Perhaps someone a lot smarter than myself can explain it to me, but I’ve never understood why browsers, by default, do not show form input submit buttons as clickable by changing your mouse cursor to a pointer (hand pointing finger) when hovering over them?
I think the cursor should change to a pointer whenever an area is actionable upon clicking.
Example of the difference between the default arrow (first hash) and pointer (second hash):
Hover over each with your mouse cursor.
# | #
To correct this, simply drop the following CSS in all your stylesheets:
input[type="submit"]{cursor:pointer}