Can confirm issue using Fedora 29 and Firefox 65
Graphics: Device-1: Intel HD Graphics 630 driver: i915 v: kernel Display: x11 server: Fedora Project X.org 1.20.3 driver: i915 resolution: 1368x768~60Hz, 1920x1080~60Hz OpenGL: renderer: Mesa DRI Intel HD Graphics 630 (Kaby Lake GT2) v: 4.5 Mesa 18.2.8
Can confirm issue using Fedora 29 and Firefox 65
Graphics:
Device-1: Intel HD Graphics 630 driver: i915 v: kernel
Display: x11 server: Fedora Project X.org 1.20.3 driver: i915 resolution: 1368x768~60Hz, 1920x1080~60Hz
OpenGL: renderer: Mesa DRI Intel HD Graphics 630 (Kaby Lake GT2) v: 4.5 Mesa 18.2.8