Better YouTube Subtitles is a Firefox add-on designed to enhance the YouTube viewing experience through extensive subtitle customization. This subscription-based tool allows users to modify the appearance of subtitles without replacing them, utilizing CSS to improve readability and aesthetics. It offers features accessible directly in the browser and supports hotkeys for quick adjustments, making it ideal for those who frequently watch videos on YouTube.

This add-on provides a broad range of customization options, including adjustments to font properties like name, size, weight, color, and opacity. Users can also change text attributes such as letter and word spacing, line height, and position, as well as background settings including color, opacity, padding, and radius. Collectively, these features create a personalized subtitle experience that caters to individual viewing preferences.