diff --git a/public/theme.js b/public/theme.js
new file mode 100644
index 0000000..9d1c19e
--- /dev/null
+++ b/public/theme.js
@@ -0,0 +1,30 @@
+// Immediately apply the theme before any content loads
+(function() {
+  try {
+    let theme = localStorage.getItem('theme') || 'system';
+    const systemTheme = window.matchMedia('(prefers-color-scheme: dark)').matches;
+    
+    // If theme is system, use the system preference
+    if (theme === 'system') {
+      theme = systemTheme ? 'dark' : 'light';
+    }
+
+    // Remove both classes and add the current one
+    document.documentElement.classList.remove('light', 'dark');
+    document.documentElement.classList.add(theme);
+    document.documentElement.style.colorScheme = theme;
+
+    // Watch for system theme changes
+    window.matchMedia('(prefers-color-scheme: dark)').addEventListener('change', (e) => {
+      if (localStorage.getItem('theme') === 'system') {
+        document.documentElement.classList.remove('light', 'dark');
+        document.documentElement.classList.add(e.matches ? 'dark' : 'light');
+        document.documentElement.style.colorScheme = e.matches ? 'dark' : 'light';
+      }
+    });
+  } catch (e) {
+    // Fallback to light theme if localStorage is not available
+    document.documentElement.classList.add('light');
+    document.documentElement.style.colorScheme = 'light';
+  }
+})();
diff --git a/src/app/globals.css b/src/app/globals.css
index 697735e..08d34f2 100644
--- a/src/app/globals.css
+++ b/src/app/globals.css
@@ -2,7 +2,8 @@
 @tailwind components;
 @tailwind utilities;
 
-:root {
+:root,
+html.light {
   --background: #ffffff;
   --foreground: #171717;
   --base: #f5f5f5;
@@ -11,19 +12,26 @@
   --muted: #737373;
 }
 
-@media (prefers-color-scheme: dark) {
-  :root {
-    --background: #0a0a0a;
-    --foreground: #ededed;
-    --base: #333333;
-    --offbase: #4a4a4a;
-    --accent: #f87171;
-    --muted: #a3a3a3;
-  }
+html.dark {
+  --background: #111111;
+  --foreground: #ededed;
+  --base: #1f1f1f;
+  --offbase: #4a4a4a;
+  --accent: #f87171;
+  --muted: #a3a3a3;
+}
+
+/* Ensure background color is set before content loads */
+html {
+  background-color: var(--background);
 }
 
 body {
   color: var(--foreground);
   background: var(--background);
-  font-family: Arial, Helvetica, sans-serif;
+  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", "Oxygen",
+    "Ubuntu", "Cantarell", "Fira Sans", "Droid Sans", "Helvetica Neue",
+    sans-serif;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
 }
diff --git a/src/app/layout.tsx b/src/app/layout.tsx
index d200d6c..1d65e58 100644
--- a/src/app/layout.tsx
+++ b/src/app/layout.tsx
@@ -1,22 +1,11 @@
-import type { Metadata } from "next";
-import { Geist, Geist_Mono } from "next/font/google";
 import "./globals.css";
 import { Providers } from "./providers";
 import TTSPlayer from "@/components/TTSPlayer";
-
-const geistSans = Geist({
-  variable: "--font-geist-sans",
-  subsets: ["latin"],
-});
-
-const geistMono = Geist_Mono({
-  variable: "--font-geist-mono",
-  subsets: ["latin"],
-});
+import { Metadata } from "next";
 
 export const metadata: Metadata = {
-  title: "Create Next App",
-  description: "Generated by create next app",
+  title: "OpenReader WebUI",
+  description: "A modern web interface for reading and managing documents",
 };
 
 export default function RootLayout({
@@ -25,10 +14,18 @@ export default function RootLayout({
   children: React.ReactNode;
 }) {
   return (
-    <html lang="en">
-      <body
-        className={`${geistSans.variable} ${geistMono.variable} font-sans antialiased`}
-      >
+    <html lang="en" suppressHydrationWarning>
+      <head>
+        <meta name="color-scheme" content="light dark" />
+        <script src="/theme.js" />
+        <style dangerouslySetInnerHTML={{ __html: `
+          :root { color-scheme: light dark; }
+          html.dark { color-scheme: dark; }
+          html.light { color-scheme: light; }
+          html { background: var(--background); }
+        `}} />
+      </head>
+      <body className="antialiased">
         <Providers>
           <div className="min-h-screen bg-background p-4">
             <div className="max-w-6xl mx-auto align-center">
diff --git a/src/app/page.tsx b/src/app/page.tsx
index 6c78312..7f2e3f5 100644
--- a/src/app/page.tsx
+++ b/src/app/page.tsx
@@ -1,16 +1,49 @@
 'use client';
 
+import { useState } from 'react';
 import { PDFUploader } from '@/components/PDFUploader';
 import { DocumentList } from '@/components/DocumentList';
+import { SettingsModal } from '@/components/SettingsModal';
 
 export default function Home() {
+  const [isSettingsOpen, setIsSettingsOpen] = useState(false);
+
   return (
     <div className='p-4'>
-      <h1 className="text-2xl font-bold mb-6 text-center">OpenReader WebUI</h1>
+      <div className="flex justify-between items-center mb-6">
+        <h1 className="text-2xl font-bold text-center flex-grow">OpenReader WebUI</h1>
+        <button
+          onClick={() => setIsSettingsOpen(true)}
+          className="rounded-full p-2.5 text-foreground hover:bg-base focus:bg-base 
+                   focus:outline-none focus:ring-2 focus:ring-accent transition-colors"
+          aria-label="Settings"
+        >
+          <svg
+            xmlns="http://www.w3.org/2000/svg"
+            fill="none"
+            viewBox="0 0 24 24"
+            strokeWidth={1.5}
+            stroke="currentColor"
+            className="w-6 h-6 hover:animate-spin-slow"
+          >
+            <path
+              strokeLinecap="round"
+              strokeLinejoin="round"
+              d="M9.594 3.94c.09-.542.56-.94 1.11-.94h2.593c.55 0 1.02.398 1.11.94l.213 1.281c.063.374.313.686.645.87.074.04.147.083.22.127.324.196.72.257 1.075.124l1.217-.456a1.125 1.125 0 011.37.49l1.296 2.247a1.125 1.125 0 01-.26 1.431l-1.003.827c-.293.24-.438.613-.431.992a6.759 6.759 0 010 .255c-.007.378.138.75.43.99l1.005.828c.424.35.534.954.26 1.43l-1.298 2.247a1.125 1.125 0 01-1.369.491l-1.217-.456c-.355-.133-.75-.072-1.076.124a6.57 6.57 0 01-.22.128c-.331.183-.581.495-.644.869l-.213 1.28c-.09.543-.56.941-1.11.941h-2.594c-.55 0-1.02-.398-1.11-.94l-.213-1.281c-.062-.374-.312-.686-.644-.87a6.52 6.52 0 01-.22-.127c-.325-.196-.72-.257-1.076-.124l-1.217.456a1.125 1.125 0 01-1.369-.49l-1.297-2.247a1.125 1.125 0 01.26-1.431l1.004-.827c.292-.24.437-.613.43-.992a6.932 6.932 0 010-.255c.007-.378-.138-.75-.43-.99l-1.004-.828a1.125 1.125 0 01-.26-1.43l1.297-2.247a1.125 1.125 0 011.37-.491l1.216.456c.356.133.751.072 1.076-.124.072-.044.146-.087.22-.128.332-.183.582-.495.644-.869l.214-1.281z"
+            />
+            <path
+              strokeLinecap="round"
+              strokeLinejoin="round"
+              d="M15 12a3 3 0 11-6 0 3 3 0 016 0z"
+            />
+          </svg>
+        </button>
+      </div>
       <div className="flex flex-col items-center gap-6">
         <PDFUploader className="w-full max-w-md" />
         <DocumentList />
       </div>
+      <SettingsModal isOpen={isSettingsOpen} setIsOpen={setIsSettingsOpen} />
     </div>
   );
 }
diff --git a/src/app/providers.tsx b/src/app/providers.tsx
index 91b3742..f80f018 100644
--- a/src/app/providers.tsx
+++ b/src/app/providers.tsx
@@ -2,14 +2,17 @@
 
 import { PDFProvider } from '@/context/PDFContext';
 import { TTSProvider } from '@/context/TTSContext';
+import { ThemeProvider } from '@/context/ThemeContext';
 import { ReactNode } from 'react';
 
 export function Providers({ children }: { children: ReactNode }) {
   return (
-    <TTSProvider>
-      <PDFProvider>
-        {children}
-      </PDFProvider>
-    </TTSProvider>
+    <ThemeProvider>
+      <TTSProvider>
+        <PDFProvider>
+          {children}
+        </PDFProvider>
+      </TTSProvider>
+    </ThemeProvider>
   );
 }
diff --git a/src/components/DocumentList.tsx b/src/components/DocumentList.tsx
index 564b15a..1b309a1 100644
--- a/src/components/DocumentList.tsx
+++ b/src/components/DocumentList.tsx
@@ -1,8 +1,25 @@
 import { usePDF } from '@/context/PDFContext';
 import Link from 'next/link';
+import { Dialog } from '@headlessui/react';
+import { Transition } from '@headlessui/react';
+import { Fragment, useState } from 'react';
 
 export function DocumentList() {
   const { documents, removeDocument, isLoading, error } = usePDF();
+  const [isDeleteDialogOpen, setIsDeleteDialogOpen] = useState(false);
+  const [documentToDelete, setDocumentToDelete] = useState<{ id: string; name: string } | null>(null);
+
+  const handleDelete = async () => {
+    if (documentToDelete) {
+      try {
+        await removeDocument(documentToDelete.id);
+        setIsDeleteDialogOpen(false);
+        setDocumentToDelete(null);
+      } catch (err) {
+        console.error('Failed to remove document:', err);
+      }
+    }
+  };
 
   if (isLoading) {
     return (
@@ -33,44 +50,116 @@ export function DocumentList() {
       <h2 className="text-xl font-semibold mb-4 text-foreground">Your Documents</h2>
       <div className="bg-background rounded-lg shadow p-2 space-y-2">
         {documents.map((doc) => (
-          <div 
+          <Transition
             key={doc.id}
-            className="flex items-center justify-between hover:bg-base p-2 rounded-lg transition-colors"
+            show={true}
+            enter="transition duration-100 ease-out"
+            enterFrom="transform scale-95 opacity-0"
+            enterTo="transform scale-100 opacity-100"
+            leave="transition duration-75 ease-out"
+            leaveFrom="transform scale-100 opacity-100"
+            leaveTo="transform scale-95 opacity-0"
           >
-            <Link 
-              href={`/pdf/${encodeURIComponent(doc.id)}`}
-              className="flex items-center space-x-4 flex-1 min-w-0"
+            <div 
+              className="flex items-center justify-between hover:bg-base p-2 rounded-lg transition-colors"
             >
-              <div className="flex-shrink-0">
-                <svg className="w-8 h-8 text-accent" fill="none" stroke="currentColor" viewBox="0 0 24 24">
-                  <path strokeLinecap="round" strokeLinejoin="round" strokeWidth="2" d="M7 21h10a2 2 0 002-2V9.414a1 1 0 00-.293-.707l-5.414-5.414A1 1 0 0012.586 3H7a2 2 0 00-2 2v14a2 2 0 002 2z" />
+              <Link 
+                href={`/pdf/${encodeURIComponent(doc.id)}`}
+                className="flex items-center space-x-4 flex-1 min-w-0"
+              >
+                <div className="flex-shrink-0">
+                  <svg className="w-8 h-8 text-accent" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth="2" d="M7 21h10a2 2 0 002-2V9.414a1 1 0 00-.293-.707l-5.414-5.414A1 1 0 0012.586 3H7a2 2 0 00-2 2v14a2 2 0 002 2z" />
+                  </svg>
+                </div>
+                <div className="flex-1 min-w-0">
+                  <p className="text-foreground font-medium truncate">{doc.name}</p>
+                  <p className="text-sm text-muted truncate">
+                    {(doc.size / 1024 / 1024).toFixed(2)} MB
+                  </p>
+                </div>
+              </Link>
+              <button
+                onClick={() => {
+                  setDocumentToDelete({ id: doc.id, name: doc.name });
+                  setIsDeleteDialogOpen(true);
+                }}
+                className="ml-4 p-2 text-muted hover:text-red-500 rounded-lg hover:bg-red-50 transition-colors"
+                aria-label="Delete document"
+              >
+                <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                  <path strokeLinecap="round" strokeLinejoin="round" strokeWidth="2" d="M19 7l-.867 12.142A2 2 0 0116.138 21H7.862a2 2 0 01-1.995-1.858L5 7m5 4v6m4-6v6m1-10V4a1 1 0 00-1-1h-4a1 1 0 00-1 1v3M4 7h16" />
                 </svg>
-              </div>
-              <div className="flex-1 min-w-0">
-                <p className="text-foreground font-medium truncate">{doc.name}</p>
-                <p className="text-sm text-muted truncate">
-                  {(doc.size / 1024 / 1024).toFixed(2)} MB
-                </p>
-              </div>
-            </Link>
-            <button
-              onClick={async () => {
-                try {
-                  await removeDocument(doc.id);
-                } catch (err) {
-                  console.error('Failed to remove document:', err);
-                }
-              }}
-              className="ml-4 p-2 text-muted hover:text-red-500 rounded-lg hover:bg-red-50 transition-colors"
-              aria-label="Delete document"
-            >
-              <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
-                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth="2" d="M19 7l-.867 12.142A2 2 0 0116.138 21H7.862a2 2 0 01-1.995-1.858L5 7m5 4v6m4-6v6m1-10V4a1 1 0 00-1-1h-4a1 1 0 00-1 1v3M4 7h16" />
-              </svg>
-            </button>
-          </div>
+              </button>
+            </div>
+          </Transition>
         ))}
       </div>
+
+      <Transition appear show={isDeleteDialogOpen} as={Fragment}>
+        <Dialog
+          as="div"
+          className="relative z-50"
+          onClose={() => setIsDeleteDialogOpen(false)}
+        >
+          <Transition.Child
+            as={Fragment}
+            enter="ease-out duration-300"
+            enterFrom="opacity-0"
+            enterTo="opacity-100"
+            leave="ease-in duration-200"
+            leaveFrom="opacity-100"
+            leaveTo="opacity-0"
+          >
+            <div className="fixed inset-0 bg-black bg-opacity-25" />
+          </Transition.Child>
+
+          <div className="fixed inset-0 overflow-y-auto">
+            <div className="flex min-h-full items-center justify-center p-4 text-center">
+              <Transition.Child
+                as={Fragment}
+                enter="ease-out duration-300"
+                enterFrom="opacity-0 scale-95"
+                enterTo="opacity-100 scale-100"
+                leave="ease-in duration-200"
+                leaveFrom="opacity-100 scale-100"
+                leaveTo="opacity-0 scale-95"
+              >
+                <Dialog.Panel className="w-full max-w-md transform overflow-hidden rounded-2xl bg-background p-6 text-left align-middle shadow-xl transition-all">
+                  <Dialog.Title
+                    as="h3"
+                    className="text-lg font-medium leading-6 text-foreground"
+                  >
+                    Delete Document
+                  </Dialog.Title>
+                  <div className="mt-2">
+                    <p className="text-sm text-muted">
+                      Are you sure you want to delete "{documentToDelete?.name}"? This action cannot be undone.
+                    </p>
+                  </div>
+
+                  <div className="mt-4 flex justify-end space-x-3">
+                    <button
+                      type="button"
+                      className="inline-flex justify-center rounded-md border border-transparent bg-base px-4 py-2 text-sm font-medium text-foreground hover:bg-base/80 focus:outline-none focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2"
+                      onClick={() => setIsDeleteDialogOpen(false)}
+                    >
+                      Cancel
+                    </button>
+                    <button
+                      type="button"
+                      className="inline-flex justify-center rounded-md border border-transparent bg-red-600 px-4 py-2 text-sm font-medium text-white hover:bg-red-700 focus:outline-none focus-visible:ring-2 focus-visible:ring-red-500 focus-visible:ring-offset-2"
+                      onClick={handleDelete}
+                    >
+                      Delete
+                    </button>
+                  </div>
+                </Dialog.Panel>
+              </Transition.Child>
+            </div>
+          </div>
+        </Dialog>
+      </Transition>
     </div>
   );
 }
diff --git a/src/components/PDFViewer.tsx b/src/components/PDFViewer.tsx
index 223afe8..f070aa0 100644
--- a/src/components/PDFViewer.tsx
+++ b/src/components/PDFViewer.tsx
@@ -244,7 +244,7 @@ export function PDFViewer({ pdfData }: PDFViewerProps) {
       });
       
       bestMatch.elements.forEach(element => {
-        element.style.backgroundColor = 'yellow';
+        element.style.backgroundColor = 'grey';
         element.style.opacity = '0.4';
       });
 
diff --git a/src/components/SettingsModal.tsx b/src/components/SettingsModal.tsx
new file mode 100644
index 0000000..17fa84b
--- /dev/null
+++ b/src/components/SettingsModal.tsx
@@ -0,0 +1,147 @@
+'use client';
+
+import { Fragment } from 'react';
+import { Dialog, Transition, Listbox } from '@headlessui/react';
+import { useTheme } from '@/context/ThemeContext';
+
+interface SettingsModalProps {
+  isOpen: boolean;
+  setIsOpen: (isOpen: boolean) => void;
+}
+
+const themes = [
+  { id: 'light' as const, name: 'Light' },
+  { id: 'dark' as const, name: 'Dark' },
+  { id: 'system' as const, name: 'System' },
+];
+
+export function SettingsModal({ isOpen, setIsOpen }: SettingsModalProps) {
+  const { theme, setTheme } = useTheme();
+  const selectedTheme = themes.find(t => t.id === theme) || themes[0];
+
+  return (
+    <Transition appear show={isOpen} as={Fragment}>
+      <Dialog as="div" className="relative z-50" onClose={() => setIsOpen(false)}>
+        <Transition.Child
+          as={Fragment}
+          enter="ease-out duration-300"
+          enterFrom="opacity-0"
+          enterTo="opacity-100"
+          leave="ease-in duration-200"
+          leaveFrom="opacity-100"
+          leaveTo="opacity-0"
+        >
+          <div className="fixed inset-0 bg-black/25 backdrop-blur-sm" />
+        </Transition.Child>
+
+        <div className="fixed inset-0 overflow-y-auto">
+          <div className="flex min-h-full items-center justify-center p-4 text-center">
+            <Transition.Child
+              as={Fragment}
+              enter="ease-out duration-300"
+              enterFrom="opacity-0 scale-95"
+              enterTo="opacity-100 scale-100"
+              leave="ease-in duration-200"
+              leaveFrom="opacity-100 scale-100"
+              leaveTo="opacity-0 scale-95"
+            >
+              <Dialog.Panel className="w-full max-w-md transform rounded-2xl bg-base p-6 text-left align-middle shadow-xl transition-all">
+                <Dialog.Title
+                  as="h3"
+                  className="text-lg font-semibold leading-6 text-foreground"
+                >
+                  Settings
+                </Dialog.Title>
+                <div className="mt-4">
+                  <div className="space-y-4">
+                    <div className="space-y-2">
+                      <label className="block text-sm font-medium text-foreground">Theme</label>
+                      <Listbox value={selectedTheme} onChange={(newTheme) => setTheme(newTheme.id)}>
+                        <div className="relative">
+                          <Listbox.Button className="relative w-full cursor-pointer rounded-lg bg-background py-2 pl-3 pr-10 text-left text-foreground shadow-sm focus:outline-none focus:ring-2 focus:ring-accent">
+                            <span className="block truncate">{selectedTheme.name}</span>
+                            <span className="pointer-events-none absolute inset-y-0 right-0 flex items-center pr-2">
+                              <svg 
+                                xmlns="http://www.w3.org/2000/svg" 
+                                className="h-5 w-5 text-muted" 
+                                viewBox="0 0 20 20" 
+                                fill="currentColor"
+                              >
+                                <path 
+                                  fillRule="evenodd" 
+                                  d="M10 3a1 1 0 01.707.293l3 3a1 1 0 01-1.414 1.414L10 5.414 7.707 7.707a1 1 0 01-1.414-1.414l3-3A1 1 0 0110 3zm-3.707 9.293a1 1 0 011.414 0L10 14.586l2.293-2.293a1 1 0 011.414 1.414l-3 3a1 1 0 01-1.414 0l-3-3a1 1 0 010-1.414z" 
+                                  clipRule="evenodd" 
+                                />
+                              </svg>
+                            </span>
+                          </Listbox.Button>
+                          <Transition
+                            as={Fragment}
+                            leave="transition ease-in duration-100"
+                            leaveFrom="opacity-100"
+                            leaveTo="opacity-0"
+                          >
+                            <Listbox.Options className="absolute mt-1 max-h-60 w-full overflow-auto rounded-md bg-background py-1 shadow-lg ring-1 ring-black/5 focus:outline-none">
+                              {themes.map((theme) => (
+                                <Listbox.Option
+                                  key={theme.id}
+                                  className={({ active }) =>
+                                    `relative cursor-pointer select-none py-2 pl-10 pr-4 ${
+                                      active ? 'bg-accent/10 text-accent' : 'text-foreground'
+                                    }`
+                                  }
+                                  value={theme}
+                                >
+                                  {({ selected }) => (
+                                    <>
+                                      <span className={`block truncate ${selected ? 'font-medium' : 'font-normal'}`}>
+                                        {theme.name}
+                                      </span>
+                                      {selected ? (
+                                        <span className="absolute inset-y-0 left-0 flex items-center pl-3 text-accent">
+                                          <svg 
+                                            xmlns="http://www.w3.org/2000/svg" 
+                                            className="h-5 w-5" 
+                                            viewBox="0 0 20 20" 
+                                            fill="currentColor"
+                                          >
+                                            <path 
+                                              fillRule="evenodd" 
+                                              d="M16.707 5.293a1 1 0 010 1.414l-8 8a1 1 0 01-1.414 0l-4-4a1 1 0 011.414-1.414L8 12.586l7.293-7.293a1 1 0 011.414 0z" 
+                                              clipRule="evenodd" 
+                                            />
+                                          </svg>
+                                        </span>
+                                      ) : null}
+                                    </>
+                                  )}
+                                </Listbox.Option>
+                              ))}
+                            </Listbox.Options>
+                          </Transition>
+                        </div>
+                      </Listbox>
+                    </div>
+                  </div>
+                </div>
+
+                <div className="mt-6 flex justify-end">
+                  <button
+                    type="button"
+                    className="inline-flex justify-center rounded-lg bg-accent px-4 py-2 text-sm 
+                             font-medium text-white hover:bg-accent/90 focus:outline-none 
+                             focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2
+                             transition-colors"
+                    onClick={() => setIsOpen(false)}
+                  >
+                    Close
+                  </button>
+                </div>
+              </Dialog.Panel>
+            </Transition.Child>
+          </div>
+        </div>
+      </Dialog>
+    </Transition>
+  );
+}
diff --git a/src/components/TTSPlayer.tsx b/src/components/TTSPlayer.tsx
index b06ece7..61c41ad 100644
--- a/src/components/TTSPlayer.tsx
+++ b/src/components/TTSPlayer.tsx
@@ -10,9 +10,18 @@ import {
   SkipBackwardIcon,
 } from './icons/Icons';
 
+// Loading spinner component
+function LoadingSpinner() {
+  return (
+    <div className="absolute inset-0 flex items-center justify-center">
+      <div className="animate-spin h-4 w-4 border-2 border-foreground border-t-transparent rounded-full" />
+    </div>
+  );
+}
+
 export default function TTSPlayer() {
   const [isVisible, setIsVisible] = useState(true);
-  const { isPlaying, togglePlay, skipForward, skipBackward } = useTTS();
+  const { isPlaying, togglePlay, skipForward, skipBackward, isProcessing } = useTTS();
 
   return (
     <div 
@@ -23,10 +32,11 @@ export default function TTSPlayer() {
       <div className="bg-base dark:bg-base rounded-full shadow-lg px-2 py-1 flex items-center space-x-2 relative">
         <Button
           onClick={skipBackward}
-          className="relative p-2 rounded-full text-foreground hover:bg-offbase data-[hover]:bg-offbase data-[active]:bg-offbase/80 transition-colors duration-200 focus:outline-none"
+          className="relative p-2 rounded-full text-foreground hover:bg-offbase data-[hover]:bg-offbase data-[active]:bg-offbase/80 transition-colors duration-200 focus:outline-none disabled:opacity-50"
           aria-label="Skip backward"
+          disabled={isProcessing}
         >
-          <SkipBackwardIcon />
+          {isProcessing ? <LoadingSpinner /> : <SkipBackwardIcon />}
         </Button>
         
         <Button
@@ -39,10 +49,11 @@ export default function TTSPlayer() {
 
         <Button
           onClick={skipForward}
-          className="relative p-2 rounded-full text-foreground hover:bg-offbase data-[hover]:bg-offbase data-[active]:bg-offbase/80 transition-colors duration-200 focus:outline-none"
+          className="relative p-2 rounded-full text-foreground hover:bg-offbase data-[hover]:bg-offbase data-[active]:bg-offbase/80 transition-colors duration-200 focus:outline-none disabled:opacity-50"
           aria-label="Skip forward"
+          disabled={isProcessing}
         >
-          <SkipForwardIcon />
+          {isProcessing ? <LoadingSpinner /> : <SkipForwardIcon />}
         </Button>
       </div>
     </div>
diff --git a/src/context/TTSContext.tsx b/src/context/TTSContext.tsx
index 331489a..f9766a1 100644
--- a/src/context/TTSContext.tsx
+++ b/src/context/TTSContext.tsx
@@ -37,6 +37,7 @@ interface TTSContextType {
   setCurrentIndex: (index: number) => void;
   stopAndPlayFromIndex: (index: number) => void;
   sentences: string[];
+  isProcessing: boolean;
 }
 
 const TTSContext = createContext<TTSContextType | undefined>(undefined);
@@ -123,9 +124,14 @@ export function TTSProvider({ children }: { children: React.ReactNode }) {
 
   const processAndPlaySentence = async (sentence: string) => {
     if (!audioContext || isProcessing) return;
-    setIsProcessing(true);
 
     try {
+      // Only set processing if we need to fetch from API
+      const cleanedSentence = preprocessText(sentence);
+      if (!audioCacheRef.current.has(cleanedSentence)) {
+        setIsProcessing(true);
+      }
+
       // Cancel any existing request
       if (currentRequestRef.current) {
         currentRequestRef.current.abort();
@@ -140,8 +146,6 @@ export function TTSProvider({ children }: { children: React.ReactNode }) {
         setActiveSource(null);
       }
 
-      // Clean the sentence before processing
-      const cleanedSentence = preprocessText(sentence);
       let audioBuffer = audioCacheRef.current.get(cleanedSentence);
 
       if (!audioBuffer) {
@@ -161,9 +165,10 @@ export function TTSProvider({ children }: { children: React.ReactNode }) {
 
         // Store in cache
         audioCacheRef.current.set(cleanedSentence, audioBuffer);
+        setIsProcessing(false);
       }
 
-      // If the request was aborted, do not proceed
+      // If the request was aborted or component unmounted, do not proceed
       if (!currentRequestRef.current) return;
 
       const source = audioContext.createBufferSource();
@@ -174,7 +179,6 @@ export function TTSProvider({ children }: { children: React.ReactNode }) {
       // Set up onended handler before starting
       source.onended = () => {
         setActiveSource(null);
-        setIsProcessing(false);
         // Only advance if we're playing and not pausing or skipping
         if (isPlaying && !skipTriggeredRef.current && !isPausingRef.current) {
           processNextSentence();
@@ -218,6 +222,7 @@ export function TTSProvider({ children }: { children: React.ReactNode }) {
     }
 
     skipTriggeredRef.current = true;
+    setIsProcessing(true);
     // Cancel any ongoing request
     if (currentRequestRef.current) {
       currentRequestRef.current.abort();
@@ -239,6 +244,7 @@ export function TTSProvider({ children }: { children: React.ReactNode }) {
     // Reset skip flag after a short delay
     skipTimeoutRef.current = setTimeout(() => {
       skipTriggeredRef.current = false;
+      setIsProcessing(false);
     }, 100);
   }, [sentences, activeSource]);
 
@@ -248,6 +254,7 @@ export function TTSProvider({ children }: { children: React.ReactNode }) {
     }
 
     skipTriggeredRef.current = true;
+    setIsProcessing(true);
     // Cancel any ongoing request
     if (currentRequestRef.current) {
       currentRequestRef.current.abort();
@@ -269,6 +276,7 @@ export function TTSProvider({ children }: { children: React.ReactNode }) {
     // Reset skip flag after a short delay
     skipTimeoutRef.current = setTimeout(() => {
       skipTriggeredRef.current = false;
+      setIsProcessing(false);
     }, 100);
   }, [sentences, activeSource]);
 
@@ -309,10 +317,39 @@ export function TTSProvider({ children }: { children: React.ReactNode }) {
     preloadAdjacentSentences();
   }, [currentIndex, sentences]);
 
+  const isMounted = useRef(false);
+
   useEffect(() => {
-    if (isPlaying && sentences[currentIndex] && !isProcessing) {
-      processAndPlaySentence(sentences[currentIndex]);
+    // Skip the first mount in development
+    if (process.env.NODE_ENV === 'development') {
+      if (!isMounted.current) {
+        isMounted.current = true;
+        return;
+      }
     }
+
+    let isEffectActive = true;
+
+    const playAudio = async () => {
+      if (isPlaying && sentences[currentIndex] && !isProcessing && isEffectActive) {
+        await processAndPlaySentence(sentences[currentIndex]);
+      }
+    };
+
+    playAudio();
+
+    return () => {
+      isEffectActive = false;
+      // Clean up any playing audio when the effect is cleaned up
+      if (activeSource) {
+        activeSource.stop();
+        setActiveSource(null);
+      }
+      if (currentRequestRef.current) {
+        currentRequestRef.current.abort();
+        currentRequestRef.current = null;
+      }
+    };
   }, [isPlaying, currentIndex, sentences, isProcessing]);
 
   const preloadSentence = async (sentence: string) => {
@@ -424,6 +461,7 @@ export function TTSProvider({ children }: { children: React.ReactNode }) {
     setCurrentIndex: setCurrentIndexWithoutPlay,
     stopAndPlayFromIndex,
     sentences,
+    isProcessing,
   };
 
   return (
diff --git a/src/context/ThemeContext.tsx b/src/context/ThemeContext.tsx
new file mode 100644
index 0000000..721f708
--- /dev/null
+++ b/src/context/ThemeContext.tsx
@@ -0,0 +1,75 @@
+'use client';
+
+import { createContext, useContext, useEffect, useState } from 'react';
+
+type Theme = 'light' | 'dark' | 'system';
+
+interface ThemeContextType {
+  theme: Theme;
+  setTheme: (theme: Theme) => void;
+}
+
+const ThemeContext = createContext<ThemeContextType | undefined>(undefined);
+
+const getSystemTheme = () => {
+  if (typeof window === 'undefined') return 'light';
+  return window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light';
+};
+
+const getEffectiveTheme = (theme: Theme): 'light' | 'dark' => {
+  if (theme === 'system') {
+    return getSystemTheme();
+  }
+  return theme;
+};
+
+export function ThemeProvider({ children }: { children: React.ReactNode }) {
+  const [theme, setTheme] = useState<Theme>(() => {
+    if (typeof window === 'undefined') return 'system';
+    return (localStorage.getItem('theme') as Theme) || 'system';
+  });
+
+  const handleThemeChange = (newTheme: Theme) => {
+    const root = window.document.documentElement;
+    const effectiveTheme = getEffectiveTheme(newTheme);
+    
+    root.classList.remove('light', 'dark');
+    root.classList.add(effectiveTheme);
+    root.style.colorScheme = effectiveTheme;
+    
+    localStorage.setItem('theme', newTheme);
+    setTheme(newTheme);
+  };
+
+  // Handle system theme changes
+  useEffect(() => {
+    const mediaQuery = window.matchMedia('(prefers-color-scheme: dark)');
+    
+    const handleChange = () => {
+      if (theme === 'system') {
+        const effectiveTheme = getSystemTheme();
+        const root = window.document.documentElement;
+        root.classList.remove('light', 'dark');
+        root.classList.add(effectiveTheme);
+        root.style.colorScheme = effectiveTheme;
+      }
+    };
+
+    mediaQuery.addEventListener('change', handleChange);
+    return () => mediaQuery.removeEventListener('change', handleChange);
+  }, [theme]);
+
+  return (
+    <ThemeContext.Provider value={{ theme, setTheme: handleThemeChange }}>
+      {children}
+    </ThemeContext.Provider>
+  );
+}
+
+export function useTheme() {
+  const context = useContext(ThemeContext);
+  if (context === undefined) {
+    throw new Error('useTheme must be used within a ThemeProvider');
+  }
+  return context;
+}
diff --git a/src/lib/theme.ts b/src/lib/theme.ts
new file mode 100644
index 0000000..459c435
--- /dev/null
+++ b/src/lib/theme.ts
@@ -0,0 +1,16 @@
+// This will be loaded as a module
+export function initializeTheme() {
+  try {
+    const savedTheme = localStorage.getItem('theme') || 'system';
+    const systemTheme = window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light';
+    const theme = savedTheme === 'system' ? systemTheme : savedTheme;
+    
+    document.documentElement.classList.remove('light', 'dark');
+    document.documentElement.classList.add(theme);
+    document.documentElement.style.colorScheme = theme;
+  } catch (e) {
+    // Fallback to light theme if localStorage is not available
+    document.documentElement.classList.add('light');
+    document.documentElement.style.colorScheme = 'light';
+  }
+}
diff --git a/tailwind.config.ts b/tailwind.config.ts
index 555205d..5db2dd5 100644
--- a/tailwind.config.ts
+++ b/tailwind.config.ts
@@ -6,6 +6,7 @@ export default {
     "./src/components/**/*.{js,ts,jsx,tsx,mdx}",
     "./src/app/**/*.{js,ts,jsx,tsx,mdx}",
   ],
+  darkMode: 'class',
   theme: {
     extend: {
       colors: {
@@ -16,6 +17,31 @@ export default {
         accent: "var(--accent)",
         muted: "var(--muted)",
       },
+      animation: {
+        'spin-slow': 'spin 2s linear infinite',
+        'fade-in': 'fadeIn 200ms ease-in',
+        'fade-out': 'fadeOut 200ms ease-out',
+        'scale-in': 'scaleIn 200ms ease-in',
+        'scale-out': 'scaleOut 200ms ease-out',
+      },
+      keyframes: {
+        fadeIn: {
+          '0%': { opacity: '0' },
+          '100%': { opacity: '1' },
+        },
+        fadeOut: {
+          '0%': { opacity: '1' },
+          '100%': { opacity: '0' },
+        },
+        scaleIn: {
+          '0%': { transform: 'scale(0.95)', opacity: '0' },
+          '100%': { transform: 'scale(1)', opacity: '1' },
+        },
+        scaleOut: {
+          '0%': { transform: 'scale(1)', opacity: '1' },
+          '100%': { transform: 'scale(0.95)', opacity: '0' },
+        },
+      },
     },
   },
   plugins: [],
