diff --git a/src/renderer/App.tsx b/src/renderer/App.tsx
index 492cfd0..2ae7b67 100644
--- a/src/renderer/App.tsx
+++ b/src/renderer/App.tsx
@@ -1,5 +1,5 @@
 import React, { useEffect } from 'react';
-import { ActivityBar, Sidebar, Editor, StatusBar, Panel, TabBar, ToastContainer, showToast } from './components';
+import { ActivityBar, Sidebar, Editor, StatusBar, Panel, TabBar, ToastContainer, showToast, ResizablePanel } from './components';
 import { useAppStore, PostData, MediaData, TaskProgress, TabState } from './store';
 import './App.css';
 
@@ -357,11 +357,24 @@ const App: React.FC = () => {
     };
   }, []);
 
+  const { sidebarVisible } = useAppStore();
+
   return (
     <div className="app">
       <div className="app-main">
         <ActivityBar />
-        <Sidebar />
+        {sidebarVisible && (
+          <ResizablePanel
+            direction="horizontal"
+            initialSize={280}
+            minSize={200}
+            maxSize={500}
+            storageKey="sidebar-width"
+            resizerPosition="end"
+          >
+            <Sidebar />
+          </ResizablePanel>
+        )}
         <div className="app-content">
           <TabBar />
           <Editor />
diff --git a/src/renderer/components/ActivityBar/ActivityBar.tsx b/src/renderer/components/ActivityBar/ActivityBar.tsx
index 8c3144d..0758ed8 100644
--- a/src/renderer/components/ActivityBar/ActivityBar.tsx
+++ b/src/renderer/components/ActivityBar/ActivityBar.tsx
@@ -35,7 +35,7 @@ const SyncIcon = () => (
 );
 
 export const ActivityBar: React.FC = () => {
-  const { activeView, setActiveView, syncStatus, pendingChanges, openTab, tabs, activeTabId } = useAppStore();
+  const { activeView, setActiveView, sidebarVisible, toggleSidebar, syncStatus, pendingChanges, openTab, tabs, activeTabId } = useAppStore();
   
   const totalPending = pendingChanges.posts + pendingChanges.media;
   
@@ -45,6 +45,23 @@ export const ActivityBar: React.FC = () => {
   // Check if tags tab is currently active
   const isTagsTabActive = tabs.some(t => t.type === 'tags' && t.id === activeTabId);
 
+  // Handle view click - toggle sidebar if clicking on active view, otherwise switch view
+  const handleViewClick = (view: 'posts' | 'media') => {
+    if (activeView === view && sidebarVisible) {
+      // Clicking on active view toggles sidebar off
+      toggleSidebar();
+    } else if (activeView === view && !sidebarVisible) {
+      // Clicking on active view when hidden shows it
+      toggleSidebar();
+    } else {
+      // Switching to a different view - ensure sidebar is visible
+      if (!sidebarVisible) {
+        toggleSidebar();
+      }
+      setActiveView(view);
+    }
+  };
+
   const handleSettingsClick = () => {
     // Open settings as a dedicated (non-transient) tab
     openTab({ type: 'settings', id: 'settings', isTransient: false });
@@ -59,16 +76,16 @@ export const ActivityBar: React.FC = () => {
     <div className="activity-bar">
       <div className="activity-bar-top">
         <button
-          className={`activity-bar-item ${activeView === 'posts' ? 'active' : ''}`}
-          onClick={() => setActiveView('posts')}
-          title="Posts"
+          className={`activity-bar-item ${activeView === 'posts' && sidebarVisible ? 'active' : ''}`}
+          onClick={() => handleViewClick('posts')}
+          title="Posts (click again to toggle sidebar)"
         >
           <PostsIcon />
         </button>
         <button
-          className={`activity-bar-item ${activeView === 'media' ? 'active' : ''}`}
-          onClick={() => setActiveView('media')}
-          title="Media"
+          className={`activity-bar-item ${activeView === 'media' && sidebarVisible ? 'active' : ''}`}
+          onClick={() => handleViewClick('media')}
+          title="Media (click again to toggle sidebar)"
         >
           <MediaIcon />
         </button>
diff --git a/src/renderer/components/Sidebar/Sidebar.css b/src/renderer/components/Sidebar/Sidebar.css
index 7b2d479..771adb9 100644
--- a/src/renderer/components/Sidebar/Sidebar.css
+++ b/src/renderer/components/Sidebar/Sidebar.css
@@ -1,5 +1,5 @@
 .sidebar {
-  width: 280px;
+  width: 100%;
   height: 100%;
   background-color: var(--vscode-sideBar-background);
   border-right: 1px solid var(--vscode-sideBar-border);
diff --git a/src/renderer/components/TabBar/TabBar.css b/src/renderer/components/TabBar/TabBar.css
index 528e9ca..bd4d4ac 100644
--- a/src/renderer/components/TabBar/TabBar.css
+++ b/src/renderer/components/TabBar/TabBar.css
@@ -45,6 +45,29 @@
   background-color: var(--vscode-toolbar-hoverBackground, rgba(90, 93, 94, 0.31));
 }
 
+/* Sidebar toggle button */
+.tab-bar-toggle-sidebar {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  width: 35px;
+  height: 100%;
+  background-color: transparent;
+  border: none;
+  border-right: 1px solid var(--vscode-tab-border, #252526);
+  color: var(--vscode-icon-foreground, #c5c5c5);
+  cursor: pointer;
+  flex-shrink: 0;
+}
+
+.tab-bar-toggle-sidebar:hover {
+  background-color: var(--vscode-toolbar-hoverBackground, rgba(90, 93, 94, 0.31));
+}
+
+.tab-bar-toggle-sidebar:active {
+  background-color: var(--vscode-toolbar-activeBackground, rgba(99, 102, 103, 0.31));
+}
+
 .tab-scroll-left {
   border-right: 1px solid var(--vscode-tab-border, #252526);
 }
diff --git a/src/renderer/components/TabBar/TabBar.tsx b/src/renderer/components/TabBar/TabBar.tsx
index 84fb56b..87e0fd5 100644
--- a/src/renderer/components/TabBar/TabBar.tsx
+++ b/src/renderer/components/TabBar/TabBar.tsx
@@ -84,6 +84,8 @@ export const TabBar: React.FC = () => {
     posts, 
     media,
     dirtyPosts,
+    sidebarVisible,
+    toggleSidebar,
     setActiveTab, 
     closeTab,
     pinTab,
@@ -138,7 +140,7 @@ export const TabBar: React.FC = () => {
     }
   }, [activeTabId]);
 
-  // Keyboard shortcut handler (Ctrl+W to close active tab)
+  // Keyboard shortcut handler (Ctrl+W to close active tab, Ctrl+B to toggle sidebar)
   useEffect(() => {
     const handleKeyDown = (e: KeyboardEvent) => {
       if ((e.ctrlKey || e.metaKey) && e.key === 'w') {
@@ -147,11 +149,15 @@ export const TabBar: React.FC = () => {
           closeTab(activeTabId);
         }
       }
+      if ((e.ctrlKey || e.metaKey) && e.key === 'b') {
+        e.preventDefault();
+        toggleSidebar();
+      }
     };
 
     window.addEventListener('keydown', handleKeyDown);
     return () => window.removeEventListener('keydown', handleKeyDown);
-  }, [activeTabId, closeTab]);
+  }, [activeTabId, closeTab, toggleSidebar]);
 
   if (tabs.length === 0) {
     return null;
@@ -197,6 +203,18 @@ export const TabBar: React.FC = () => {
 
   return (
     <div className="tab-bar">
+      <button
+        className="tab-bar-toggle-sidebar"
+        onClick={toggleSidebar}
+        title={`${sidebarVisible ? 'Hide' : 'Show'} Sidebar (Ctrl+B)`}
+      >
+        <svg width="16" height="16" viewBox="0 0 16 16" fill="currentColor">
+          <path d="M0 1h16v14H0V1zm1 1v12h4V2H1zm5 0v12h9V2H6z"/>
+          {!sidebarVisible && <path d="M2 4h2v1H2V4zm0 2h2v1H2V6zm0 2h2v1H2V8z" opacity="0.5"/>}
+          {sidebarVisible && <path d="M2 4h2v1H2V4zm0 2h2v1H2V6zm0 2h2v1H2V8z"/>}
+        </svg>
+      </button>
+      
       {showLeftArrow && (
         <button 
           className="tab-scroll-button tab-scroll-left"