User stylesheet to bring back the old titlebars in firefox.

userChrome.css

/*================================================RECREATION OF THE OLD FIREFOX TITLEBAR================================================*/
/*- Enabling user stylesheets: https://www.reddit.com/r/FirefoxCSS/comments/73dvty/tutorial_how_to_create_and_livedebug_userchromecss/ */

:root {
  --tab-min-height: 26px !important;
}
:root #tabbrowser-tabs {
  --tab-min-height: 26px !important;
}

#toolbar-menubar .titlebar-button {
  padding-block: 0px !important;
}

.tab-background {
  --tab-block-margin: 3px 0 !important;
  --tab-border-radius: 0px !important;
}

.tab-background:is([selected], [multiselected]) {
  background-color: var(--toolbar-bgcolor) !important;
  background-image: var(--toolbar-bgimage) !important;
  
  box-sizing: border-box !important;
  border-top: 2px solid skyblue !important;
}

.tab-close-button {
  background-size: cover !important;
}

.tabbrowser-tab[first-visible-tab="true"] {
  padding-top: 0 !important;
  padding-bottom: 0 !important;
  padding-right: 2px !important;
  padding-left: 0 !important;
}

.tab-close-button {
  margin-top: 5px !important;
}

.tab-text {
  margin-top: 3px !important;
}

.tab-icon-image {
  margin-top: 5px !important;
}

.tab-icon-overlay {
  margin-top: 5px !important;
}

.tab-secondary-label {
  display: none !important;
}