diff --git a/src/index.html b/src/index.html
index 60a009d..7b1f003 100644
--- a/src/index.html
+++ b/src/index.html
@@ -164,11 +164,12 @@
     .card.multi-dragging { opacity: .3; transform: scale(.96); cursor: grabbing; }
     .card.drag-over { border-color: var(--accent) !important; background: var(--drag-over); }
 
-    /* ── 썸네일: 정사각형 + object-fit: cover ── */
+    /* ── 썸네일: 정사각형 + object-fit: contain ── */
     .card-thumb {
       width: 100%;
       aspect-ratio: 1 / 1;
-      object-fit: cover;
+      object-fit: contain;
+      background: #08080f;
       display: block;
     }
     .card-thumb-placeholder {