Fix sidebar scrollbar between nav and content.

Remove independent sidebar scroll so the page scrolls as one unit; add dark themed scrollbars and bump CSS cache versions.

cockpit/static/css/app-sidebar-neo.css

@@ -9,8 +9,11 @@
 .app-sidebar {
   position: sticky;
   top: 0;
-  height: 100vh;
-  overflow-y: auto;
+  align-self: start;
+  height: auto;
+  max-height: none;
+  overflow: visible;
+  overflow-x: hidden;
   padding: 0.75rem 0.6rem;
   background: #080c12;
   border-right: 1px solid rgba(148, 163, 184, 0.1);

cockpit/static/css/mobile.css

@@ -109,6 +109,9 @@ body { overflow-x: hidden; padding-bottom: var(--safe-bottom); }
     padding-top: max(1rem, var(--safe-top));
     flex-direction: column !important;
     flex-wrap: nowrap !important;
+    overflow-y: auto;
+    overflow-x: hidden;
+    -webkit-overflow-scrolling: touch;
   }
   body.nav-open .app-sidebar { transform: translateX(0); }
   body.nav-open { overflow: hidden; }

cockpit/static/css/palantir-theme.css

@@ -25,6 +25,32 @@ a:hover {
   text-decoration: underline;
 }
 
+/* Themed scrollbars (Firefox + WebKit) */
+html {
+  scrollbar-color: rgba(100, 116, 139, 0.5) rgba(8, 12, 18, 0.65);
+  scrollbar-width: thin;
+}
+
+*::-webkit-scrollbar {
+  width: 8px;
+  height: 8px;
+}
+
+*::-webkit-scrollbar-track {
+  background: rgba(8, 12, 18, 0.55);
+}
+
+*::-webkit-scrollbar-thumb {
+  background: rgba(100, 116, 139, 0.45);
+  border-radius: 999px;
+  border: 2px solid rgba(8, 12, 18, 0.55);
+}
+
+*::-webkit-scrollbar-thumb:hover {
+  background: rgba(148, 163, 184, 0.6);
+}
+
+
 .layout {
   display: flex;
   min-height: 100vh;