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Documentation

Browser support

Calaca UI targets Baseline, the features that work in every major browser. Newer features come with a small polyfill or a fallback.

Baseline

Calaca UI uses web features that are Baseline widely available: they work in the current and previous versions of Chrome, Edge, Firefox and Safari, on desktop and mobile. That replaces a list of browser versions that would age.

Calaca is built with Tailwind CSS 4, which needs Safari 16.4, Chrome 111 and Firefox 128 or newer. The same limit applies to Calaca.

Newer features

A feature that is not Baseline yet is used only with a fallback: a feature check or a polyfill. The markup is always the standard HTML, so a polyfill can be deleted once every browser supports the feature, without changing a class or an attribute.

Today there is one polyfill:

  • Invoker commands (commandfor and command on a button) open and close dialogs without JavaScript in browsers that support them. ca-commands.js (458 bytes) adds the same behavior elsewhere and does nothing in browsers that already have it.

And one fallback:

  • Anchor positioning places the dropdown menu under its button. Browsers without it show the menu in the middle of the screen, the popover default; it opens, closes and returns focus the same way.

Tested browsers

Every change is tested in Chromium, Firefox and WebKit, in plain HTML, Astro and Next.js.

In Safari, the Tab key skips buttons by default. Visitors reach them with Option+Tab, or after turning on “Press Tab to highlight each item on a webpage” in Safari’s settings. This is Safari behavior, not a Calaca setting.