I've met that bug in website, where should I tell about it?

General Meta
1

Header in website is turned from it's appropriate place, where I scroll down.
I've fixed it by turning off that “!important” rule.
Where should I tell about that bug?

as it, with “!important”
as it, with “!important”1920×1200 288 KB

fixed, without “!important”
fixed, without “!important”1920×1200 288 KB

2

My system is:
Ubuntu 24.04
Google Chrome: “Version 148.0.7778.178 (Official Build) (64-bit)” from official .deb