Created attachment 8869840 [details] testcase.htm Lead attached testcase. You will see a blank page but there should be a heart emoji. Works on Chrome and Edge. This problem affects github, the heart reaction to comments is not visible.
The character sequence is: ❤ U+2764 HEAVY BLACK HEART ️ U+FE0F VARIATION SELECTOR-16 It works for me. If you go to the fonts panel in devtools, what fonts does it say are used?
Summary: My heart is broken → heart emoji doesn't show up
It says "Segoe UI Emoji" and "Times New Roman". Note that the emoji is shown if I add surrounding text, then heart overlaps the text. It seems that when there is no text, the heart ends up totally clipped.
Created attachment 8869865 [details] screenshot.png This is a comparison between U+2764 U+FE0E and U+2764 U+FE0F when they are alone, preceded, followed or surrounded by dots.
For me, the red heart shows up as expected (in both FF53 and Nightly 55), but it has zero advance width (and so it will overlap surrounding text). But that appears to be a font problem rather than a Firefox bug; the same happens in MS Edge.
If it's a bug in the font that comes with Windows, it might be worth working around until that's fixed. Even if that involves falling back to the built in emoji font.
Priority: -- → P3
This is fixed in Windows 10 1709, but the problem remains for Windows 10 1703.
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