fix: Lighthouse a11y + CLS issues on homepage

website/src/components/card-grid.js

@@ -90,16 +90,21 @@ function renderCategorySection(category, allAnchors) {
       </h2>
 
       <div class="anchor-cards-grid">
-        ${categoryAnchors.map((anchor) => renderAnchorCard(anchor, color)).join('')}
+        ${categoryAnchors.map((anchor) => renderAnchorCard(anchor, color, category.id)).join('')}
       </div>
     </section>
   `
 }
 
 /**
- * Render a single anchor card
+ * Render a single anchor card.
+ *
+ * The optional `categoryId` argument is used to namespace the heading id
+ * used by `aria-labelledby`, since the same anchor may appear in multiple
+ * category sections (anchors can belong to more than one category) and
+ * the DOM must not contain duplicate ids.
  */
-function renderAnchorCard(anchor, categoryColor) {
+function renderAnchorCard(anchor, categoryColor, categoryId) {
   const isUmbrella = anchor.subAnchors && anchor.subAnchors.length > 0
   const umbrellaClass = isUmbrella ? ' anchor-card-umbrella' : ''
   const rolesCount = anchor.roles ? anchor.roles.length : 0
@@ -110,19 +115,21 @@ function renderAnchorCard(anchor, categoryColor) {
   const editTitle = i18n.t('card.edit')
   const copyLinkTitle = i18n.t('card.copyLink')
   const safeId = escapeHtml(anchor.id)
+  const safeCategoryId = escapeHtml(categoryId || 'uncat')
+  const cardTitleId = `anchor-card-title-${safeCategoryId}-${safeId}`
 
   return `
-    <article
+    <div
       class="anchor-card${umbrellaClass}"
       data-anchor="${safeId}"
       data-roles="${escapeHtml(anchor.roles ? anchor.roles.join(',') : '')}"
       data-tags="${escapeHtml(anchor.tags ? anchor.tags.join(',') : '')}"
       tabindex="0"
       role="button"
-      aria-label="${escapeHtml(i18n.t('card.openDetails').replace('{title}', anchor.title))}"
+      aria-labelledby="${cardTitleId}"
     >
       <div class="anchor-card-header">
-        <h3 class="anchor-card-title">${escapeHtml(anchor.title)}</h3>
+        <h3 id="${cardTitleId}" class="anchor-card-title">${escapeHtml(anchor.title)}</h3>
         <div class="flex gap-1">
           <button
             class="anchor-copy-link-btn"
@@ -215,7 +222,7 @@ function renderAnchorCard(anchor, categoryColor) {
       </div>
 
       <div class="anchor-card-indicator" style="background-color: ${categoryColor}"></div>
-    </article>
+    </div>
   `
 }
 

website/src/components/header.js

@@ -11,7 +11,7 @@ export function renderHeader() {
           <!-- Logo left, spanning both rows -->
           <div class="flex items-center">
             <a href="#/" class="no-underline flex flex-col items-center">
-              <img src="${import.meta.env.BASE_URL}logo.png" alt="Semantic Anchors" class="max-h-24" />
+              <img src="${import.meta.env.BASE_URL}logo.png" alt="Semantic Anchors" width="218" height="96" class="max-h-24 w-auto" />
               <span class="text-xs text-[var(--color-text-secondary)] leading-tight" data-i18n="header.slogan">${i18n.t('header.slogan')}</span>
             </a>
             <button
@@ -54,7 +54,8 @@ export function renderHeader() {
                 <button
                   id="lang-toggle"
                   class="rounded-md px-2 py-1 text-sm font-medium text-[var(--color-text-secondary)] hover:text-[var(--color-text)] hover:bg-[var(--color-bg-secondary)] transition-colors"
-                  aria-label="Toggle language"
+                  aria-label="${i18n.t('header.langToggleAria')}"
+                  data-i18n-aria="header.langToggleAria"
                 >${langLabel}</button>
                 <button
                   id="theme-toggle"
@@ -82,6 +83,8 @@ export function renderHeader() {
               />
               <select
                 id="header-role-filter"
+                aria-label="${i18n.t('filter.allRoles')}"
+                data-i18n-aria="filter.allRoles"
                 class="rounded-lg border-2 border-[var(--color-border)] bg-[var(--color-bg)] px-4 py-2 text-base text-[var(--color-text)] focus:outline-none focus:ring-2 focus:ring-[var(--color-primary)] focus:border-[var(--color-primary)] transition-colors duration-300"
               >
                 <option value="" data-i18n="filter.allRoles">${i18n.t('filter.allRoles')}</option>
@@ -97,7 +100,7 @@ export function renderHeader() {
         <div class="sm:hidden">
           <div class="flex flex-col items-center">
             <a href="#/" class="no-underline flex flex-col items-center">
-              <img src="${import.meta.env.BASE_URL}logo.png" alt="Semantic Anchors" class="max-h-16" />
+              <img src="${import.meta.env.BASE_URL}logo.png" alt="Semantic Anchors" width="145" height="64" class="max-h-16 w-auto" />
               <span class="text-xs text-[var(--color-text-secondary)] leading-tight text-center" data-i18n="header.slogan">${i18n.t('header.slogan')}</span>
             </a>
             <div class="flex items-center gap-3 mt-2">
@@ -117,7 +120,8 @@ export function renderHeader() {
               <button
                 id="lang-toggle-mobile"
                 class="rounded-md px-2 py-1 text-sm font-medium text-[var(--color-text-secondary)] hover:text-[var(--color-text)] hover:bg-[var(--color-bg-secondary)] transition-colors"
-                aria-label="Toggle language"
+                aria-label="${i18n.t('header.langToggleAria')}"
+                data-i18n-aria="header.langToggleAria"
               >${langLabel}</button>
               <button
                 id="theme-toggle-mobile"

website/src/components/onboarding-modal.js

@@ -101,7 +101,7 @@ function buildModalContent() {
       </div>
 
       <div class="text-center px-6 pb-4">
-        <img src="${baseUrl}logo.png" alt="Semantic Anchors" class="h-24 mx-auto mb-3" />
+        <img src="${baseUrl}logo.png" alt="Semantic Anchors" width="218" height="96" class="h-24 w-auto mx-auto mb-3" />
         <h2 id="onboarding-title" class="text-lg font-medium text-[var(--color-text-secondary)]">
           ${slogan2}
         </h2>

website/src/styles/main.css

@@ -65,6 +65,13 @@ body {
   font-family: Inter, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
 }
 
+/* Reserve viewport height so the browser doesn't shift layout when the
+   card grid / doc content loads asynchronously. This is the single biggest
+   lever for Cumulative Layout Shift on the homepage (Lighthouse weight 25). */
+#page-content {
+  min-height: calc(100vh - 12rem);
+}
+
 /* Force sans-serif on all card descendants to override AsciiDoc serif fonts */
 .anchor-card,
 .anchor-card *,
@@ -164,6 +171,10 @@ body {
   @apply flex items-center gap-1;
   @apply px-2 py-1 rounded;
   @apply bg-gray-100 dark:bg-gray-700;
+  /* Explicit text color for WCAG AA contrast on the badge background.
+     Default .anchor-card-meta text (gray-500/400) only reaches ~3.9:1 / ~3.1:1,
+     below the 4.5:1 threshold for normal text. */
+  @apply text-gray-700 dark:text-gray-200;
 }
 
 .feedback-badge {

website/src/translations/de.json

@@ -2,6 +2,7 @@
   "app.title": "Semantic Anchors",
   "app.description": "Gemeinsames Vokabular für LLM-Kommunikation",
   "header.langToggle": "EN",
+  "header.langToggleAria": "EN — zu Englisch wechseln",
   "header.slogan": "Ein Wort, und die KI versteht den Rest.",
   "header.themeToggle.dark": "Zum Dunkelmodus wechseln",
   "header.themeToggle.light": "Zum Hellmodus wechseln",

website/src/translations/en.json

@@ -2,6 +2,7 @@
   "app.title": "Semantic Anchors",
   "app.description": "Shared vocabulary for LLM communication",
   "header.langToggle": "DE",
+  "header.langToggleAria": "DE — switch to German",
   "header.slogan": "One word, and the AI gets the rest.",
   "header.themeToggle.dark": "Switch to dark mode",
   "header.themeToggle.light": "Switch to light mode",