Feat: Offline-Funktionalität mit IndexedDB implementiert

static/css/styles.css

@@ -253,4 +253,82 @@ body {
 .search-options .form-check-label {
     cursor: pointer;
     user-select: none;
+}
+
+/* Offline-Indikator */
+.offline-indicator {
+    position: fixed;
+    bottom: 20px;
+    right: 20px;
+    background-color: #ff9800;
+    color: white;
+    padding: 10px 20px;
+    border-radius: 5px;
+    display: flex;
+    align-items: center;
+    gap: 10px;
+    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
+    z-index: 1000;
+}
+
+.offline-icon {
+    font-size: 1.2em;
+}
+
+/* Synchronisations-Status */
+.sync-status {
+    position: fixed;
+    bottom: 20px;
+    right: 20px;
+    background-color: #4CAF50;
+    color: white;
+    padding: 10px 20px;
+    border-radius: 5px;
+    display: flex;
+    align-items: center;
+    gap: 10px;
+    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
+    z-index: 1000;
+}
+
+.sync-icon {
+    font-size: 1.2em;
+    animation: spin 1s linear infinite;
+}
+
+@keyframes spin {
+    from { transform: rotate(0deg); }
+    to { transform: rotate(360deg); }
+}
+
+/* Offline-Modus Styling */
+body.offline {
+    filter: grayscale(20%);
+}
+
+body.offline .search-container {
+    opacity: 0.9;
+}
+
+body.offline .footer::after {
+    content: "Offline-Modus";
+    display: block;
+    text-align: center;
+    color: #ff9800;
+    font-size: 0.8em;
+    margin-top: 5px;
+}
+
+/* Offline-Fallback für Bilder */
+.offline img {
+    opacity: 0.8;
+}
+
+/* Verbesserte Sichtbarkeit im Offline-Modus */
+.offline .search-field input {
+    background-color: rgba(255, 255, 255, 0.9);
+}
+
+.offline .result-count {
+    color: #666;
 }