STR: 1. In Windows, activate a High Contrast system theme. 2. View some ogg video directly in the browser -- e.g.: http://download.blender.org/peach/bigbuckbunny_movies/big_buck_bunny_720p_stereo.ogg 3. Try to use the video controls. ACTUAL RESULTS (in current Nightly): Video controls aren't visible -- just the "0:34/9:56" time in the control bar is visible. The controls *are there*, though -- i can trigger them by clicking the blank space where I expect them to be (e.g. play/pause at far left, scrubber to the right of that). They're just not visible (and it's not obvious where to click to find them). EXPECTED RESULTS: Video controls should be visible, or at least easier to find. In current Firefox release (51.0.1), it's not perfect -- the video controls' *icons* aren't visible -- but they do have visible outlines & hence obvious click targets. And the scrubber's time-label is also visible & hence is an obvious click target for the scrubber.

Here's a screenshot of the Firefox 51 rendering, with the helpful outlines (borders?) around buttons. The leftmost yellow box is play/pause. The "0:04" next to that is the scrubber label. And the yellow boxes on the right side are mute and fullscreen.

Note: I don't know a lot about high contrast mode, but basically it seems like we suppress lots of colors/graphics & draw borders & outlines & text **using the high-contrast-theme's foreground color**. So we may be able to restore Firefox-51-like behavior if we add a transparent outline around each of the buttons in our refreshed video UI. And since "outline" doesn't take up space, this new styling should be imperceptible for users with normal (non-high-contrast) themes. For demonstration purposes, here's a sample jsfiddle with a transparent outline that gets rendered (as yellow, the same color as the text) in the Windows "High Contrast #1" theme: https://jsfiddle.net/2m2aLs9t/

Oops. Now that I'm triaging my needinfo requests, I see that this is a dupe of a bug I'm already needinfo'd on :D (bug 1022553) (Technically bug 1022553 was filed on the original boxes-only UI being unusable, but it's been expanded to cover the worse issue in current Nightlies, too, and it sounds like we can get things to an entirely better state perhaps.)