One quick solution to resizing the radio button is to transform it:
input[type='radio'] {
transform: scale(2);
}
This results in all radio buttons being twice as large. As always, check browser support.
Original Answer (May 27, 2012)
You cannot change the size of the radio button. Typically people will design a custom UI element to replace the UI aspect of the checkbox/radiobutton. Clicking it results in a click on the underlying checkbox/radio button.
See an example here: http://webdesign.maratz.com...radio-buttons/jquery.html
