Firefox

1. In about:config enable toolkit.legacyUserProfileCustomizations.stylesheets
2. Copy 'chrome' folder in 'Profile Folder' (Menu > Help > Troubleshooting Information > Profile Folder)
3. Restart Firefox

• Use "System theme - auto"
• Drag Bookmarks Toolbar Items to the left of the address bar
• To set the wallpaper in a new tab, place a .jpg or .png image in the Chrome folder and rename it to "bg". Restart Firefox

Sidebery

1. Install Sidebery
2. Copy the code from Sidebery-Sidebar.css to Sidebery / Settings / Styles editor / Sidebar
3. Copy the code from Sidebery-GroupPage.css to Sidebery / Settings / Styles editor / Group page

YouTube

1. Install Stylus
2. Open YouTube
3. In Stylus, click New Style ...
4. In the window that opens, click Import
5. Copy the code here from the Stylus-YouTube.css file and click replace style
6. Save

• To open the header, move the cursor to the top edge, but not all the way

about:config

• Opening a bookmark in a new tab browser.tabs.loadBookmarksInTabs true
• Smoothness of scrolling general.smoothScroll.mouseWheel.durationMaxMS 380
• Disable add-on recommendations extensions.htmlaboutaddons.recommendations.enabled false
• Do not open download panel browser.download.alwaysOpenPanel false
• Restore pinned tabs on demand browser.sessionstore.restore_pinned_tabs_on_demand true
• OS text scaling settings should only affect text scaling browser.display.os-zoom-behavior 2
• Trim https browser.urlbar.trimHttps true