YouTube Subtitle Styler от Sefohui

YouTube Subtitle Styler lets you take full control over how subtitles look on YouTube. Set your preferred font, size, text color, background color and opacity, bold, italic, and text shadow — then save once and never worry about YouTube resetting your preferences again.

Styles are enforced using CSS injection with a MutationObserver that automatically reapplies your settings if YouTube tries to override them. All settings are stored locally and applied instantly on every YouTube page you visit.

No account required. No data collected. Open source.

GitHub: https://github.com/Sefohui/youtube-subtitle-styler