FirefoxCSS Hub

Published theme

DownToneUI

A modular UI customization for Firefox, using Sidebery for vertical tabs.

Open original repository
Repository
github.com/oviung/DownToneUI-Firefox
Stars
63
Last update
Mar 9, 2026
Submitted as
legacy
DownToneUI screenshot

Tags

darksideberyvertical

Install overview

  1. Open the original repository and read the maintainer's installation notes.
  2. Enable toolkit.legacyUserProfileCustomizations.stylesheets in about:config.
  3. Create or open the chrome folder in your Firefox profile.
  4. Copy the theme files requested by the original repository and restart Firefox.

Ownership note

FirefoxCSS Hub indexes this submission for discovery. The code, license, support, and installation details belong to the original repository.