Remove the gap between the tab bar and the window edges and between pinned tabs and unpinned tabs in Firefox

README.md

Annoying Gap Removal in Firefox

Overview

Firefox by default gets shipped with redudant spaces (at least for me). This hack removes the gaps between:

• the tab bar and the window edges
• pinned tabs and unpinned tabs

How?

• Set toolkit.legacyUserProfileCustomizations.stylesheets to true in about:config.
• Create a folder named chrome inside the profile directory (find the Root Directory in about:profiles).
• Copy userChrome.css into the chrome folder you just created.
• Restart Firefox.

Result

References

• GitHub - Remove gap between pinned and unpinned tabs
• Ask Ubuntu - How to remove drag tab in corner of firefox window

userChrome.css

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");


/* Remove the gap between the window edges and the tab bar */
.titlebar-placeholder[type="pre-tabs"],
.titlebar-placeholder[type="post-tabs"],
.titlebar-spacer[type="pre-tabs"],
.titlebar-spacer[type="post-tabs"] {
  display: none !important;
  width: 0px !important;
  max-width: 0px !important;
}

/* Remove the gap between pinned tabs and unpinned tabs */
#tabbrowser-tabs[haspinnedtabs]:not([positionpinnedtabs]) > #tabbrowser-arrowscrollbox > .tabbrowser-tab[first-visible-unpinned-tab] {
  margin-inline-start: 0 !important;
}