diff --git a/src/static/css/style.css b/src/static/css/style.css
index 52978bb..05401c9 100644
--- a/src/static/css/style.css
+++ b/src/static/css/style.css
@@ -1704,6 +1704,72 @@ a.dev-source-pill:hover {
     border-radius: var(--radius);
     background: var(--bg-primary);
     border: 1px solid var(--border);
+    cursor: pointer;
+    transition: border-color 0.15s ease, background 0.15s ease;
+    outline: none;
+}
+.source-overview-item:hover {
+    border-color: var(--accent);
+    background: var(--bg-elevated);
+}
+.source-overview-item:focus-visible {
+    box-shadow: 0 0 0 2px var(--tint-accent-strong);
+}
+.source-overview-item.active {
+    border-color: var(--accent);
+    background: var(--tint-accent-subtle);
+    box-shadow: var(--glow-accent);
+}
+
+/* Inline-Aufklapp-Bereich (volle Reihen-Breite, direkt unter dem geklickten Item) */
+.source-overview-detail {
+    grid-column: 1 / -1;
+    padding: var(--sp-md) var(--sp-lg);
+    background: var(--bg-elevated);
+    border: 1px solid var(--accent);
+    border-radius: var(--radius);
+    animation: source-detail-in 0.18s ease;
+}
+@keyframes source-detail-in {
+    from { opacity: 0; transform: translateY(-4px); }
+    to   { opacity: 1; transform: translateY(0); }
+}
+.source-overview-detail-empty {
+    font-size: 12px;
+    color: var(--text-tertiary);
+    font-style: italic;
+}
+.source-overview-detail-list {
+    list-style: none;
+    margin: 0;
+    padding: 0;
+    display: flex;
+    flex-direction: column;
+    gap: 4px;
+    max-height: 320px;
+    overflow-y: auto;
+}
+.source-overview-detail-list::-webkit-scrollbar { width: 6px; }
+.source-overview-detail-list::-webkit-scrollbar-track { background: var(--bg-primary); border-radius: 3px; }
+.source-overview-detail-list::-webkit-scrollbar-thumb { background: var(--text-disabled); border-radius: 3px; }
+.source-overview-detail-list li {
+    font-size: 12px;
+    line-height: 1.4;
+    padding: 2px 0;
+    border-top: 1px dashed var(--border);
+}
+.source-overview-detail-list li:first-child { border-top: none; }
+.source-overview-detail-list li a {
+    color: var(--text-primary);
+    text-decoration: none;
+}
+.source-overview-detail-list li a:hover {
+    color: var(--accent);
+    text-decoration: underline;
+}
+@media (prefers-reduced-motion: reduce) {
+    .source-overview-detail { animation: none; }
+    .source-overview-item { transition: none; }
 }
 
 .source-overview-name {
diff --git a/src/static/dashboard.html b/src/static/dashboard.html
index 5c0f673..d8b9eee 100644
--- a/src/static/dashboard.html
+++ b/src/static/dashboard.html
@@ -13,7 +13,7 @@
     <link rel="stylesheet" href="/static/vendor/leaflet.css">
     <link rel="stylesheet" href="/static/vendor/MarkerCluster.css">
     <link rel="stylesheet" href="/static/vendor/MarkerCluster.Default.css">
-    <link rel="stylesheet" href="/static/css/style.css?v=20260501e">
+    <link rel="stylesheet" href="/static/css/style.css?v=20260501f">
 <style>
 /* Export Modal Radio */
 .export-radio { display:flex; align-items:center; gap:10px; padding:8px 12px; cursor:pointer; border-radius:var(--radius-sm); transition:background 0.15s; border:1px solid transparent; margin-bottom:4px; }
@@ -647,7 +647,7 @@
     <script src="/static/js/components.js?v=20260427a"></script>
     <script src="/static/js/layout.js?v=20260316b"></script>
     <script src="/static/js/pipeline.js?v=20260501a"></script>
-    <script src="/static/js/app.js?v=20260501e"></script>
+    <script src="/static/js/app.js?v=20260501f"></script>
     <script src="/static/js/cluster-data.js?v=20260322f"></script>
     <script src="/static/js/tutorial.js?v=20260316z"></script>
     <script src="/static/js/chat.js?v=20260422a"></script>
diff --git a/src/static/js/app.js b/src/static/js/app.js
index a9e5b56..17060a2 100644
--- a/src/static/js/app.js
+++ b/src/static/js/app.js
@@ -866,6 +866,54 @@ const App = {
         }
     },
 
+    /** Klick auf eine Quellen-Box: Liste der Artikel inline aufklappen (mutual-exclusive). */
+    toggleSourceOverviewDetail(el) {
+        if (!el) return;
+        const grid = el.parentElement;
+        if (!grid) return;
+        const sourceName = el.dataset.source || '';
+        const wasActive = el.classList.contains('active');
+
+        // Alle anderen schliessen + bestehendes Detail entfernen
+        grid.querySelectorAll('.source-overview-item.active').forEach(it => {
+            it.classList.remove('active');
+            it.setAttribute('aria-expanded', 'false');
+        });
+        const existingDetail = grid.querySelector('.source-overview-detail');
+        if (existingDetail) existingDetail.remove();
+
+        // Wenn das geklickte Item bereits aktiv war: nur schliessen
+        if (wasActive) return;
+
+        // Neues Detail einfuegen direkt nach dem geklickten Item
+        el.classList.add('active');
+        el.setAttribute('aria-expanded', 'true');
+
+        const articles = (this._currentArticles || [])
+            .filter(a => (a.source || 'Unbekannt') === sourceName)
+            .sort((a, b) => {
+                const ta = new Date(a.collected_at || a.published_at || 0).getTime();
+                const tb = new Date(b.collected_at || b.published_at || 0).getTime();
+                return tb - ta;
+            });
+
+        const detail = document.createElement('div');
+        detail.className = 'source-overview-detail';
+        if (articles.length === 0) {
+            detail.innerHTML = '<div class="source-overview-detail-empty">Keine Artikel gefunden.</div>';
+        } else {
+            const items = articles.map(a => {
+                const headline = UI.escape(a.headline_de || a.headline || '(ohne Titel)');
+                if (a.source_url) {
+                    return `<li><a href="${UI.escape(a.source_url)}" target="_blank" rel="noopener">${headline}</a></li>`;
+                }
+                return `<li>${headline}</li>`;
+            }).join('');
+            detail.innerHTML = `<ul class="source-overview-detail-list">${items}</ul>`;
+        }
+        el.insertAdjacentElement('afterend', detail);
+    },
+
     /** Restliche Artikel seitenweise im Hintergrund nachladen und in _currentArticles mergen. */
     async _loadRemainingArticlesInBackground(incidentId) {
         const BATCH = 500;
diff --git a/src/static/js/components.js b/src/static/js/components.js
index 1d39084..89762d0 100644
--- a/src/static/js/components.js
+++ b/src/static/js/components.js
@@ -971,8 +971,9 @@ const UI = {
         html += '<div class="source-overview-grid">';
         data.sources.forEach(s => {
             const langs = (s.languages || ['de']).map(l => (l || 'de').toUpperCase()).join('/');
-            html += `<div class="source-overview-item">
-                <span class="source-overview-name">${this.escape(s.source || 'Unbekannt')}</span>
+            const sourceName = this.escape(s.source || 'Unbekannt');
+            html += `<div class="source-overview-item" data-source="${sourceName}" tabindex="0" role="button" aria-expanded="false" onclick="App.toggleSourceOverviewDetail(this)" onkeydown="if(event.key==='Enter'||event.key===' '){event.preventDefault();App.toggleSourceOverviewDetail(this);}">
+                <span class="source-overview-name">${sourceName}</span>
                 <span class="source-overview-lang">${langs}</span>
                 <span class="source-overview-count">${s.article_count}</span>
             </div>`;