input fields can be styled as you wish. So instead of zoom, you could have
input[type="checkbox"]{
width: 30px; /*Desired width*/
height: 30px; /*Desired height*/
}
EDIT:
You would have to add extra rules like this:
input[type="checkbox"]{
width: 30px; /*Desired width*/
height: 30px; /*Desired height*/
cursor: pointer;
-webkit-appearance: none;
appearance: none;
}
Check this fiddle http://jsfiddle.net/p36tqqyq/1/