User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0 Steps to reproduce: Firefox 65, 64-bit, Windows 10 In Firefox, go to Menu -> Customize -> Themes Select the Light theme. Actual results: The title bar (tab bar) color now matches the Windows 10 accent color, which for me is DARK GREY. The Light theme now seems to be identical to the Default theme. (Changing my Windows accent color to something else, e.g. RED, also changes the Firefox title/tab bar color to RED in both Light and Default themes) Expected results: When using the Light theme, the Firefox tab/title bar should always be light grey. It should ignore the Windows accent color. I assume this is a bug because, if intentional, then the Light theme is now pointless (indistinguishable from Default). I didn't pin it to a specific build, but the range is fairly narrow. 11/01 Nightly (20181101151140) is correct 11/03 Nightly (20181103220126) is broken

hi, i think this was an intentional change in bug 1503022.

You can configure Windows 10 not to use the accent color in the title bar, and the Light theme will honor that.

But the point of the Light theme is to be Light. I don't want to change Windows 10 to not use the accent color in the title bar (system-wide). For most apps this is a helpful visual indicator of the selected window. But that's because for most applications, the title bar is just a thing to drag the window around with. Windows applications that integrate part of their functionality into the title bar (examples: Visual Studio, Excel, Outlook) DO NOT use the Windows 10 accent color when focused. Firefox falls into this category (integrates functionality, specifically the tab bar) into the title bar and therefore it should NOT use the accent color when the window is focused. I feel Firefox should use the established convention of the platform.