Re: [csswg-drafts] [css-tables-3] How table borders should be painted at the corner? (border-collapse: collapse) (#13406)

Right. I'm inclined to say Firefox's "clean mitres" is right here because this matches how borders generally work in non-table painting. 

(FWIW [Firefox's draw code for borders](https://searchfox.org/firefox-main/source/layout/painting/nsCSSRendering.cpp#3276-3341), [Chrome's code for collapsed borders](https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/core/paint/table_painters.cc;l=518-730?q=table_painters.cc), [Webkit's code for collapsed borders](https://github.com/WebKit/WebKit/blob/5f682140ae0d0d494c57494fa5cbc6908453417b/Source/WebCore/rendering/RenderTableCell.cpp#L1425-L1492)).

Of note WebKit has a comment:

> We never paint diagonals at the joins.  We simply let the border with the highest precedence paint on top of borders with lower precedence.  

I don't know the history here, but I'd wager Chrome's lineage to WebKit is why the two behave the same.

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Received on Thursday, 29 January 2026 12:17:45 UTC