6.0.0 — readable danger, readable progress, a sidebar that looks like a panel

Three things you can see, which is what makes this a major. Nothing is renamed, nothing is removed, and every change is a default you can put back in one declaration — see MIGRATION.md.

Changed

• --retro-danger is #cc0000, and its on-fill text is white. The fill was pure #ff0000, where white scores 4.00:1 and black 5.25:1 — so every danger button, badge, alert and toast carried black text. That passes the arithmetic and reads like a label printed on a fire extinguisher. On #cc0000 white scores 5.89:1. Hover and active moved with it. Old pair: :root { --retro-danger: #ff0000; --retro-danger-fg: #000; }
• The progress label carries a plate. It straddles the filled bar and the empty track, which are always opposite in lightness, and the text-shadow halo lost against the striped navy bar. The label now sits on a small bordered plate in the track colour.
• The sidebar is a panel. Raised chassis, a title bar painted like the one over a code block, group bands framed as the head of the list they introduce, sidebar lists framed like the navs beside them, and one rhythm spacing the widgets.

Added

• [aria-current] lights a .retro-nav-item the way .active does — a router or static site generator marks the current page that way and used to get no highlight.

Documentation

• A trademark notice. RetroCSS imitates the look of mid-1990s desktop software; it is independent, unaffiliated and unendorsed, and ships no Microsoft artwork, icon, font or code. Product-facing copy now says Win9x or mid-90s desktop; prose explaining how Windows itself behaved still names it, because that is what those sentences are about.

All five gates pass: 36 unit tests, 370 token pairs at AA, the stylesheet gate, 140 rendered-page checks, 20 keyboard loads.