Responsive CSS utility classes stripped from stylesheet in Astro 6 build #404

Description

@playform/inline removes responsive utility classes (e.g. md:flex, md:block, md:flex-row, md:cursor-zoom-in) from the main CSS stylesheet during post-build processing. These classes are inside @media (min-width: 768px) blocks and are used in the HTML, but the plugin incorrectly treats them as unused and strips them.

This causes elements with hidden md:flex to remain display: none on desktop, since the md:flex rule is gone.

Reproduction

Environment:

• @playform/inline: 0.1.4
• @playform/compress: 0.2.2
• astro: 6.0.5
• vite: 8.0.0
• unocss: 66.6.6

Steps:

1. Use responsive UnoCSS utilities in Astro components:

<button class="hidden md:flex items-center">Click</button>

2. Run astro build
3. Before @playform/inline runs, the CSS file contains all responsive utilities correctly:

.md\:flex { display: flex }
.md\:block { display: block }
.md\:flex-row { flex-direction: row }
/* ... many more md:* classes */

4. After @playform/inline processes the build, these classes are removed from the stylesheet

Verification: Disabling @playform/inline in astro.config.mjs results in all responsive classes being present and working correctly.

Expected behavior

@playform/inline should preserve CSS rules inside @media blocks that match classes used in the HTML, even if the media query doesn't apply at the "default" viewport.

Additional context

• Non-responsive utilities like .hidden, .flex, .absolute are preserved correctly
• A few responsive utilities survive (e.g. md:text-xs) — possibly because they're inlined into the HTML before the main CSS is pruned
• This was working with Astro 5 / Vite 7 — the regression appeared after upgrading to Astro 6 / Vite 8