diff --git a/components/utilities/versionSelector.module.css b/components/utilities/versionSelector.module.css
index c55252851..fca811e65 100644
--- a/components/utilities/versionSelector.module.css
+++ b/components/utilities/versionSelector.module.css
@@ -1,9 +1,8 @@
 .Container {
-  @apply flex items-center gap-2 mb-4;
+  @apply flex items-center gap-2 mb-4 z-dropdown;
   /* Sticky positioning - stays in place as you scroll */
   position: sticky;
   top: 0.5rem;
-  z-index: 50; /* See z-index reference in styles/globals.css */
   width: fit-content;
   align-self: flex-start;
 }
@@ -66,7 +65,7 @@
 
 /* Dropdown menu - solid background matching site */
 .DropdownMenu {
-  @apply absolute top-full left-0 mt-1 rounded-md list-none m-0 min-w-full z-50;
+  @apply absolute top-full left-0 mt-1 rounded-md list-none m-0 min-w-full z-dropdown;
   @apply bg-white border-none;
   padding: 0.375rem 0;
   box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
diff --git a/styles/globals.css b/styles/globals.css
index 3ca5e086e..c14f9d5cc 100644
--- a/styles/globals.css
+++ b/styles/globals.css
@@ -6,27 +6,25 @@
  * ==========================================================================
  * Z-INDEX REFERENCE
  * ==========================================================================
- * Use this scale to maintain consistent stacking order across the site.
- * When adding new z-index values, update this reference.
+ * Semantic z-index classes are defined in tailwind.config.js under theme.extend.zIndex
+ * Use these class names instead of numeric values (z-10, z-20, etc.)
  *
- * z-50  - Version selector (sticky container & dropdown menu)
- *       - Theme toggle tooltip
+ * z-dropdown (50) - Version selector, tooltips, dropdown menus
+ *                   Files: versionSelector.module.css, themeToggle.module.css
  *
- * z-30  - Header navigation (header.module.css)
- *       - Image lightbox overlay (image.module.css)
- *       - Chat sticky button (chatSticky.module.css)
+ * z-header (30)   - Header navigation, overlays, sticky elements
+ *                   Files: header.module.css, image.module.css, chatSticky.module.css
  *
- * z-20  - Sidebar navigation (sideBar.module.css)
- *       - Image lightbox close button (image.module.css)
- *       - RefCard containers (refCard.module.css)
+ * z-sidebar (20)  - Sidebar, refcards, secondary overlays
+ *                   Files: sideBar.module.css, image.module.css, refCard.module.css
  *
- * z-10  - Code block elements (code.module.css, autofunction.module.css)
- *       - Search modal & search box (search.module.css, searchModal.css)
- *       - Floating nav & gradients (floatingNav.module.css, sideBar.module.css)
- *       - Nav icons (navChild.module.css)
- *       - Component slider elements (componentSlider.module.css)
+ * z-elevated (10) - Code blocks, search, floating nav, nav icons
+ *                   Files: code.module.css, autofunction.module.css, search.module.css,
+ *                          floatingNav.module.css, navChild.module.css, componentSlider.module.css
  *
- * z-0   - Line highlights in code blocks (base layer)
+ * z-base (0)      - Default layer, code line highlights
+ *
+ * z-modal (100)   - Reserved for modals and dialogs (future use)
  * ==========================================================================
  */
 
diff --git a/tailwind.config.js b/tailwind.config.js
index f1ad5e345..32d5543db 100644
--- a/tailwind.config.js
+++ b/tailwind.config.js
@@ -181,6 +181,17 @@ module.exports = {
     },
 
     extend: {
+      // Semantic z-index scale for consistent stacking order
+      // See styles/globals.css for usage documentation
+      zIndex: {
+        base: "0", // Default layer, code line highlights
+        elevated: "10", // Code blocks, search, floating nav, nav icons
+        sidebar: "20", // Sidebar, refcards, lightbox close button
+        header: "30", // Header, lightbox overlay, chat sticky
+        dropdown: "50", // Version selector, tooltips, dropdown menus
+        modal: "100", // Modals, dialogs (reserved for future use)
+      },
+
       minWidth: {
         56: "14rem",
       },