Custom CSS Injector – custom styles per domain

Inject custom CSS per domain. A minimalist, ultra-efficient extension to style any website without bloat or heavy features.

Inject custom CSS on any website, domain by domain, with a minimalist, lightweight extension that just works. Custom CSS Injector is a practical tool for developers, designers, and power users who want to personalize any site in seconds, without heavy devtools or bloated extensions. KEY FEATURES • Rules per domain: write custom CSS for each domain and have it applied automatically every time you visit the site. • Ultra lightweight: one of the smallest extensions in the store, carefully built to use minimal memory, CPU and battery. • Clean editor: a focused interface free of distractions, designed for fast edits and quick tweaks. • Smart application: styles are applied on page load and across tabs and frames (iframes) so your changes stay consistent as you browse. • Toggle in one click: instantly enable or disable your custom styles when you need to compare with the original site. • Reset in one click: clear a domain's custom styles in seconds if you want to start fresh. MINIMALIST BUT POWERFUL Custom CSS Injector is intentionally small and efficient, with no trackers, no ads, and no unnecessary UI. Every feature is focused on one job: giving you reliable CSS overrides for each site that feel invisible until you need them. Instead of a cluttered interface with dozens of panels, you get a fast, simple editor that lets you jump straight to the CSS and see the result on the page. PERFECT FOR • Developers adjusting layouts, testing CSS fixes, or overriding styles on staging and production. • Designers adjusting spacing, typography or colors on live sites to explore ideas quickly. • Power users who want to hide distracting elements, darken bright pages, or make any site feel more comfortable to use. WHY THIS EXTENSION • Minimalist: no unnecessary background scripts, no complex onboarding, no feature overload. • Efficient: designed to stay light on resources, even with many domains configured. • Focused: does one thing extremely well, custom CSS per domain, instead of trying to be a toolbox that does everything. Whether you just want to hide a single banner or maintain a long list of custom tweaks across your favorite sites, Custom CSS Injector gives you a fast, reliable and effortless way to do it. Built on Chrome's modern Scripting API for stable, predictable behavior on modern websites.