+++ This bug was initially created as a clone of Bug #1198236 +++

Comment on attachment 8787971 [details] [diff] [review] patch Review of attachment 8787971 [details] [diff] [review]: ----------------------------------------------------------------- What's the perf impact of using border-image and would it be helpful to only use this method for the pinned tabs, if that's the only case where it's necessary? ::: browser/themes/shared/tabs.inc.css @@ +446,3 @@ > margin-inline-start: -1px; > + border-left: 1px solid; > + border-image: linear-gradient(transparent 6px, Why are these offsets at the top/bottom 1 pixel greater than with the margin-top/bottom?

(In reply to :Gijs Kruitbosch from comment #2) > What's the perf impact of using border-image and would it be helpful to only > use this method for the pinned tabs, if that's the only case where it's > necessary? I suppose we'll see when landing the patch... If the difference is too small for a regression to be noticed on talos then I think we shouldn't worry about it. > ::: browser/themes/shared/tabs.inc.css > @@ +446,3 @@ > > margin-inline-start: -1px; > > + border-left: 1px solid; > > + border-image: linear-gradient(transparent 6px, > > Why are these offsets at the top/bottom 1 pixel greater than with the > margin-top/bottom? It was needed to get the same visual result. I have no idea why.

Comment on attachment 8787971 [details] [diff] [review] patch Alright, let's see if this helps.

Pushed by dgottwald@mozilla.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/038c1f5864ef Make positioned pinned tab separators not touch the toolbar. r=gijs

I've managed to reproduced this bug in Firefox Nightly 51.0a1 (2016-09-04) ; (Build ID: 20160904030201) from Ubuntu 14.04.5 (64 Bit) This Bug is now verified as fixed on Latest Firefox Developer Edition 51.0a2 (2016-11-13) (64-bit) Build ID: 20161113004006 User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:51.0) Gecko/20100101 Firefox/51.0 OS: Linux 4.4.0-47-generic; Ubuntu 14.04.5