Joomla ships Bootstrap 5 as its UI framework, but the frontend only loads the JavaScript modules — not the CSS. Third-party extensions often include their own Bootstrap styles, which assume a white background. Signal Dark intercepts this by overriding every Bootstrap component class with dark-appropriate colours, borders, and shadows.
Alerts use the template's semantic colours: emerald for success, amber for warning, rose for danger, cyan for info. Badges, buttons, and form controls all inherit the dark surface and violet focus rings. Tables get striped rows that actually work on dark backgrounds. Pagination, accordions, tabs, dropdowns, and modals — everything is reskinned so extensions look native from the moment they render.