style: poprawa kontrastu i widoczności przycisku zamknięcia w panelu ustawień

static/style.css

@@ -963,6 +963,28 @@ body {
     background: rgba(255, 255, 255, 0.02);
 }
 
+#btn-close-settings {
+    width: 42px;
+    height: 42px;
+    background: rgba(255, 255, 255, 0.12);
+    border: 1px solid rgba(255, 255, 255, 0.25);
+    color: #ffffff;
+    border-radius: 12px;
+    transition: var(--transition-smooth);
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    cursor: pointer;
+}
+
+#btn-close-settings:hover {
+    background: rgba(239, 68, 68, 0.25);
+    border-color: rgba(239, 68, 68, 0.6);
+    color: #ff6b6b;
+    transform: scale(1.05);
+    box-shadow: 0 0 12px rgba(239, 68, 68, 0.3);
+}
+
 .modal-body {
     padding: 24px;
     overflow-y: auto;