Yeah, plus, the fact that you fix something is the "why" part of your commit message, it should go in the body. The result could look like this :
> Reduce overlaying div element width
>
> This caused a bug on some devices : the div would overlay the close button, causing it to be unreachable.
I think that commit message that begin with "fix" are often not very good. Basically, you're saying "It was broken, this commit fixes it", not what was broken nor how your commit is supposed to fix it (yeah because sometimes, people think they are fixing something and actually create another bug in another part of the thing).
Imperative style normally produces more direct messages than that; talk about how it behaves now, not how it used to:
"Close window when button clicked"
Or, assuming "button" here means "close button":
"Close window when user clicks close button"