cropped & centered Sig icon placeholder in #id_tray_* apparatus

src/static_src/scss/_tray.scss

@@ -147,6 +147,21 @@ $handle-r:         1rem;
     }
 }
 
+.tray-sig-card {
+    padding:  0;
+    overflow: hidden;
+    background: transparent;
+
+    img {
+        display: block;
+        width:  100%;
+        height: 100%;
+        object-fit: cover;
+        object-position: center;
+        transform: scale(1.4);  // crop SVG's internal margins
+    }
+}
+
 @keyframes tray-wobble {
     0%, 100% { transform: translateX(0); }
     20%      { transform: translateX(-8px); }