[CentOS] Buttons too big in Firefox for Linux

[Gary Stainburn]

On Wednesday 01 February 2017 14:49:16 Alice Wonder wrote:
> On 02/01/2017 06:44 AM, Jonathan Billings wrote:
> >
> > Any chance your browser is zoomed in?  Or maybe you've told firefox
> > that your DPI is higher than it should be? (layout.css.devPixelsPerPx)
>
> That's a good possibility, FireFox has an annoying habit of zooming if
> the ctrl button gets stuck even temporarily, and it isn't always obvious
> it has happened.

I didn't make any changes to anything, other than run the 'yum update'.

I did read that round about version 30 Firefox started respecting the DPI, but 
that was years ago.

layout.css.devPixelsPerPx  is currently set to 

default	string	-1.0

Is this correct?

Firefox isn't zoomed in.  If I do zoom in/out using <CTRL>+ or <ctrl>- then 
everything resizes together, and the buttons are still proportionally 
oversezed.

I've currently got Firefox 50.1.0 and FirefoxDeveloperEdition 53.0a2 and they 
both exhibit the same problem.