Size of checkbox, buttons, in forms



Does anyone know how to change the size of the checkbox in a form? And the size of the check inside it? Here is the page that I am working on. It seems to work just fine. But I want to make the checkbox bigger so that people with low vision can find it, and check it off, easier. Same thing with the submit button -- bigger button, bigger text. Also, I might like to change the character for the check -- perhaps completely color the box, or use a large, bold X instead of a checkmark.
Alright, I figured out how to make the submit button bigger. But I decided to eliminate the checkbox altogether, as I just couldn't figure out how to make it display bigger -- except in MSIE. There i used some css code that worked in msie but didn't work in Firefox and Opera.