https://www.facebook.com/events/942536724254607/?ref=newsfeed

||facebook.com$removeparam=ref

When using a vertical tab extension like Vertical Tabs Reloaded, you can hide the tab bar by adding the following line to userChrome.css:

TabsToolbar { visibility: collapse !important; }

See multi row tabs for instructions on how to find the userChrome.css file.

This mode may require changing the way new tabs open. Set browser.tabs.insertAfterCurrent and browser.tabs.insertRelatedAfterCurrent (in about:config) according to this table:

1. Open about:config and set toolkit.legacyUserProfileCustomizations.stylesheets to true.
2. Open a new tab on about:support and click the button next to “Profile Folder“
3. Go to the “chrome” directory at the profile folder, or create it if it doesn’t exist.
4. Create a file named “userChrome.css” (if it doesn’t exist) and open it in a text editor.
5. Copy the css code from below (based on multi-row_bookmarks.css)
   (copy of the css is at the bottom of this post)
6. Paste it into userChrome.css and save.
7. Restart Firefox

More firefox tweaks at firefox-csshacks

userChrome.css

/* Makes tabs to appear on multiple lines */
/* Tab reordering will not work and can't be made to work */
/* You can use multi-row_tabs_window_control_patch.css to move window controls to nav-bar*/

/* It's recommended to move tabs new-tab-button outside tabs toolbar */

/* Change the --multirow-n-rows to change maximum number of rows before the rows will start to scroll  */
/* This maximum visible rows won't work before Fx66 */
/* So this setting does nothing on Fx65 and all tab rows will be shown */
:root{
    --multirow-n-rows: 5;
    --multirow-tab-min-width: 60px;
    --multirow-tab-dynamic-width: 1; /* Change to 0 for fixed-width tabs using the above width. */
}

/* Scrollbar can't be clicked but the rows can be scrolled with mouse wheel */
/* Uncomment the next line if you want to be able to use the scrollbar with mouse clicks */

/* .tabbrowser-arrowscrollbox{ -moz-window-dragging: no-drag } */

/* Uncommenting the above makes you unable to drag the window from empty space in the tab strip but normal draggable spaces will continue to work */

#tabbrowser-tabs{
  min-height: unset !important;
  padding-inline-start: 0px !important
}
/* Selectors for Firefox 71+ */
/* These are not tabs toolbar specific but horizontal scrollbox isn't used elsewhere, except in bookmarks toolbar but there it doesn't have [part] attribute since it's not in shadow-root */
@-moz-document url(chrome://browser/content/browser.xhtml){
  .scrollbutton-up[orient="horizontal"][part]~spacer,
  .scrollbutton-up[orient="horizontal"][part],
  .scrollbutton-down[orient="horizontal"][part]{ display: none }

  scrollbox[part][orient="horizontal"]{
    display: flex;
    flex-wrap: wrap;
    overflow-y: auto;
    max-height: calc(var(--tab-min-height) * var(--multirow-n-rows));
    scrollbar-color: currentColor transparent;
    scrollbar-width: thin;
  }
}

/* Test for Firefox > 66 */
@supports (inset-block:auto){
  #tabbrowser-tabs > .tabbrowser-arrowscrollbox > .arrowscrollbox-scrollbox{
    display: flex;
    flex-wrap: wrap;
    overflow-y: auto;
    max-height: calc(var(--tab-min-height) * var(--multirow-n-rows));
    scrollbar-color: var(--toolbar-bgcolor) var(--lwt-accent-color);
    scrollbar-width: thin;
  }
  #tabbrowser-tabs > .tabbrowser-arrowscrollbox,
  #tabbrowser-arrowscrollbox{
    overflow: -moz-hidden-unscrollable;
    display: block;
  }
}

/* Test for Firefox < 66 */
@supports not (inset-block:auto){
  #tabbrowser-tabs > .tabbrowser-arrowscrollbox{
    min-height: unset !important;
  }
  #tabbrowser-tabs .scrollbox-innerbox{
    display: flex;
    flex-wrap: wrap;
  }
  #tabbrowser-tabs .arrowscrollbox-scrollbox {
    overflow: -moz-hidden-unscrollable;
    display: block;
  }
}

.tabbrowser-tab{ height: var(--tab-min-height); }
#tabbrowser-tabs .tabbrowser-tab[pinned]{
  position: static !important;
  margin-inline-start: 0px !important;
}

.tabbrowser-tab[fadein]:not([pinned]){
  min-width: var(--multirow-tab-min-width) !important;
  flex-grow: var(--multirow-tab-dynamic-width);
  /*
  Uncomment to enable full-width tabs, also makes tab dragging a tiny bit more sensible
  Don't set to none or you'll see errors in console when closing tabs
  */
  /*max-width: 100vw !important;*/
}

.tabbrowser-tab > stack{ width: 100%; height: 100% }

#scrollbutton-up,
#scrollbutton-down,
#scrollbutton-up~spacer,
#tabbrowser-tabs .scrollbutton-up,
#tabbrowser-tabs .scrollbutton-down,
#alltabs-button,
:root:not([customizing]) #TabsToolbar #new-tab-button,
#tabbrowser-tabs spacer,
.tabbrowser-tab::after{ display: none !important }

uBlock Origin – Ad-blocker
LastPass – Password Manager
Tree Style Tab – Hierarchical tab sidebar
Tab Session Manager – Session save and restore
Gesturefy – Mouse gestures
Want my RSS – RSS icon
1-Click YouTube Video Downloader – Download from YouTube
Check4Change – Monitor changes on open tabs

[OBSOLETE stopped working with firefox 71]

1. Open about:config and set toolkit.legacyUserProfileCustomizations.stylesheets to true.
2. Open a new tab on about:support
3. Click the button next to “Profile Folder”
4. Go to the “chrome” directory at the profile folder, or create it if it doesn’t exist.
5. Create a file named “userChrome.css” (if it doesn’t exist) and open it in a text editor.
6. Copy the css code from github.com/andreicristianpetcu/UserChrome-Tweaks
   (copy of the css is at the bottom of this post)
7. Paste it into userChrome.css and save.
8. Restart Firefox

userChrome.css

/* 
* Makes tabs only 22px high rather than the default 29px
* Only works on compact mode, otherwise tab height will be normal
*/

[uidensity="compact"]:root {
  --tab-min-height: 22px !important;
  --newtab-margin: -3px 0 -3px -3px !important;
}

.tabbrowser-tab {
  max-height: var(--tab-min-height) !important;
}

.tabs-newtab-button{
  margin: var(--newtab-margin) !important;
}

Decrease session store interval

Open about:config and set browser.sessionstore.interval to 1800000 (this means 30 minutes). Now, Firefox will save the session once every 30 mins instead of every 15 seconds.

Disable save to pocket icon

Open about:config and set extensions.pocket.enabled to false