Browser support

Admin UI

The Astropress admin UI uses modern browser APIs including Custom Elements v1 and the native <dialog> element with showModal(). The following minimum versions are required:

Browser	Minimum version	Release date
Chrome / Chromium	108+	Nov 2022
Edge (Chromium)	108+	Nov 2022
Firefox	98+	Mar 2022
Safari / WebKit	15.4+	Mar 2022

Key API requirements:

API	Chrome	Firefox	Safari
Custom Elements v1	54+	63+	10.1+
<dialog> + showModal()	37+	98+	15.4+
CSS Custom Properties	49+	31+	9.1+
crypto.randomUUID()	92+	95+	15.4+

Older browsers that do not support <dialog> will not get a keyboard-trapping modal (the confirm-dialog web component falls back to native <form method="dialog"> without a focus trap). Form submission continues to work correctly.

Public site

The static production site generated by Astropress is plain HTML/CSS with optional JavaScript via Pagefind (search). It works in any browser that supports CSS Grid and Flexbox (IE 11 is not supported, but all browsers released after 2016 are fine).

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browserslist config

The following browserslist configuration is set in the root package.json and consumed by any build tools that respect it:

"browserslist": [
  "Chrome >= 108",
  "Firefox >= 98",
  "Safari >= 15.4",
  "Edge >= 108"
]

This applies only to the admin UI JS bundle. The public static site uses no framework JS and ships no polyfills.

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Testing matrix

The test suite exercises two browser engines:

Project	Engine	Scope
admin-harness (Chromium)	Blink	Admin interactions, accessibility, form validation
admin-harness-firefox	Gecko	Accessibility cross-check, dialog behaviour
example-accessibility (Chromium)	Blink	Public site accessibility
Mobile (iPhone 13, Galaxy S5)	WebKit / Blink	Responsive layout

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Known limitations

• RTL (Right-to-Left) — The admin UI uses physical direction CSS properties (margin-left, text-align: left) in several places. RTL scripts are not currently supported.
• Screen magnification — The layout is tested at 100% zoom. High zoom levels (400%) may cause horizontal overflow in some admin table views.
• High-contrast mode — The CSS custom property palette respects prefers-contrast: more on Chrome/Edge. Firefox and Safari may show reduced contrast at extreme zoom with forced colours enabled.