The headline addition is `text-fit`, which scales a font to fill its container's horizontal width — the kind of thing you've been doing with JavaScript resize observers or the clamp() trick, now handled in CSS. Pair it with a headline element and the font just fits, no JS. `AccentColor` and `AccentColorText` system color keywords let you read the user's OS accent color directly in CSS, which opens up genuinely native-feeling UI theming without any JS bridge. The `light-dark()` function already handled color switching by scheme; it now accepts image values too, so you can swap a logo or illustration based on dark/light mode in a single declaration. The container query comma syntax rounds out the release — it lets you express fallback queries for features that may not be supported in all container contexts, closer in spirit to `@supports` than the selector-list comma you might expect.