StyleInject – Custom CSS Injector

Write custom CSS for any website. Rules save per domain and inject automatically on every visit. Restyle, hide, or fix any webpage.

StyleInject lets you write custom CSS rules for any website and have them automatically injected on every visit. Create per-domain rules using simple glob patterns — example.com, *.example.com, or * for all pages. Changes apply live as you type, with a real-time preview before saving. Built-in CSS editor features syntax highlighting, line numbers, auto-formatting, and 12 ready-made snippets for common tasks like hiding cookie banners, widening reading columns, or applying dark mode. Rules can be toggled on/off individually or all at once. Export and import your rule library as JSON.