How do I change scrollbar colors for "responsive mode"

[s0me0ne]

When I go into Responsive Design Mode, the scrollbars are way too light and transparent. I do a lot of testing of websites and this is slowing me down as I need to see a lot right away when the scrollbars appear.

Is there a way to change the opacity and color of them?

I tried using an extension /addon
https://addons.mozilla.org/firefox/addo ... crollbars/
But that plugin also adds extra width that messes with the responsive layout, its not much but it does cause some issues where I see a scrollbar and others dont at times, so the developers usually argue back on me that they dont see a horizontal scrollbar and I do because the vertical scrollbar in that plugin is pushing stuff.

So Ideally I would like to fix this in Firefox and not use a extension.

Thanks

[morat]

Try the stylish extension.

Search
http://userstyles.org/styles/browse?sea ... =scrollbar

Example
http://userstyles.org/styles/68038