Have a look at this article which shows the differences between browsers where form controls are concerned.
Chances are that if you are applying a style correctly and it is not showing then that browser does not allow you to change that property on a form control.
As others have said it's best to leave form controls alone especially check boxes, radio buttons and selects. Other form elements such as text boxes, textareas and submits can be styled a bit better but there are still limits between browsers.
A lot of the styling of form controls is done by the browser and can't be easily over-ridden.