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

postcss.config.js

@@ -1,11 +1,19 @@
-/**
- * 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.
- */
-module.exports = {
-  plugins: {
-    tailwindcss: {},
-    autoprefixer: {},
-  },
-};
+/**
+ * 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: { config: path.join(__dirname, "tailwind.config.js") },
+    autoprefixer: {},
+  },
+};