If you scroll down the page, the word "IMMUTABLE" overlaps with the page's text.
Disabling Webrender fixes the problem.
I am using latest Nightly on Ubuntu 18.04 with Intel driver.
Was fixed by https://github.com/servo/webrender/pull/3315.
I'll land a test for this in Gecko.
Most helpful comment
Bugzilla: bug 1495791
Screencast
Regression range: https://github.com/servo/webrender/compare/3829687ffbe8d55885d71a3d5e5e79216251548f...8e697f8cb1f1aab2e5f6b9b903eb7191340b10c5