Nightly 58 x64 20171028100423 de_DE @ Debian Testing layout.css.servo.chrome.enabled;true See attached screenshot.

Yeah I can reproduce this issue with today's m-c on Windows as well.

FWIW, the corresponding elements are popupset#mainPopupSet > panel#PopupAutoCompleteRichResult > xul|hbox[anonid="footer"] > xul|vbox.search-one-offs > xul|description.search-panel-one-offs > button Having a look at matching rules of this and its children, I suspect this is because of bug 1374247, because there is a rule > .searchbar-engine-one-off-item > .button-box > .button-icon { > width: 16px; > height: 16px; > } Here, .searchbar-engine-one-off-item is referring to a button, and from a search, I see the structure here is clearly xul|hbox.button-box > children > xul|image.button-icon [1] So this rule doesn't take effect because we cannot match the <xul:image> here. [1] https://searchfox.org/mozilla-central/rev/1ebd2eff44617df3b82eea7d2f3ca1b60cc591a0/toolkit/content/widgets/button.xml#218-235

Oh, and apparently this is one rule which emilio has fixed in his try push in bug 1374247 comment 21.

P1 because this icon bug will block us from enabling stylo-chrome. It's not a serious bug, but every Nightly user will see it and people might file duplicate bug reports.

Probably known already, the problem also exists on the Search Box.

Verified fixed in Nightly 58 x64 20171104100412 de_DE @ Debian Testing (KDE, Radeon RX480). Thank you! (Please decide whether this bug is FIXED or a DUPLICATE.)