A minimal Manifest V3 Chrome extension that restores Gmail's gold importance markers. It injects one stylesheet on https://mail.google.com/* and uses a bundled image. No JavaScript, backend, analytics, or Gmail API access.
How it works
content.css selects the final direct div child of [role="switch"][data-is-important="true"] and replaces only its background image. Gmail retains control of size, position, clicks, tooltips, and importance state. CSS also applies to matching elements inserted during navigation.
The selector avoids Gmail's variable class names and localized accessible labels. It assumes the icon is the final direct div child, as in the supplied Gmail markup. Gmail's internal DOM is not a public API; different layouts or future changes may require a selector update. This initial version covers these importance switches, not every importance-related icon in Gmail's sidebar or menus.
The image is exposed only to Gmail through web_accessible_resources. The extension makes no image download at runtime and does not read or transmit email. Chrome may display a site-access warning because its stylesheet modifies Gmail.