Usually a submit button in a form is an
input element of type “submit” so probably you have set the width of all input fields in general in the CSS somewhere which, of course, will also set the width of the submit button (and the CSS is overriding HTML attributes like
size etc.).
You can reset that width by setting it specifically for that button with a CSS 2.1 selector (which won’t work in IE 6, though):
Code:
input[type=submit] {width: auto;}
Or, to get a cross-browser compatible solution give your sumit input (or a parent) an ID and address it with the ID selector in the CSS.