NightOwl, a Firefox extension, forces dark mode on all websites using CSS inversion, with per-domain toggles to respect native dark themes on sites like GitHub and Figma. The tool has gained traction for its simplicity and privacy focus, but it has also sparked controversy over design integrity and OLED power savings.

Users are divided on whether CSS inversion is the best approach. Some argue it can break site layouts, while others praise it for OLED efficiency. A privacy-conscious user highlighted that NightOwl operates locally with no telemetry, making it a standout option compared to other dark mode tools. Meanwhile, developers note that it differs from setting prefers-color-scheme via about:config because it works on all sites regardless of native dark mode support.

The community consensus is that NightOwl is a useful, privacy-friendly tool for enforcing dark mode, but there are clear fault lines over its impact on design and user experience. While some appreciate its simplicity and local operation, others remain skeptical about its broader implications for web standards and device efficiency.