How Firefox Dark Mode Works and How to Extend It Across More Websites

Firefox's dark mode setting signals the prefers-color-scheme preference, so only sites that support this CSS media query switch to a dark design automatically. Many smaller, older, and corporate sites lack this support and stay light, while the browser's own interface can be darkened separately through its themes panel or a third-party theme. To cover remaining sites, users can enable a browser-level override in about:config, though it inverts colors bluntly, or install an extension such as Dark Reader for more polished results. The guide recommends combining native dark mode with Dark Reader for sites that lack it, noting that dark interfaces can also save power on OLED screens. It adds that the evidence on dark mode and eye strain is more nuanced than marketing claims suggest, depending on lighting conditions.