="b1"><label for="b1">radio #b1</label></div>
<div><input type="radio" name="b" id="b2"><label for="b2">radio #b2</label></div>
<div><input type="radio" name="b" id="b3"><label for="b3">radio #b3</label></div>
<div><input type="radio" name="b" id="b4" checked><label for="b4">radio #b4</label></div>
<div><input type="radio" name="b" id="b5"><label for="b5">radio #b5</label></div>
</div>
</body>
</html>