widthattribute does the job (as expected). However, for some strange reasons it is completely ignored by FF.
To change the width of FileUpload control in FF you have to use
sizeattribute instead. Example:
<asp:FileUpload ... size="50" />The units used by
sizeattribute are characters. Remember to use both
size(for FF) and
width(for all other browsers) to make the change visible for all users. Sometimes it may be tricky to make this field have the same width on all browsers.
I'm not sure why Mozilla did it this way but I don't like it at all. Any Ideas?
I found solution here.