Created attachment 320392 [details] Screenshot comparing rendering of Lucida Grande bold in WebKit and Blink Steps to reproduce: 1. Install Lucida Grande font. 2. Open a web page that uses it, for instance: https://developer.apple.com/library/content/documentation/QuickTime/QTFF/QTFFChap2/qtff2.html I've attached an screenshot showing the problem. The first line of text has been modified with the inspector to use regular (non-bold) Lucida Grande, for comparison.
It also happens with Tahoma.
For some reason, the interpretation of font-weight for some fonts (including both Lucida Grande and Tahoma) is inconsistent among browsers. This MDN page includes a handy tester: https://developer.mozilla.org/en-US/docs/Web/CSS/font-weight The case of WebKitGTK is surprising and problematic. It actually knows how to render the font with the correct bold thickness and does that when requested font-weight: 600... but in CSS `bold` stands for 700. When requested 700 and up it artificially thickens the font.
Created attachment 320393 [details] Comparison of font-weight among browsers
Can you attach a .webarchive of the page? File -> Save As... -> Format: Web Archive I can't reproduce this on my machine, so maybe the page is different for you.
Created attachment 320537 [details] Page showing the issue (webarchive)
Created attachment 320538 [details] Page showing the issue (mhtml)
Oh, I didn't realize this bug only occurs in GTK. I don't think I can help.