Get theme updates and move the styles to @use - #564

Part of SpineEventEngine/site-commons#38.

This PR moves the site to the Dart Sass theme and its own styles to the Sass module system. It also brings in the JavaScript dependency updates from #558 and #560.

Changes

1. Get theme updates. site-commons goes from b79100d to 9216e48. That brings in:
   • Serve jQuery as a file so Lychee checks body links site-commons#39: jQuery is served as a file instead of being inlined in every page.
   • Compile the styles with Dart Sass site-commons#40: the theme compiles with Dart Sass.
   • Move the theme styles from @import to @use site-commons#41: the theme moves to @use/@forward.
2. JavaScript dependencies. These are Dependabot's commits, cherry-picked:
   • source-map-js 1.2.1 → 1.2.2 (Bump source-map-js from 1.2.1 to 1.2.2 in /site #558).
   • postcss-selector-parser 6.1.4 → 7.1.6 and @fullhuman/postcss-purgecss 7.0.2 → 8.0.0 (Bump postcss-selector-parser and @fullhuman/postcss-purgecss in /site #560). Nothing in the site or the theme loads PurgeCSS. The CSS is byte-identical with and without these bumps.
   • Together they resolve the two open Dependabot alerts on master: source-map-js (high) and postcss-selector-parser (moderate).
3. Move the styles from @import to @use. main.scss loads the theme and its partials with @use, in the same order, so the CSS comes out in the same order. Each partial loads what it uses:
   • the theme, through @use "theme-main" as *;;
   • other partials, by relative paths: base/colors, base/common for %expandable-title, and modules/forms for $form-error-color. main.scss loads each of them before the partials that use them, so no CSS moves.
4. Replace deprecated Sass functions. map-get() → map.get(). fade-out() → color.adjust($alpha: …), which computes the same color.
5. Keep Check Links passing. Lychee couldn't extract links past the jQuery inlined in every page's <head>. With site-commons#39, it reads whole pages, and it finds 14 links that were already broken:
   • The Gitter link in the 1.0 release post now points to where Gitter redirects. Lychee rejects the old URL's 301.
   • A new .lycheeignore lists the 13 links broken in the docs this site imports, as Get theme updates documentation#96 does. One comes from documentation itself and is fixed by that PR. The other 12 come from the validation docs (Remove the validation links from .lycheeignore once they are fixed documentation#97). Each pattern should go once the module update that fixes its link lands here.
   • Check Links also runs when .lycheeignore changes. config distributes check-links.yml, so Run Check Links when .lycheeignore changes config#826 adds the same trigger there. Until it merges, ./config/pull drops the line.
6. Update config. It brings Move check-links off Node.js 20 and show Lychee's report on the run page config#825: newer action versions in Check Links, and a step that shows Lychee's report on the run page.

Sass warnings

Hugo hides deprecations in every file except the entry one (silenceDependencyDeprecations), so the CLI is what shows the partials. All 52 deprecations the site owned are gone: 35 @imports, 9 map-gets and 4 fade-outs, each fade-out reported twice.

CSS comparison

I flattened public/main.min.*.css into one context | selector | declaration line per declaration and diffed the results.

master → theme update: 12,764 declarations on both sides. After normalizing Dart Sass formatting and precision (fractional RGB channels, spaces in custom properties, quotes, hsla() vs rgba(), literal characters instead of escapes), what's left:

• calc() is folded: .ratio-* aspect ratios, .toc-col width.
• The code-tab indicator gets border-radius: 1px. LibSass emitted an invalid calc($indicator-line-height / 2).
• No more .h1–.h6, .small or .mark variants of selectors. Bootstrap's @extends no longer reach outside Bootstrap. No page uses those classes.
• The medium Roboto Mono .eot source now points to fonts/robotomono/, where the file is (site-commons#41).
• 13 Bootstrap .table-* variant colors differ by one unit in one channel. LibSass rounded the intermediate mix() results.
• --code-block-padding and --table-* now sit in rule blocks of their own, because Dart Sass emits declarations that follow nested rules in place. Each still comes before its overrides and uses.

Theme update → this PR: all 12,764 declarations match. The only change is that the @extend %expandable-title rule lists .licenses .collapse-link and .licenses .collapsible-panel-title in the other order, which has no effect. map.get() and color.adjust() produce the same values as the functions they replace.

Leading license comment

The minified CSS now starts with the theme's license comment instead of Bootstrap's MIT banner. theme-main.scss has a /*! header, which Dart Sass dropped under @import but emits first under @use. The theme's PostCSS step (discardComments({removeAllButFirst: true})) keeps only that first comment. The theme's own preview-main.scss already works this way. The fix belongs in site-commons.

Checks

• hugo --minify and hugo -e development build.
• npm test: 42 tests pass.
• Lychee 0.24.2 with lychee.toml over the development build: 14,664 links, none broken apart from the ignored ones.

🤖 Generated with Claude Code