Problem with Firefox browser on NetBSD

[Dmitrii Postolov <dpostolov%yandex.ru@localhost>]

Hi to all! Sorry for my bad English...

aspire9$ uname -a

NetBSD aspire9.localnet 9.3_STABLE NetBSD 9.3_STABLE (GENERIC) #0: Sun 
Sep  4 12:09:57 +05 2022 
root@aspire9.localnet:/root/sysbuild/amd64/obj/usr/src/sys/arch/amd64/compile/GENERIC 
amd64

Hardware: Acer Aspire XC-895 CPU Intel i5-10400, Intel HD Graphics 630 
(wsfb driver, on NetBSD 9.99 new drm don't work correctly)

On NetBSD some problem with Firefox-[ESR]. On FreeBSD (drm and scfb) all 
OK with Firefox.

On NetBSD and Firefox: window frames are not displayed correctly on some 
sites and some pictures are not visible.

NetBSD-Screenshot-Yandex.ru: https://disk.yandex.ru/i/DZImWz8GwL2FDA
FreeBSD-Screenshot-Yandex.ru: https://disk.yandex.ru/i/FhCBob1orPo5MQ

NetBSD-Screenshot-VK.com: https://disk.yandex.ru/i/fDI-LFj7jW4_Xg
FreeBSD-Screenshot-VK.com: https://disk.yandex.ru/i/iw5sfen78nubDQ

P.S. In some sites on NetBSD use Firefox without change of the User 
Agent is impossible, some sites don't know about NetBSD specs and try to 
display mobile version of site.