Apply suggestions from code review

Co-authored-by: Chauncey McAskill <chauncey@mcaskill.ca>

assets/styles/objects/_grid.scss

@@ -3,8 +3,9 @@
 // ==========================================================================
 // Help: https://css-tricks.com/snippets/css/complete-guide-grid/
 //
-// How to use :
 /**
+ * Usage:
+ *
  * ```html
  * <div class="o-grid -col-4 -col-12@from-medium -gutters">
  *     <div class="o-grid_item u-gc-1/2 u-gc-3/9@from-medium">
@@ -15,7 +16,7 @@
  *     </div>
  * </div>
  * ```
-**/
+ */
 
 .o-grid {
     display: grid;

build/tasks/styles.js

@@ -146,7 +146,7 @@ export default async function compileStyles(sassOptions = null, postcssOptions =
                 await writeFile(outfile, result.css).then(() => {
                     // Purge CSS once file exists.
                     if (outfile) {
-                        purgeUnusedCSS(outfile, filestem);
+                        purgeUnusedCSS(outfile, `${label || `${filestem}.css`}`);
                     }
                 });
 
@@ -220,15 +220,17 @@ function createPostCSSProcessor(pluginsListOrMap, options)
 }
 
 /**
- * Purge unused styles of minified CSS files.
+ * Purge unused styles from CSS files.
  *
  * @async
  *
- * @param  {string} outfile  - The path of the CSS file.
- * @param  {string} filestem - The CSS file name.
+ * @param  {string} outfile - The path of a css file
+ *      If missing the function stops.
+ * @param  {string} label   - The CSS file label or name.
+ * @return {Promise}
  */
-async function purgeUnusedCSS(outfile, filestem) {
-
+async function purgeUnusedCSS(outfile, label) {
+    label = label ?? basename(outfile);
     const timeLabel = `${filestem}.css purged in`;
     console.time(timeLabel);
 
@@ -247,6 +249,6 @@ async function purgeUnusedCSS(outfile, filestem) {
     for(let result of purgeCSSResults) {
         await writeFile(outfile, result.css)
 
-        message(`${filestem}.css purged`, 'chore', timeLabel);
+        message(`${label} purged`, 'chore', timeLabel);
     }
 }

docs/grid.md

@@ -1,12 +1,10 @@
 # Grid system
 
-* [Architectures](#architectures)
-  * [Styles](#styles)
+* [Architectures](#architecture)
   * [Build tasks](#build-tasks)
-    * [Config file](#config-file)
+    * [Configuration](#configuration)
 * [Usage](#usage)
   * [Example](#example)
-* [Limitations](#limitations)
 
 ## Architecture