User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko/20100101 Firefox/61.0 Build ID: 20180408220126 Steps to reproduce: Navigating to https://blog.travis-ci.com/2018-04-03-incident-post-mortem with WebRender enabled. Actual results: See attached gifv, the font weight seems to have gotten heavier as I scrolled down the page. Expected results: The font weight should have stayed the same.

It'd be good to know what this is

Can you still reproduce this?

(In reply to Jeff Muizelaar [:jrmuizel] from comment #2) > Can you still reproduce this? Yes, I can still repro this.

I can also reproduce this. It *mostly* looks like we're just dropping to greyscale, suggesting a fallback. However I see hints of colour as if subpixel was *kinda* still there? Might just be an artifact from how I'm zooming in windows though.

At least for me, only reproduces with subpixel AA enabled, but not with it disabled. I tried running mozregression on this, and it claims bug 1339474, which turned on APZ for WR, is where this might have started. Kats, ideas?

Sorry, I have no idea why turning on APZ would affect this. I can repro the behaviour on macOS with default WR-enabled settings as well as with layers.async-pan-zoom.enabled set to false. So I don't know if this is really specific to APZ or if that's just a red herring.

This should be addressed by WR PR https://github.com/servo/webrender/pull/2693