fix: pin Tailwind config path + absolute content globs (cwd-independent PostCSS for CI)

postcss.config.js

@@ -2,10 +2,18 @@
  * PostCSS configuration used by Hugo Pipes (css.PostCSS) AND the standalone
  * `npm run build:css` step. Requires the `postcss-cli` devDependency so Hugo
  * can shell out to the local `postcss` binary during the asset pipeline.
+ *
+ * The Tailwind config path is pinned to this file's directory. Tailwind v3
+ * otherwise resolves tailwind.config.js relative to process.cwd(); when Hugo's
+ * PostCSS pipeline runs with a cwd other than the project root (notably in CI),
+ * the config is not found, `content` is empty, and @apply'd utilities like
+ * `text-secondary` fail with "class does not exist". Pinning it fixes that.
  */
+const path = require("path");
+
 module.exports = {
   plugins: {
-    tailwindcss: {},
+    tailwindcss: { config: path.join(__dirname, "tailwind.config.js") },
     autoprefixer: {},
   },
 };