cookies => PREF => f1=50000000&f6=43418
copy: &f6=43418 or &f6=8
*after cleaning cookies new layout comes back, if you want to keep it do not delete cookies.
(F12 / ctrl+shift+i / ctrl+shift+c) - or right click anywhere and INSPECT
YT THEME: https://userstyles.org/styles/123887/youtube-better-full-dark-theme-2018-arc
