1. CSS and JavaScript injection
Define a URL pattern, write CSS and/or JS code — the extension injects it automatically every time the page loads. Each rule has its own editor with syntax highlighting (CodeMirror).
- CSS injected via
<style>tag in document head — full specificity available. - JS executed in the page's MAIN world via
chrome.scripting.executeScript— bypasses CSP in 99% of cases, has access towindow. - Activate / deactivate individual rules with one click on the floating toolbar.
- Editor has dark/light theme, line numbers, search and a draggable resize bar.