diff --git a/frontend/app.js b/frontend/app.js
index 0734f78..52b63b0 100644
--- a/frontend/app.js
+++ b/frontend/app.js
@@ -232,6 +232,30 @@
     if (quickSelect) quickSelect.value = selectedContextVault;
   }
 
+  function scrollTreeItemIntoView(element, alignToTop) {
+    if (!element) return;
+    const scrollContainer = document.getElementById("vault-panel-content");
+    if (!scrollContainer) return;
+
+    const containerRect = scrollContainer.getBoundingClientRect();
+    const elementRect = element.getBoundingClientRect();
+    const isAbove = elementRect.top < containerRect.top;
+    const isBelow = elementRect.bottom > containerRect.bottom;
+
+    if (!isAbove && !isBelow && !alignToTop) return;
+
+    const currentTop = scrollContainer.scrollTop;
+    const offsetTop = element.offsetTop;
+    const targetTop = alignToTop
+      ? Math.max(0, offsetTop - 8)
+      : Math.max(0, currentTop + (elementRect.top - containerRect.top) - (containerRect.height * 0.35));
+
+    scrollContainer.scrollTo({
+      top: targetTop,
+      behavior: "smooth",
+    });
+  }
+
   async function refreshSidebarForContext() {
     const container = document.getElementById("vault-tree");
     container.innerHTML = "";
@@ -267,7 +291,7 @@
     if (childContainer && childContainer.classList.contains("collapsed")) {
       await toggleVault(vaultItem, vaultName, true);
     }
-    vaultItem.scrollIntoView({ block: "nearest" });
+    scrollTreeItemIntoView(vaultItem, false);
   }
 
   async function refreshTagsForContext() {
@@ -323,6 +347,8 @@
     const childContainer = document.getElementById(`vault-children-${vaultName}`);
     if (!childContainer) return;
 
+    scrollTreeItemIntoView(itemEl, false);
+
     const shouldExpand = forceExpand || childContainer.classList.contains("collapsed");
 
     if (shouldExpand) {
@@ -364,6 +390,7 @@
         fragment.appendChild(subContainer);
 
         dirItem.addEventListener("click", async () => {
+          scrollTreeItemIntoView(dirItem, false);
           if (subContainer.classList.contains("collapsed")) {
             if (subContainer.children.length === 0) {
               await loadDirectory(vaultName, item.path, subContainer);
@@ -387,6 +414,7 @@
           document.createTextNode(` ${displayName}`),
         ]);
         fileItem.addEventListener("click", () => {
+          scrollTreeItemIntoView(fileItem, false);
           openFile(vaultName, item.path);
           closeMobileSidebar();
         });
@@ -747,6 +775,7 @@
 
   function setPanelExpanded(panelKey, expanded) {
     panelState[panelKey] = expanded;
+    const sidebar = document.getElementById("sidebar");
     const toggle = document.getElementById(`${panelKey}-panel-toggle`);
     const content = document.getElementById(`${panelKey}-panel-content`);
     if (!toggle || !content) return;
@@ -762,6 +791,10 @@
       if (tagSection) tagSection.classList.toggle("collapsed-panel", !expanded);
       if (resizeHandle) resizeHandle.classList.toggle("hidden", !expanded);
     }
+    if (sidebar) {
+      sidebar.classList.toggle("vault-collapsed", !panelState.vault);
+      sidebar.classList.toggle("tag-collapsed", !panelState.tag);
+    }
     safeCreateIcons();
   }
 
diff --git a/frontend/style.css b/frontend/style.css
index 2752eeb..bd0eb6d 100644
--- a/frontend/style.css
+++ b/frontend/style.css
@@ -314,6 +314,17 @@ a:hover {
   flex-shrink: 0;
 }
 
+.sidebar.vault-collapsed .tag-cloud-section {
+  flex: 1 1 auto;
+  min-height: 0;
+  max-height: none;
+}
+
+.sidebar.tag-collapsed .sidebar-tree {
+  flex: 1 1 auto;
+  min-height: 0;
+}
+
 /* --- Sidebar filter --- */
 .sidebar-filter {
   padding: 10px 12px;
@@ -347,9 +358,11 @@ a:hover {
 
 .sidebar-tree {
   flex: 1;
-  overflow-y: auto;
+  overflow: hidden;
   padding: 12px 0;
   min-height: 80px;
+  display: flex;
+  flex-direction: column;
 }
 
 .sidebar-tree::-webkit-scrollbar {
@@ -396,7 +409,29 @@ a:hover {
 }
 
 .sidebar-panel-content.collapsed {
-  display: none;
+  max-height: 0 !important;
+  opacity: 0;
+  overflow: hidden;
+  pointer-events: none;
+}
+
+.sidebar-panel-content {
+  min-height: 0;
+  overflow: hidden;
+  opacity: 1;
+  transition: max-height 340ms ease, opacity 220ms ease;
+}
+
+#vault-panel-content {
+  flex: 1 1 auto;
+  min-height: 0;
+  overflow-y: auto;
+  max-height: 1000px;
+  scroll-behavior: smooth;
+}
+
+#tag-panel-content {
+  max-height: 320px;
 }
 
 .tree-item {
@@ -446,6 +481,7 @@ a:hover {
 
 .tree-children {
   padding-left: 16px;
+  overflow: hidden;
 }
 
 .tree-children.collapsed {
@@ -476,14 +512,18 @@ a:hover {
   height: 180px;
   min-height: 60px;
   max-height: 400px;
-  overflow-y: auto;
+  overflow: hidden;
   flex-shrink: 0;
+  display: flex;
+  flex-direction: column;
+  transition: height 340ms ease, min-height 340ms ease, max-height 340ms ease, flex 340ms ease;
 }
 .tag-cloud-section.collapsed-panel {
   height: auto;
   min-height: 0;
   max-height: none;
   overflow: hidden;
+  flex: 0 0 auto;
 }
 .tag-cloud-section::-webkit-scrollbar {
   width: 6px;
@@ -510,6 +550,11 @@ a:hover {
   padding: 0 16px 12px;
 }
 
+.tag-cloud-section:not(.collapsed-panel) #tag-panel-content {
+  overflow-y: auto;
+  flex: 1 1 auto;
+}
+
 .tag-item {
   display: inline-block;
   padding: 2px 8px;
@@ -1281,6 +1326,14 @@ body.resizing-v {
     min-height: 80px;
   }
 
+  #vault-panel-content {
+    max-height: none;
+  }
+
+  #tag-panel-content {
+    max-height: none;
+  }
+
    .help-content {
      padding: 20px 16px 28px;
    }