pseudo-fullscreen-firefox
                                
                                
                                
                                    pseudo-fullscreen-firefox copied to clipboard
                            
                            
                            
                        Hides and improves Firefox and YouTube UI, giving maximum space for content and aiding concentration

Firefox
- In about:config enable 
toolkit.legacyUserProfileCustomizations.stylesheets - Copy 'chrome' folder in 'Profile Folder' (Menu > Help > Troubleshooting Information > Profile Folder)
 - 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
- Install Sidebery
 - Copy the code from Sidebery-Sidebar.css to Sidebery / Settings / Styles editor / Sidebar
 - Copy the code from Sidebery-GroupPage.css to Sidebery / Settings / Styles editor / Group page
 
YouTube
- Install Stylus
 - Open YouTube
 - In Stylus, click New Style ...
 - In the window that opens, click Import
 - Copy the code here from the Stylus-YouTube.css file and click replace style
 - 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.loadBookmarksInTabstrue - Smoothness of scrolling
general.smoothScroll.mouseWheel.durationMaxMS380 - Disable add-on recommendations
extensions.htmlaboutaddons.recommendations.enabledfalse - Do not open download panel
browser.download.alwaysOpenPanelfalse - Restore pinned tabs on demand
browser.sessionstore.restore_pinned_tabs_on_demandtrue - OS text scaling settings should only affect text scaling
browser.display.os-zoom-behavior2 - Trim https
browser.urlbar.trimHttpstrue