Supposedly the gradient below is expensive and I never liked using a gradient for the solid background in the first place. According to the CSS 3 Background and Borders spec for background-color[1], "The background color is clipped according to the ‘background-clip’ value associated with the bottom-most background image." We can use this to avoid the gradient. %define fgTabBackgroundMiddle linear-gradient(transparent 0px, transparent 2px, -moz-dialog 2px, -moz-dialog) Compare talos on the WIP for Windows-only didn't show much change. Perhaps it will help non-Windows or there was a bug in the WIP. compare-talos on v.1: http://compare-talos.mattn.ca/?oldRevs=631237eca83a&newRev=44a12140e649&submit=true [1] http://www.w3.org/TR/css3-background/#the-background-color

Hrm. Yeah, I was expecting more of a win here. For reference, here's the original try push that tested this: https://tbpl.mozilla.org/?tree=Try&rev=71846875686c And, specifically, here's the patch: https://hg.mozilla.org/try/rev/71846875686c Looking at my Try push, it looks like I applied that patch not on tip, but on the patch that first landed those curvy tabs. :/ So that at least explains the discrepancy.

Comment on attachment 803510 [details] [diff] [review] v.1 Use padding with background-clip:content-box Review of attachment 803510 [details] [diff] [review]: ----------------------------------------------------------------- Cancelling review request until I find out about the TODO. ::: browser/themes/shared/tabs.inc.css @@ +178,5 @@ > background-repeat: no-repeat; > } > > .tab-background-middle[selected=true] { > + background-clip: padding-box, padding-box, content-box; /* TODO check for other overrides to update clip there */ So how about this TODO? @@ +187,3 @@ > background-repeat: repeat-x; > background-size: auto 100%; > + /* The padding-top combined with background-clip: content-box (the bottom-most) ensure the background-color doesn't extend above the top border. */ Nit - please put this comment on two lines. @@ +191,5 @@ > } > > /* Selected tab lightweight theme styles */ > .tab-background-middle[selected=true]:-moz-lwtheme { > + background-color: transparent; Should this be @fgTabBackgroundColor@?

(In reply to Mike Conley (:mconley) from comment #2) > Comment on attachment 803510 [details] [diff] [review] > v.1 Use padding with background-clip:content-box > > Cancelling review request until I find out about the TODO. > > ::: browser/themes/shared/tabs.inc.css > @@ +178,5 @@ > > background-repeat: no-repeat; > > } > > > > .tab-background-middle[selected=true] { > > + background-clip: padding-box, padding-box, content-box; /* TODO check for other overrides to update clip there */ > > So how about this TODO? Oops, I already checked this on all platforms. > > @@ +187,3 @@ > > background-repeat: repeat-x; > > background-size: auto 100%; > > + /* The padding-top combined with background-clip: content-box (the bottom-most) ensure the background-color doesn't extend above the top border. */ > > Nit - please put this comment on two lines. ok > @@ +191,5 @@ > > } > > > > /* Selected tab lightweight theme styles */ > > .tab-background-middle[selected=true]:-moz-lwtheme { > > + background-color: transparent; > > Should this be @fgTabBackgroundColor@? No, since this is for LWT. I don't think it will be visible unless the LWT has transparency. This is the same value as prior to the patch.

Comment on attachment 803510 [details] [diff] [review] v.1 Use padding with background-clip:content-box Review of attachment 803510 [details] [diff] [review]: ----------------------------------------------------------------- Just chop out the TODO and split that comment over two lines, and you're good to land. Thanks Matt!

Thanks! https://hg.mozilla.org/projects/ux/rev/14a05f3555df