diff --git a/src/frontend/index.html b/src/frontend/index.html
index 6da9ff6..505290a 100644
--- a/src/frontend/index.html
+++ b/src/frontend/index.html
@@ -97,7 +97,17 @@
         .card:hover { transform: translateY(-2px); border-color: var(--accent); box-shadow: var(--shadow); }
         .card-thumb {
             width: 100%; aspect-ratio: 16/10; object-fit: cover;
-            display: block; background: #0d1117;
+            display: block; background: #161b22;
+        }
+        .card-thumb.placeholder {
+            display: flex; flex-direction: column;
+            align-items: center; justify-content: center;
+            aspect-ratio: 16/10;
+            background: #161b22; color: var(--fg-dim); font-size: 32px;
+            text-align: center; padding: 16px; gap: 4px;
+        }
+        .card-thumb.placeholder small {
+            font-size: 12px; color: #484f58;
         }
         .card-body { padding: 10px 12px; }
         .card-filename { font-size: 13px; font-weight: 500; color: var(--fg); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
@@ -254,9 +264,10 @@ function renderGallery(images, total, page) {
         const desc = img.description || img.ocr_text || '';
         const thumb = `/api/images/${img.id}/thumbnail`;
         const dims = (img.width && img.height) ? `${img.width}×${img.height}` : '';
+        const cardId = `card-${img.id}`;
         return `
-        <div class="card" onclick="openImage('${img.id}')">
-            <img class="card-thumb" src="${thumb}" alt="${escHtml(img.filename || '')}" loading="lazy" onerror="this.src='data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 width=%22220%22 height=%22138%22><rect fill=%22%23161b22%22 width=%22220%22 height=%22138%22/><text x=%2250%25%22 y=%2250%25%22 fill=%22%238b949e%22 text-anchor=%22middle%22 dy=%22.3em%22 font-size=%2212%22>Pas d'aperçu</text></svg>'">
+        <div class="card" id="${cardId}" onclick="openImage('${img.id}')">
+            <img class="card-thumb" src="${thumb}" alt="${escHtml(img.filename || '')}" loading="lazy" onerror="var t=document.getElementById('${cardId}').querySelector('.card-thumb');if(t){t.outerHTML='<div class=\\'card-thumb placeholder\\'>🖼️<br><small>Pas d\\'aperçu</small></div>'}">
             <div class="card-body">
                 <div class="card-filename">${escHtml(img.filename || img.id)}</div>
                 <div class="card-meta">
@@ -292,7 +303,7 @@ async function openImage(id) {
         const tags = (img.tags || []).map(t => `<span class="tag">${escHtml(t)}</span>`).join(' ');
         modal.innerHTML = `
             <button class="modal-close" onclick="closeModal()">✕</button>
-            <img src="/api/images/${id}/thumbnail?full=1" alt="${escHtml(img.filename)}" onerror="this.style.display='none'">
+            <img src="/api/images/${id}/thumbnail?full=1" alt="${escHtml(img.filename)}" onerror="this.outerHTML='<div style=\\'aspect-ratio:16/10;background:#161b22;display:flex;align-items:center;justify-content:center;color:#8b949e;border-radius:8px;margin-bottom:16px\\'><span style=\\'font-size:48px\\'>🖼️</span></div>'">
             <div class="modal-details">
                 <h2>${escHtml(img.filename || img.id)}</h2>
                 ${img.description ? `<p class="desc">${escHtml(img.description)}</p>` : ''}