✨ style: update mindmap.css for improved layout and design consistency

static/css/mindmap.css

@@ -360,4 +360,78 @@ body:not(.dark) .mindmap-toolbar button {
 .dark .mindmap-tooltip {
     background: rgba(30, 41, 59, 0.9);
     box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
+}
+
+/* Kategorien-Panel */
+.categories-panel {
+    position: absolute;
+    top: 80px;
+    left: 20px;
+    width: 300px;
+    max-height: calc(100vh - 120px);
+    background: rgba(15, 23, 42, 0.95);
+    border-radius: 12px;
+    padding: 16px;
+    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
+    z-index: 1000;
+    backdrop-filter: blur(10px);
+    border: 1px solid rgba(255, 255, 255, 0.1);
+    transform: translateX(-320px);
+    transition: transform 0.3s ease-in-out;
+    overflow-y: auto;
+}
+
+.categories-panel.visible {
+    transform: translateX(0);
+}
+
+.categories-panel h3 {
+    color: white;
+    font-size: 1.2rem;
+    margin: 0 0 16px 0;
+    padding-bottom: 8px;
+    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
+}
+
+.category-list {
+    list-style: none;
+    padding: 0;
+    margin: 0;
+}
+
+.category-item {
+    display: flex;
+    align-items: center;
+    padding: 8px 12px;
+    margin: 4px 0;
+    border-radius: 6px;
+    cursor: pointer;
+    transition: all 0.2s ease;
+    color: white;
+}
+
+.category-item:hover {
+    background: rgba(255, 255, 255, 0.1);
+    transform: translateX(4px);
+}
+
+.category-color {
+    width: 12px;
+    height: 12px;
+    border-radius: 50%;
+    margin-right: 12px;
+    flex-shrink: 0;
+}
+
+.category-name {
+    flex-grow: 1;
+    font-size: 0.95rem;
+}
+
+.category-count {
+    background: rgba(255, 255, 255, 0.1);
+    padding: 2px 8px;
+    border-radius: 12px;
+    font-size: 0.8rem;
+    margin-left: 8px;
 }