I have no idea why, but you can adjust them directly in the system-icons.css file, look for -gnome-icons-hack-filter & -gnome-window-icons-hack-filter vars and play with css filters. There is also a white-list feature which enables you to exclude a desired domain from dark mode. If you do not like the current dark theme, please visit the options page and choose a different theme from over 50 available options. add -theme-override string key at about:config and set theme for content. You can also: set -gtk-dark-theme to true at about:config to disable dark theme autoconfiguration. After you follow the instructions in this article, you will be able to get the dark theme in Firefox 35 and above. Please run in terminal as MOZLOG'Widget:5' firefox > log.txt 2>&1 and attach the log here. Here is a trick which will allow you to use this dark theme for Firefox stable builds. Icons might appear black where they should be white on some systems. Toolbar button serves as an ONOFF switch which enables you to easily and quickly turn the extension ON or OFF. The Developer edition of the Mozilla Firefox browser comes with a different, dark theme. Make all tab icons look kinda like symbolic icons. Use system theme icons instead of Adwaita icons included by theme. Limit the URL bar's autocompletion popup's width to the URL bar's width.

You should move the new tab button somewhere else for this to work, because by default it is on the tab bar too. Many people prefer dark modes in apps as the dark UI or black UI reduces eye strain and allows people to use the apps for long time specially at night time. Hide the tab bar when only one tab is open. Mozilla Firefox web browser comes with built-in Dark theme mode which allows users to enjoy dark mode or night mode in Firefox without installing any extra extension. This no-frills extension lets you entirely switch to dark mode. Those features are not included by default, because can introduce bugs or Firefox functionalities lost. If you want a simple dark mode for your Firefox browser, Dark Mode is one of the simplest extensions for you.

Mozjlla firefox dark theme