You can change the color of the check box using css or jquery. I want to change only the color border of the checkbox.
if you want to do this with pure css, you will not get a result that will work in all browsers. if you are using jqueryUI there are some checkbox options like this or this . otherwise you will have to do something similar yourself using images.
Editing:note: today (March 2015) this post is about 5 years old - then IE6 still had a market share of about 10% and even the latest IE (version 8 at that time) was crappy as hell. This answer is technically outdated today .
Flags are marked because they have different styles for each browser that displays them. As Nick Craver commented, images are the only reliable way to safely select checkboxes.