Radios kannst du im Firefox nur relativ eingeschränkt vergrößern.
Beispiel-CSS:
input[type="radio"] {
-moz-appearance: none!important;
width: 2em!important;
height: 2em!important;
margin: 0 !important;
padding: 0 !important;
-moz-border-top-colors:transparent;
-moz-border-left-colors:transparent;
-moz-border-right-colors:transparent;
-moz-border-bottom-colors:transparent;
-moz-outline:2px solid #0033EE;
-moz-outline-radius:100%;
}
*|*::-moz-radio {
width: 0.8em;
height: 0.8em;
-moz-border-radius: 0.4em;
color:green !important;
}