diff --git a/frontend/src/components/common/Modal.tsx b/frontend/src/components/common/Modal.tsx
index 46408139..03d7dd9a 100644
--- a/frontend/src/components/common/Modal.tsx
+++ b/frontend/src/components/common/Modal.tsx
@@ -39,13 +39,13 @@ export function Modal({ isOpen, onClose, title, children, footer, size = 'md' }:
   const sizeClasses = {
     sm: 'max-w-sm',
     md: 'max-w-md',
-    lg: 'max-w-lg',
-    xl: 'max-w-4xl',
+    lg: 'max-w-full sm:max-w-lg',
+    xl: 'max-w-full sm:max-w-4xl',
   }
 
   return (
     <div
-      className="fixed inset-0 z-50 flex items-center justify-center p-4"
+      className="fixed inset-0 z-50 flex items-end justify-center p-0 sm:items-center sm:p-4"
       role="dialog"
       aria-modal="true"
       aria-labelledby="modal-title"
@@ -60,19 +60,21 @@ export function Modal({ isOpen, onClose, title, children, footer, size = 'md' }:
       {/* Modal Content */}
       <div
         className={cn(
-          'relative flex max-h-[85vh] w-full flex-col rounded-lg border border-border bg-card shadow-lg',
+          'relative flex w-full flex-col border border-border bg-card shadow-lg',
+          'max-h-[100vh] rounded-t-lg sm:max-h-[85vh] sm:rounded-lg',
+          'animate-scale-in',
           sizeClasses[size]
         )}
       >
         {/* Header - Fixed at top */}
-        <div className="flex flex-shrink-0 items-center justify-between border-b border-border px-6 py-4">
+        <div className="flex flex-shrink-0 items-center justify-between border-b border-border px-4 py-3 sm:px-6 sm:py-4">
           <h2 id="modal-title" className="text-lg font-semibold text-card-foreground">
             {title}
           </h2>
           <button
             onClick={onClose}
             className={cn(
-              'rounded-md p-1 text-muted-foreground transition-colors',
+              'rounded-md p-1.5 text-muted-foreground transition-colors sm:p-1',
               'hover:bg-accent hover:text-accent-foreground',
               'focus:outline-none focus:ring-2 focus:ring-ring'
             )}
@@ -83,13 +85,13 @@ export function Modal({ isOpen, onClose, title, children, footer, size = 'md' }:
         </div>
 
         {/* Body - Scrollable */}
-        <div className="flex-1 overflow-y-auto px-6 py-4">
+        <div className="flex-1 overflow-y-auto px-4 py-4 sm:px-6">
           {children}
         </div>
 
         {/* Footer - Fixed at bottom */}
         {footer && (
-          <div className="flex-shrink-0 border-t border-border px-6 py-4">
+          <div className="flex-shrink-0 border-t border-border px-4 py-3 sm:px-6 sm:py-4">
             {footer}
           </div>
         )}
diff --git a/frontend/src/components/layout/AppLayout.tsx b/frontend/src/components/layout/AppLayout.tsx
index 8b83b1bd..b543f913 100644
--- a/frontend/src/components/layout/AppLayout.tsx
+++ b/frontend/src/components/layout/AppLayout.tsx
@@ -1,9 +1,11 @@
+import { useState, useEffect, useCallback } from 'react'
 import { Link, useLocation, useNavigate, Outlet } from 'react-router-dom'
 import { useAuthStore } from '@/store/authStore'
 import { usePermissions } from '@/hooks/usePermissions'
 import { ThemeToggle } from '@/components/common/ThemeToggle'
 import { BrandLogo } from '@/components/common/BrandLogo'
 import { BrandWordmark } from '@/components/common/BrandWordmark'
+import { Menu, X } from 'lucide-react'
 import { cn } from '@/lib/utils'
 
 export function AppLayout() {
@@ -11,12 +13,39 @@ export function AppLayout() {
   const navigate = useNavigate()
   const { user, logout } = useAuthStore()
   const { effectiveRole } = usePermissions()
+  const [mobileMenuOpen, setMobileMenuOpen] = useState(false)
 
   const handleLogout = async () => {
+    setMobileMenuOpen(false)
     await logout()
     navigate('/login')
   }
 
+  // Close mobile menu on route change - key-based reset
+  const [prevPath, setPrevPath] = useState(location.pathname)
+  if (prevPath !== location.pathname) {
+    setPrevPath(location.pathname)
+    if (mobileMenuOpen) setMobileMenuOpen(false)
+  }
+
+  // Close on Escape
+  const handleKeyDown = useCallback((e: KeyboardEvent) => {
+    if (e.key === 'Escape') setMobileMenuOpen(false)
+  }, [])
+
+  useEffect(() => {
+    if (mobileMenuOpen) {
+      document.addEventListener('keydown', handleKeyDown)
+      document.body.style.overflow = 'hidden'
+    } else {
+      document.body.style.overflow = ''
+    }
+    return () => {
+      document.removeEventListener('keydown', handleKeyDown)
+      document.body.style.overflow = ''
+    }
+  }, [mobileMenuOpen, handleKeyDown])
+
   const navItems = [
     { path: '/trees', label: 'Trees' },
     { path: '/sessions', label: 'Sessions' },
@@ -29,6 +58,15 @@ export function AppLayout() {
       <header className="sticky top-0 z-50 border-b border-border bg-card backdrop-blur-sm">
         <div className="container mx-auto flex h-16 items-center justify-between px-4">
           <div className="flex items-center gap-8">
+            {/* Mobile hamburger */}
+            <button
+              onClick={() => setMobileMenuOpen(true)}
+              className="rounded-md p-2 text-muted-foreground hover:bg-accent hover:text-accent-foreground sm:hidden"
+              aria-label="Open menu"
+            >
+              <Menu className="h-5 w-5" />
+            </button>
+
             <Link to="/trees" className="flex items-center gap-2">
               <BrandLogo size="sm" />
               <BrandWordmark size="sm" />
@@ -39,7 +77,7 @@ export function AppLayout() {
                   key={item.path}
                   to={item.path}
                   className={cn(
-                    'rounded-md px-3 py-2 text-sm font-medium transition-colors',
+                    'relative rounded-md px-3 py-2 text-sm font-medium transition-colors',
                     location.pathname.startsWith(item.path)
                       ? 'bg-accent text-accent-foreground'
                       : 'text-muted-foreground hover:bg-accent hover:text-accent-foreground'
@@ -73,7 +111,7 @@ export function AppLayout() {
             <button
               onClick={handleLogout}
               className={cn(
-                'rounded-md px-3 py-1.5 text-sm font-medium',
+                'hidden rounded-md px-3 py-1.5 text-sm font-medium sm:block',
                 'text-muted-foreground hover:bg-accent hover:text-accent-foreground'
               )}
             >
@@ -83,8 +121,99 @@ export function AppLayout() {
         </div>
       </header>
 
+      {/* Mobile Nav Drawer */}
+      {mobileMenuOpen && (
+        <div className="fixed inset-0 z-50 sm:hidden">
+          {/* Backdrop */}
+          <div
+            className="absolute inset-0 bg-background/80 backdrop-blur-sm animate-fade-in"
+            onClick={() => setMobileMenuOpen(false)}
+            aria-hidden="true"
+          />
+
+          {/* Drawer */}
+          <nav className="absolute inset-y-0 left-0 w-72 border-r border-border bg-card shadow-xl animate-slide-in-left">
+            <div className="flex h-16 items-center justify-between border-b border-border px-4">
+              <Link to="/trees" className="flex items-center gap-2">
+                <BrandLogo size="sm" />
+                <BrandWordmark size="sm" />
+              </Link>
+              <button
+                onClick={() => setMobileMenuOpen(false)}
+                className="rounded-md p-2 text-muted-foreground hover:bg-accent hover:text-accent-foreground"
+                aria-label="Close menu"
+              >
+                <X className="h-5 w-5" />
+              </button>
+            </div>
+
+            <div className="flex flex-col p-4">
+              {/* User info */}
+              <div className="mb-4 border-b border-border pb-4">
+                <p className="text-sm font-medium text-foreground">
+                  {user?.name || user?.email}
+                </p>
+                {effectiveRole && effectiveRole !== 'engineer' && (
+                  <span
+                    className={cn(
+                      'mt-1 inline-block rounded-full px-2 py-0.5 text-xs font-medium',
+                      effectiveRole === 'super_admin' && 'bg-red-500/10 text-red-600 dark:text-red-400',
+                      effectiveRole === 'team_admin' && 'bg-blue-500/10 text-blue-600 dark:text-blue-400',
+                      effectiveRole === 'viewer' && 'bg-gray-500/10 text-gray-600 dark:text-gray-400'
+                    )}
+                  >
+                    {effectiveRole === 'super_admin' ? 'Super Admin' :
+                     effectiveRole === 'team_admin' ? 'Team Admin' :
+                     'Viewer'}
+                  </span>
+                )}
+              </div>
+
+              {/* Nav items */}
+              <div className="space-y-1">
+                {navItems.map((item) => (
+                  <Link
+                    key={item.path}
+                    to={item.path}
+                    className={cn(
+                      'block rounded-md px-3 py-2.5 text-sm font-medium transition-colors',
+                      location.pathname.startsWith(item.path)
+                        ? 'bg-accent text-accent-foreground'
+                        : 'text-muted-foreground hover:bg-accent hover:text-accent-foreground'
+                    )}
+                  >
+                    {item.label}
+                  </Link>
+                ))}
+              </div>
+
+              {/* Theme toggle */}
+              <div className="mt-4 border-t border-border pt-4">
+                <div className="flex items-center justify-between px-3 py-2">
+                  <span className="text-sm text-muted-foreground">Theme</span>
+                  <ThemeToggle />
+                </div>
+              </div>
+
+              {/* Logout */}
+              <div className="mt-2">
+                <button
+                  onClick={handleLogout}
+                  className={cn(
+                    'w-full rounded-md px-3 py-2.5 text-left text-sm font-medium',
+                    'text-muted-foreground hover:bg-accent hover:text-accent-foreground'
+                  )}
+                >
+                  Logout
+                </button>
+              </div>
+            </div>
+          </nav>
+        </div>
+      )}
+
       {/* Main Content */}
-      <main>
+      <main className="animate-fade-in">
         <Outlet />
       </main>
     </div>
diff --git a/frontend/src/components/library/FolderSidebar.tsx b/frontend/src/components/library/FolderSidebar.tsx
index 41397f04..9e58b2ef 100644
--- a/frontend/src/components/library/FolderSidebar.tsx
+++ b/frontend/src/components/library/FolderSidebar.tsx
@@ -1,5 +1,5 @@
 import { useState, useEffect, useCallback } from 'react'
-import { Folder, ChevronDown, ChevronRight, Plus, MoreVertical, Pencil, Trash2, FolderPlus } from 'lucide-react'
+import { Folder, ChevronDown, ChevronRight, Plus, MoreVertical, Pencil, Trash2, FolderPlus, X } from 'lucide-react'
 import { foldersApi } from '@/api'
 import type { FolderListItem, FolderTreeItem } from '@/types'
 import { cn } from '@/lib/utils'
@@ -9,6 +9,8 @@ interface FolderSidebarProps {
   onFolderSelect: (folderId: string | null) => void
   onCreateFolder: (parentId?: string | null) => void
   onEditFolder: (folder: FolderListItem) => void
+  mobileOpen?: boolean
+  onMobileClose?: () => void
 }
 
 // Build tree structure from flat folder list
@@ -233,6 +235,8 @@ export function FolderSidebar({
   onFolderSelect,
   onCreateFolder,
   onEditFolder,
+  mobileOpen = false,
+  onMobileClose,
 }: FolderSidebarProps) {
   const [folders, setFolders] = useState<FolderListItem[]>([])
   const [folderTree, setFolderTree] = useState<FolderTreeItem[]>([])
@@ -349,8 +353,33 @@ export function FolderSidebar({
 
   return (
     <>
-    <div className="w-56 shrink-0 border-r border-border bg-card">
+    {/* Mobile backdrop */}
+    {mobileOpen && (
+      <div
+        className="fixed inset-0 z-40 bg-background/80 backdrop-blur-sm md:hidden"
+        onClick={onMobileClose}
+        aria-hidden="true"
+      />
+    )}
+    <div className={cn(
+      'w-56 shrink-0 border-r border-border bg-card',
+      'hidden md:block',
+      mobileOpen && 'fixed inset-y-0 left-0 z-50 block animate-slide-in-left md:relative md:animate-none'
+    )}>
       <div className="p-4">
+        {/* Mobile close button */}
+        {mobileOpen && (
+          <div className="mb-3 flex items-center justify-between md:hidden">
+            <span className="text-sm font-medium text-card-foreground">Folders</span>
+            <button
+              onClick={onMobileClose}
+              className="rounded-md p-1.5 text-muted-foreground hover:bg-accent"
+              aria-label="Close folders"
+            >
+              <X className="h-4 w-4" />
+            </button>
+          </div>
+        )}
         <button
           onClick={() => setIsExpanded(!isExpanded)}
           className="flex w-full items-center gap-2 text-sm font-medium text-card-foreground"
diff --git a/frontend/src/components/session/ScratchpadSidebar.tsx b/frontend/src/components/session/ScratchpadSidebar.tsx
index 13270e92..193ba76f 100644
--- a/frontend/src/components/session/ScratchpadSidebar.tsx
+++ b/frontend/src/components/session/ScratchpadSidebar.tsx
@@ -137,12 +137,22 @@ export function ScratchpadSidebar({ sessionId, initialContent, onSave, onOpenCha
         )}
       </button>
 
+      {/* Mobile backdrop */}
+      {!isCollapsed && (
+        <div
+          className="fixed inset-0 z-30 bg-background/80 backdrop-blur-sm sm:hidden"
+          onClick={() => setIsCollapsed(true)}
+          aria-hidden="true"
+        />
+      )}
+
       {/* Panel overlay */}
       <div
         className={cn(
-          'fixed right-2 top-1/2 z-40 -translate-y-1/2',
-          'flex h-[55vh] w-[420px] flex-col',
-          'rounded-lg border border-border bg-card shadow-xl',
+          'fixed z-40',
+          'inset-0 sm:inset-auto sm:right-2 sm:top-1/2 sm:-translate-y-1/2',
+          'flex w-full flex-col sm:h-[55vh] sm:w-[420px]',
+          'border-border bg-card shadow-xl sm:rounded-lg sm:border',
           'transition-transform duration-200 ease-out',
           isCollapsed ? 'translate-x-full' : 'translate-x-0'
         )}
diff --git a/frontend/src/components/step-library/CustomStepModal.tsx b/frontend/src/components/step-library/CustomStepModal.tsx
index fb02a3b5..d1a06e11 100644
--- a/frontend/src/components/step-library/CustomStepModal.tsx
+++ b/frontend/src/components/step-library/CustomStepModal.tsx
@@ -64,14 +64,14 @@ export function CustomStepModal({ isOpen, onClose, onInsertStep }: CustomStepMod
   }
 
   return (
-    <div className="fixed inset-0 z-50 flex items-center justify-center bg-background/80 backdrop-blur-sm">
-      <div className="relative flex h-[90vh] w-full max-w-4xl flex-col rounded-lg border border-border bg-card shadow-lg">
+    <div className="fixed inset-0 z-50 flex items-end justify-center bg-background/80 backdrop-blur-sm sm:items-center sm:p-4">
+      <div className="relative flex h-[95vh] w-full max-w-full flex-col border border-border bg-card shadow-lg sm:h-[90vh] sm:max-w-4xl sm:rounded-lg">
         {/* Header */}
         <div className="flex items-center justify-between border-b border-border p-4">
           <h2 className="text-lg font-semibold">Add Custom Step</h2>
           <button
             onClick={onClose}
-            className="rounded-md p-1 hover:bg-accent"
+            className="rounded-md p-1.5 hover:bg-accent"
             aria-label="Close"
           >
             <X className="h-5 w-5" />
diff --git a/frontend/src/index.css b/frontend/src/index.css
index 733c2d4a..580f7aa4 100644
--- a/frontend/src/index.css
+++ b/frontend/src/index.css
@@ -84,8 +84,59 @@
   }
 }
 
+/* Animations */
+@keyframes fade-in {
+  from { opacity: 0; }
+  to { opacity: 1; }
+}
+
+@keyframes fade-in-up {
+  from { opacity: 0; transform: translateY(4px); }
+  to { opacity: 1; transform: translateY(0); }
+}
+
+@keyframes slide-in-from-left {
+  from { transform: translateX(-100%); }
+  to { transform: translateX(0); }
+}
+
+@keyframes slide-in-from-bottom {
+  from { opacity: 0; transform: translateY(16px); }
+  to { opacity: 1; transform: translateY(0); }
+}
+
+@keyframes scale-in {
+  from { opacity: 0; transform: scale(0.95); }
+  to { opacity: 1; transform: scale(1); }
+}
+
 @layer utilities {
   .text-gradient-brand {
     @apply bg-gradient-brand bg-clip-text text-transparent;
   }
+
+  .animate-fade-in {
+    animation: fade-in 200ms ease-out;
+  }
+
+  .animate-fade-in-up {
+    animation: fade-in-up 200ms ease-out;
+  }
+
+  .animate-slide-in-left {
+    animation: slide-in-from-left 200ms ease-out;
+  }
+
+  .animate-slide-in-bottom {
+    animation: slide-in-from-bottom 200ms ease-out;
+  }
+
+  .animate-scale-in {
+    animation: scale-in 150ms ease-out;
+  }
+
+  /* Button press feedback for primary action buttons */
+  .btn-press {
+    @apply active:scale-[0.98] transition-transform;
+  }
 }
diff --git a/frontend/src/pages/LoginPage.tsx b/frontend/src/pages/LoginPage.tsx
index 90adc8cf..b5def516 100644
--- a/frontend/src/pages/LoginPage.tsx
+++ b/frontend/src/pages/LoginPage.tsx
@@ -38,16 +38,16 @@ export function LoginPage() {
     <div className="flex min-h-screen items-center justify-center bg-background px-4">
       <div className="w-full max-w-md space-y-8">
         <div className="text-center">
-          <div className="mb-6 flex justify-center">
-            <BrandLogo size="lg" />
+          <div className="mb-4 flex justify-center sm:mb-6">
+            <BrandLogo size="lg" className="h-12 w-12 sm:h-16 sm:w-16" />
           </div>
           <h1>
             <BrandWordmark size="lg" />
           </h1>
-          <p className="mt-3 text-lg font-medium text-gradient-brand">
+          <p className="mt-2 text-base font-medium text-gradient-brand sm:mt-3 sm:text-lg">
             Decision Tree Platform
           </p>
-          <p className="mt-2 text-sm text-muted-foreground">
+          <p className="mt-1 text-sm text-muted-foreground sm:mt-2">
             Sign in to your account
           </p>
         </div>
@@ -108,11 +108,11 @@ export function LoginPage() {
               type="submit"
               disabled={isLoading}
               className={cn(
-                'w-full rounded-md px-4 py-2.5 text-sm font-semibold text-white',
+                'w-full rounded-md px-4 py-2.5 text-sm font-semibold text-white btn-press',
                 'bg-gradient-brand hover:bg-gradient-brand-hover',
                 'focus:outline-none focus:ring-2 focus:ring-primary focus:ring-offset-2',
                 'disabled:cursor-not-allowed disabled:opacity-50',
-                'transition-all shadow-lg shadow-primary/20'
+                'shadow-lg shadow-primary/20'
               )}
             >
               {isLoading ? 'Signing in...' : 'Sign in'}
diff --git a/frontend/src/pages/RegisterPage.tsx b/frontend/src/pages/RegisterPage.tsx
index e7ee3ad3..19e50ecd 100644
--- a/frontend/src/pages/RegisterPage.tsx
+++ b/frontend/src/pages/RegisterPage.tsx
@@ -79,16 +79,16 @@ export function RegisterPage() {
     <div className="flex min-h-screen items-center justify-center bg-background px-4">
       <div className="w-full max-w-md space-y-8">
         <div className="text-center">
-          <div className="mb-6 flex justify-center">
-            <BrandLogo size="lg" />
+          <div className="mb-4 flex justify-center sm:mb-6">
+            <BrandLogo size="lg" className="h-12 w-12 sm:h-16 sm:w-16" />
           </div>
           <h1>
             <BrandWordmark size="lg" />
           </h1>
-          <p className="mt-3 text-lg font-medium text-gradient-brand">
+          <p className="mt-2 text-base font-medium text-gradient-brand sm:mt-3 sm:text-lg">
             Decision Tree Platform
           </p>
-          <p className="mt-2 text-sm text-muted-foreground">
+          <p className="mt-1 text-sm text-muted-foreground sm:mt-2">
             Create your account
           </p>
         </div>
@@ -228,11 +228,11 @@ export function RegisterPage() {
               type="submit"
               disabled={isLoading}
               className={cn(
-                'w-full rounded-md px-4 py-2.5 text-sm font-semibold text-white',
+                'w-full rounded-md px-4 py-2.5 text-sm font-semibold text-white btn-press',
                 'bg-gradient-brand hover:bg-gradient-brand-hover',
                 'focus:outline-none focus:ring-2 focus:ring-primary focus:ring-offset-2',
                 'disabled:cursor-not-allowed disabled:opacity-50',
-                'transition-all shadow-lg shadow-primary/20'
+                'shadow-lg shadow-primary/20'
               )}
             >
               {isLoading ? 'Creating account...' : 'Create account'}
diff --git a/frontend/src/pages/SessionDetailPage.tsx b/frontend/src/pages/SessionDetailPage.tsx
index 6de8a37e..cb81efb2 100644
--- a/frontend/src/pages/SessionDetailPage.tsx
+++ b/frontend/src/pages/SessionDetailPage.tsx
@@ -114,7 +114,7 @@ export function SessionDetailPage() {
 
   if (error || !session) {
     return (
-      <div className="container mx-auto px-4 py-8">
+      <div className="container mx-auto px-4 py-6 sm:px-6 sm:py-8">
         <div className="rounded-md bg-destructive/10 p-4 text-destructive">
           {error || 'Session not found'}
         </div>
@@ -129,75 +129,77 @@ export function SessionDetailPage() {
   }
 
   return (
-    <div className="container mx-auto px-4 py-8">
+    <div className="container mx-auto px-4 py-6 sm:px-6 sm:py-8">
       {/* Header */}
-      <div className="mb-8 flex items-start justify-between">
-        <div>
-          <button
-            onClick={() => navigate('/sessions')}
-            className="mb-2 text-sm text-muted-foreground hover:text-foreground"
-          >
-            ← Back to sessions
-          </button>
-          <h1 className="text-3xl font-bold text-foreground">
-            {session.ticket_number || 'Session Details'}
-          </h1>
-          <div className="mt-2 flex items-center gap-4 text-sm text-muted-foreground">
-            <span
-              className={cn(
-                'flex items-center gap-1',
-                session.completed_at ? 'text-green-600' : 'text-yellow-600'
-              )}
+      <div className="mb-8">
+        <div className="flex flex-col gap-4 sm:flex-row sm:items-start sm:justify-between">
+          <div>
+            <button
+              onClick={() => navigate('/sessions')}
+              className="mb-2 text-sm text-muted-foreground hover:text-foreground"
             >
+              ← Back to sessions
+            </button>
+            <h1 className="text-2xl font-bold text-foreground sm:text-3xl">
+              {session.ticket_number || 'Session Details'}
+            </h1>
+            <div className="mt-2 flex items-center gap-4 text-sm text-muted-foreground">
               <span
                 className={cn(
-                  'h-2 w-2 rounded-full',
-                  session.completed_at ? 'bg-green-500' : 'bg-yellow-500'
+                  'flex items-center gap-1',
+                  session.completed_at ? 'text-green-600' : 'text-yellow-600'
                 )}
-              />
-              {session.completed_at ? 'Completed' : 'In Progress'}
-            </span>
-            {session.client_name && <span>Client: {session.client_name}</span>}
+              >
+                <span
+                  className={cn(
+                    'h-2.5 w-2.5 rounded-full',
+                    session.completed_at ? 'bg-green-500' : 'bg-yellow-500'
+                  )}
+                />
+                {session.completed_at ? 'Completed' : 'In Progress'}
+              </span>
+              {session.client_name && <span>Client: {session.client_name}</span>}
+            </div>
           </div>
-        </div>
 
-        {/* Export */}
-        <div className="flex items-center gap-2">
-          <select
-            value={exportFormat}
-            onChange={(e) => setExportFormat(e.target.value as typeof exportFormat)}
-            aria-label="Export format"
-            className={cn(
-              'rounded-md border border-input bg-background px-3 py-2 text-sm',
-              'focus:border-primary focus:outline-none focus:ring-1 focus:ring-primary'
-            )}
-          >
-            <option value="markdown">Markdown</option>
-            <option value="text">Plain Text</option>
-            <option value="html">HTML</option>
-          </select>
-          <button
-            onClick={handleCopy}
-            disabled={isExporting}
-            title="Copy to clipboard"
-            className={cn(
-              'rounded-md border border-input bg-background p-2 text-muted-foreground',
-              'hover:bg-accent hover:text-accent-foreground disabled:opacity-50'
-            )}
-          >
-            {copied ? <Check className="h-4 w-4 text-green-500" /> : <Copy className="h-4 w-4" />}
-          </button>
-          <button
-            onClick={handlePreview}
-            disabled={isExporting}
-            className={cn(
-              'flex items-center gap-2 rounded-md bg-primary px-4 py-2 text-sm font-medium text-primary-foreground',
-              'hover:bg-primary/90 disabled:opacity-50'
-            )}
-          >
-            <Eye className="h-4 w-4" />
-            {isExporting ? 'Loading...' : 'Preview'}
-          </button>
+          {/* Export */}
+          <div className="flex items-center gap-2">
+            <select
+              value={exportFormat}
+              onChange={(e) => setExportFormat(e.target.value as typeof exportFormat)}
+              aria-label="Export format"
+              className={cn(
+                'w-full rounded-md border border-input bg-background px-3 py-2 text-sm sm:w-auto',
+                'focus:border-primary focus:outline-none focus:ring-1 focus:ring-primary'
+              )}
+            >
+              <option value="markdown">Markdown</option>
+              <option value="text">Plain Text</option>
+              <option value="html">HTML</option>
+            </select>
+            <button
+              onClick={handleCopy}
+              disabled={isExporting}
+              title="Copy to clipboard"
+              className={cn(
+                'rounded-md border border-input bg-background p-2 text-muted-foreground',
+                'hover:bg-accent hover:text-accent-foreground disabled:opacity-50'
+              )}
+            >
+              {copied ? <Check className="h-4 w-4 text-green-500" /> : <Copy className="h-4 w-4" />}
+            </button>
+            <button
+              onClick={handlePreview}
+              disabled={isExporting}
+              className={cn(
+                'flex items-center gap-2 rounded-md bg-primary px-4 py-2 text-sm font-medium text-primary-foreground',
+                'hover:bg-primary/90 disabled:opacity-50'
+              )}
+            >
+              <Eye className="h-4 w-4" />
+              {isExporting ? 'Loading...' : 'Preview'}
+            </button>
+          </div>
         </div>
       </div>
 
diff --git a/frontend/src/pages/SessionHistoryPage.tsx b/frontend/src/pages/SessionHistoryPage.tsx
index 2477b517..9e65e1f9 100644
--- a/frontend/src/pages/SessionHistoryPage.tsx
+++ b/frontend/src/pages/SessionHistoryPage.tsx
@@ -35,9 +35,9 @@ export function SessionHistoryPage() {
   }
 
   return (
-    <div className="container mx-auto px-4 py-8">
+    <div className="container mx-auto px-4 py-6 sm:px-6 sm:py-8">
       <div className="mb-8">
-        <h1 className="text-3xl font-bold text-foreground">Session History</h1>
+        <h1 className="text-2xl font-bold text-foreground sm:text-3xl">Session History</h1>
         <p className="mt-2 text-muted-foreground">
           View and manage your troubleshooting sessions
         </p>
@@ -88,14 +88,14 @@ export function SessionHistoryPage() {
           {sessions.map((session) => (
             <div
               key={session.id}
-              className="rounded-lg border border-border bg-card p-4 shadow-sm transition-shadow hover:shadow-md"
+              className="rounded-lg border border-border bg-card p-4 shadow-sm transition-all hover:-translate-y-0.5 hover:border-primary/30 hover:shadow-md"
             >
-              <div className="flex items-start justify-between">
+              <div className="flex flex-col gap-3 sm:flex-row sm:items-start sm:justify-between">
                 <div>
                   <div className="flex items-center gap-2">
                     <span
                       className={cn(
-                        'inline-block h-2 w-2 rounded-full',
+                        'inline-block h-2.5 w-2.5 rounded-full',
                         session.completed_at ? 'bg-green-500' : 'bg-yellow-500'
                       )}
                     />
@@ -122,7 +122,7 @@ export function SessionHistoryPage() {
                   <button
                     onClick={() => navigate(`/sessions/${session.id}`)}
                     className={cn(
-                      'rounded-md border border-input px-3 py-1.5 text-sm font-medium',
+                      'rounded-md border border-input px-3 py-2 text-sm font-medium',
                       'hover:bg-accent hover:text-accent-foreground'
                     )}
                   >
@@ -132,7 +132,7 @@ export function SessionHistoryPage() {
                     <button
                       onClick={() => navigate(`/trees/${session.tree_id}/navigate`, { state: { sessionId: session.id } })}
                       className={cn(
-                        'rounded-md bg-primary px-3 py-1.5 text-sm font-medium text-primary-foreground',
+                        'rounded-md bg-primary px-3 py-2 text-sm font-medium text-primary-foreground',
                         'hover:bg-primary/90'
                       )}
                     >
diff --git a/frontend/src/pages/SettingsPage.tsx b/frontend/src/pages/SettingsPage.tsx
index 68431c1d..60b48c02 100644
--- a/frontend/src/pages/SettingsPage.tsx
+++ b/frontend/src/pages/SettingsPage.tsx
@@ -9,11 +9,11 @@ export function SettingsPage() {
   const { theme } = useThemeStore()
 
   return (
-    <div className="container mx-auto px-4 py-8">
+    <div className="container mx-auto px-4 py-6 sm:px-6 sm:py-8">
       <div className="mb-8">
         <div className="flex items-center gap-3">
           <Settings className="h-8 w-8 text-primary" />
-          <h1 className="text-3xl font-bold text-foreground">Settings</h1>
+          <h1 className="text-2xl font-bold text-foreground sm:text-3xl">Settings</h1>
         </div>
         <p className="mt-2 text-muted-foreground">
           Manage your application preferences
@@ -22,14 +22,14 @@ export function SettingsPage() {
 
       <div className="max-w-2xl space-y-6">
         {/* Appearance Section */}
-        <div className="rounded-lg border border-border bg-card p-6 shadow-sm">
+        <div className="rounded-lg border border-border bg-card p-4 shadow-sm sm:p-6">
           <h2 className="text-lg font-semibold text-card-foreground">Appearance</h2>
           <p className="mt-1 text-sm text-muted-foreground">
             Customize how ResolutionFlow looks on your device
           </p>
 
           <div className="mt-4">
-            <label className="block text-sm font-medium text-card-foreground">
+            <label className="block font-label text-sm font-medium text-card-foreground">
               Theme
             </label>
             <p className="text-sm text-muted-foreground">
@@ -42,7 +42,7 @@ export function SettingsPage() {
         </div>
 
         {/* Export Preferences Section */}
-        <div className="rounded-lg border border-border bg-card p-6 shadow-sm">
+        <div className="rounded-lg border border-border bg-card p-4 shadow-sm sm:p-6">
           <h2 className="text-lg font-semibold text-card-foreground">Export Preferences</h2>
           <p className="mt-1 text-sm text-muted-foreground">
             Configure default settings for session exports
@@ -51,7 +51,7 @@ export function SettingsPage() {
           <div className="mt-4">
             <label
               htmlFor="export-format"
-              className="block text-sm font-medium text-card-foreground"
+              className="block font-label text-sm font-medium text-card-foreground"
             >
               Default Export Format
             </label>
@@ -76,7 +76,7 @@ export function SettingsPage() {
         </div>
 
         {/* About Section */}
-        <div className="rounded-lg border border-border bg-card p-6 shadow-sm">
+        <div className="rounded-lg border border-border bg-card p-4 shadow-sm sm:p-6">
           <h2 className="text-lg font-semibold text-card-foreground">About</h2>
           <p className="mt-1 text-sm text-muted-foreground">
             ResolutionFlow - Decision Tree Platform
diff --git a/frontend/src/pages/TreeEditorPage.tsx b/frontend/src/pages/TreeEditorPage.tsx
index 203d9718..374da3fb 100644
--- a/frontend/src/pages/TreeEditorPage.tsx
+++ b/frontend/src/pages/TreeEditorPage.tsx
@@ -1,7 +1,7 @@
 import { useEffect, useState, useCallback } from 'react'
 import { useParams, useNavigate, useBlocker } from 'react-router-dom'
 import { useStore } from 'zustand'
-import { Undo2, Redo2, Save, CheckCircle2 } from 'lucide-react'
+import { Undo2, Redo2, Save, CheckCircle2, Monitor } from 'lucide-react'
 import { treesApi } from '@/api'
 import type { TreeCreate, TreeUpdate } from '@/types'
 import { useTreeEditorStore, useTreeEditorTemporal } from '@/store/treeEditorStore'
@@ -42,6 +42,15 @@ export function TreeEditorPage() {
   const [showDraftPrompt, setShowDraftPrompt] = useState(false)
   const [saveError, setSaveError] = useState<string | null>(null)
 
+  // Mobile detection
+  const [isMobile, setIsMobile] = useState(false)
+  useEffect(() => {
+    const check = () => setIsMobile(window.innerWidth < 768)
+    check()
+    window.addEventListener('resize', check)
+    return () => window.removeEventListener('resize', check)
+  }, [])
+
   // Calculate if there are blocking errors
   const hasBlockingErrors = validationErrors.some(e => e.severity === 'error')
 
@@ -203,17 +212,30 @@ export function TreeEditorPage() {
     )
   }
 
-  // Mobile warning
-  const isMobile = typeof window !== 'undefined' && window.innerWidth < 768
+  // Mobile gate: show read-only message
+  if (isMobile) {
+    return (
+      <div className="flex h-[calc(100vh-4rem)] flex-col items-center justify-center px-6 text-center">
+        <Monitor className="mb-4 h-12 w-12 text-muted-foreground" />
+        <h2 className="mb-2 text-xl font-semibold text-foreground">Desktop Required</h2>
+        <p className="mb-6 max-w-sm text-sm text-muted-foreground">
+          The tree editor requires a larger screen for the best experience. Please open this page on a desktop or tablet in landscape mode.
+        </p>
+        <button
+          onClick={() => navigate('/trees')}
+          className={cn(
+            'rounded-md bg-primary px-4 py-2 text-sm font-medium text-primary-foreground',
+            'hover:bg-primary/90'
+          )}
+        >
+          Back to Library
+        </button>
+      </div>
+    )
+  }
 
   return (
     <div className="flex h-[calc(100vh-4rem)] flex-col">
-      {/* Mobile Warning */}
-      {isMobile && (
-        <div className="bg-yellow-100 px-4 py-2 text-center text-sm text-yellow-800 dark:bg-yellow-900/20 dark:text-yellow-200">
-          Desktop recommended for tree editing. Viewing mode only on mobile.
-        </div>
-      )}
 
       {/* Draft Restore Prompt */}
       {showDraftPrompt && (
diff --git a/frontend/src/pages/TreeLibraryPage.tsx b/frontend/src/pages/TreeLibraryPage.tsx
index 65dbbb75..8ea63799 100644
--- a/frontend/src/pages/TreeLibraryPage.tsx
+++ b/frontend/src/pages/TreeLibraryPage.tsx
@@ -1,6 +1,6 @@
 import { useEffect, useState, useCallback } from 'react'
 import { useNavigate, Link } from 'react-router-dom'
-import { Plus, Pencil, Globe, Lock, X, Trash2 } from 'lucide-react'
+import { Plus, Pencil, Globe, Lock, X, Trash2, FolderOpen } from 'lucide-react'
 import { treesApi, categoriesApi, foldersApi } from '@/api'
 import type { TreeListItem, CategoryListItem, FolderListItem } from '@/types'
 import { TagBadges } from '@/components/common/TagBadges'
@@ -29,6 +29,9 @@ export function TreeLibraryPage() {
   const [editingFolder, setEditingFolder] = useState<FolderListItem | null>(null)
   const [newFolderParentId, setNewFolderParentId] = useState<string | null>(null)
 
+  // Mobile folder sidebar state
+  const [mobileFolderOpen, setMobileFolderOpen] = useState(false)
+
   // Delete confirmation state
   const [treeToDelete, setTreeToDelete] = useState<TreeListItem | null>(null)
   const [showDeleteConfirm, setShowDeleteConfirm] = useState(false)
@@ -152,17 +155,22 @@ export function TreeLibraryPage() {
       {/* Folder Sidebar */}
       <FolderSidebar
         selectedFolderId={selectedFolderId}
-        onFolderSelect={setSelectedFolderId}
+        onFolderSelect={(id) => {
+          setSelectedFolderId(id)
+          setMobileFolderOpen(false)
+        }}
         onCreateFolder={handleCreateFolder}
         onEditFolder={handleEditFolder}
+        mobileOpen={mobileFolderOpen}
+        onMobileClose={() => setMobileFolderOpen(false)}
       />
 
       {/* Main Content */}
       <div className="flex-1 overflow-auto">
-        <div className="container mx-auto px-4 py-8">
-          <div className="mb-8 flex items-start justify-between">
+        <div className="container mx-auto px-4 py-6 sm:px-6 sm:py-8">
+          <div className="mb-6 flex flex-col gap-4 sm:mb-8 sm:flex-row sm:items-start sm:justify-between">
             <div>
-              <h1 className="text-3xl font-bold text-foreground">Decision Trees</h1>
+              <h1 className="text-2xl font-bold text-foreground sm:text-3xl">Decision Trees</h1>
               <p className="mt-2 text-muted-foreground">
                 Select a troubleshooting tree to start a new session
               </p>
@@ -183,6 +191,18 @@ export function TreeLibraryPage() {
 
           {/* Search and Filter */}
           <div className="mb-4 flex flex-col gap-4 sm:flex-row">
+            {/* Mobile folder button */}
+            <button
+              onClick={() => setMobileFolderOpen(true)}
+              className={cn(
+                'flex items-center gap-2 rounded-md border border-input px-3 py-2 text-sm font-medium md:hidden',
+                'text-muted-foreground hover:bg-accent hover:text-accent-foreground',
+                selectedFolderId && 'border-primary text-primary'
+              )}
+            >
+              <FolderOpen className="h-4 w-4" />
+              Folders
+            </button>
             <div className="flex flex-1 gap-2">
               <input
                 type="text"
@@ -294,7 +314,7 @@ export function TreeLibraryPage() {
               {trees.map((tree) => (
                 <div
                   key={tree.id}
-                  className="rounded-lg border border-border bg-card p-6 shadow-sm transition-shadow hover:shadow-md"
+                  className="rounded-lg border border-border bg-card p-4 shadow-sm transition-all hover:-translate-y-0.5 hover:border-primary/30 hover:shadow-md sm:p-6"
                 >
                   <div className="mb-2 flex items-start justify-between gap-2">
                     <h3 className="font-semibold text-card-foreground">{tree.name}</h3>
@@ -336,7 +356,7 @@ export function TreeLibraryPage() {
                         <Link
                           to={`/trees/${tree.id}/edit`}
                           className={cn(
-                            'rounded-md border border-input p-1.5 text-muted-foreground',
+                            'rounded-md border border-input p-2 text-muted-foreground',
                             'hover:bg-accent hover:text-accent-foreground'
                           )}
                           title="Edit tree"
@@ -364,7 +384,7 @@ export function TreeLibraryPage() {
                         type="button"
                         onClick={() => handleStartSession(tree.id)}
                         className={cn(
-                          'rounded-md bg-primary px-3 py-1.5 text-sm font-medium text-primary-foreground',
+                          'rounded-md bg-primary px-3 py-2 text-sm font-medium text-primary-foreground',
                           'hover:bg-primary/90'
                         )}
                       >
diff --git a/frontend/src/pages/TreeNavigationPage.tsx b/frontend/src/pages/TreeNavigationPage.tsx
index 9ed28883..4773fdac 100644
--- a/frontend/src/pages/TreeNavigationPage.tsx
+++ b/frontend/src/pages/TreeNavigationPage.tsx
@@ -643,7 +643,7 @@ export function TreeNavigationPage() {
   return (
     <div className="h-[calc(100vh-4rem)]">
       {/* Main Content */}
-      <div className={cn('h-full overflow-y-auto px-4 py-8 transition-[padding] duration-200', scratchpadOpen && 'pr-[440px]')}>
+      <div className={cn('h-full overflow-y-auto px-4 py-8 transition-[padding] duration-200', scratchpadOpen && 'sm:pr-[440px]')}>
       <div className="mx-auto max-w-4xl">
       {/* Header */}
       <div className="mb-6 flex items-center justify-between">
@@ -659,7 +659,7 @@ export function TreeNavigationPage() {
         </div>
         <button
           onClick={() => navigate('/sessions')}
-          className="text-sm text-muted-foreground hover:text-foreground"
+          className="rounded-md px-3 py-1.5 text-sm text-muted-foreground hover:bg-accent hover:text-foreground"
         >
           Exit
         </button>
@@ -753,9 +753,10 @@ export function TreeNavigationPage() {
             {/* Add Custom Step Button */}
             <button
               onClick={() => setShowCustomStepModal(true)}
-              className="mt-2 text-sm text-primary hover:underline"
+              className="mt-2 inline-flex items-center gap-1 rounded-md px-2 py-1.5 text-sm text-primary hover:bg-primary/10"
             >
-              + Add Custom Step
+              <Plus className="h-3.5 w-3.5" />
+              Add Custom Step
             </button>
           </>
         )}