diff --git a/package.json b/package.json
index a70f416..eced4e9 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "jmespath-playground",
-  "version": "1.0.0",
+  "version": "1.0.1",
   "description": "A React-based web application for testing JMESPath expressions against JSON data",
   "main": "index.js",
   "scripts": {
diff --git a/src/App.css b/src/App.css
index 25b7649..211d802 100644
--- a/src/App.css
+++ b/src/App.css
@@ -107,6 +107,295 @@ footer a:hover {
   }
 }
 
+/* Manual theme overrides */
+.theme-light {
+  /* Force light theme regardless of system preference */
+  background-color: #ffffff !important;
+  color: #212529 !important;
+}
+
+.theme-light .header-section {
+  background-color: transparent !important;
+  border-bottom: none !important;
+}
+
+.theme-light .card {
+  background-color: #ffffff !important;
+  box-shadow: 0 2px 8px rgba(0,0,0,0.1) !important;
+  color: #212529 !important;
+}
+
+.theme-light .card-header {
+  background-color: #f8f9fa !important;
+  border-bottom: 2px solid #dee2e6 !important;
+  color: #212529 !important;
+}
+
+.theme-light .jmespath-input {
+  background-color: #ffffff !important;
+  border: 1px solid #ced4da !important;
+  color: #495057 !important;
+}
+
+.theme-light .json-input, 
+.theme-light .result-output {
+  background-color: #f8f9fa !important;
+  border: 1px solid #dee2e6 !important;
+  color: #495057 !important;
+}
+
+.theme-light .text-muted {
+  color: #6c757d !important;
+}
+
+.theme-light .jmespath-input:focus {
+  background-color: #ffffff !important;
+  border-color: #007bff !important;
+  color: #495057 !important;
+  box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, 0.25) !important;
+}
+
+.theme-light .jmespath-input::placeholder {
+  color: #6c757d !important;
+}
+
+.theme-light .json-input::placeholder, 
+.theme-light .result-output::placeholder {
+  color: #6c757d !important;
+}
+
+.theme-light .json-input:focus, 
+.theme-light .result-output:focus {
+  background-color: #ffffff !important;
+  border-color: #007bff !important;
+  color: #495057 !important;
+  box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, 0.25) !important;
+}
+
+.theme-light .alert-danger {
+  background-color: #f8d7da !important;
+  border-color: #f5c6cb !important;
+  color: #721c24 !important;
+}
+
+.theme-light .btn-primary {
+  background-color: #007bff !important;
+  border-color: #007bff !important;
+  color: #ffffff !important;
+}
+
+.theme-light .btn-outline-secondary {
+  color: #6c757d !important;
+  border-color: #6c757d !important;
+}
+
+.theme-light .btn-outline-secondary:hover {
+  background-color: #6c757d !important;
+  border-color: #6c757d !important;
+  color: #ffffff !important;
+}
+
+.theme-light .btn-outline-success {
+  color: #28a745 !important;
+  border-color: #28a745 !important;
+}
+
+.theme-light .btn-outline-success:hover {
+  background-color: #28a745 !important;
+  border-color: #28a745 !important;
+  color: #ffffff !important;
+}
+
+.theme-light .btn-outline-info {
+  color: #17a2b8 !important;
+  border-color: #17a2b8 !important;
+}
+
+.theme-light .btn-outline-info:hover {
+  background-color: #17a2b8 !important;
+  border-color: #17a2b8 !important;
+  color: #ffffff !important;
+}
+
+.theme-light .btn-outline-primary {
+  color: #007bff !important;
+  border-color: #007bff !important;
+}
+
+.theme-light .btn-outline-primary:hover {
+  background-color: #007bff !important;
+  border-color: #007bff !important;
+  color: #ffffff !important;
+}
+
+.theme-light .btn-outline-danger {
+  color: #dc3545 !important;
+  border-color: #dc3545 !important;
+}
+
+.theme-light .btn-outline-danger:hover {
+  background-color: #dc3545 !important;
+  border-color: #dc3545 !important;
+  color: #ffffff !important;
+}
+
+.theme-light footer {
+  background-color: #f8f9fa !important;
+  border-top: 1px solid #dee2e6 !important;
+  color: #212529 !important;
+}
+
+.theme-light footer a {
+  color: #6c757d !important;
+}
+
+.theme-light footer a:hover {
+  color: #495057 !important;
+}
+
+/* Force dark theme regardless of system preference */
+.theme-dark {
+  background-color: #1a1a1a !important;
+  color: #e9ecef !important;
+}
+
+.theme-dark .header-section {
+  background-color: #2d2d2d !important;
+  border-bottom: 1px solid #404040 !important;
+}
+
+.theme-dark .card {
+  background-color: #2d2d2d !important;
+  box-shadow: 0 2px 8px rgba(0,0,0,0.3) !important;
+  color: #e9ecef !important;
+}
+
+.theme-dark .card-header {
+  background-color: #3a3a3a !important;
+  border-bottom: 2px solid #505050 !important;
+  color: #f8f9fa !important;
+}
+
+.theme-dark .jmespath-input {
+  background-color: #3a3a3a !important;
+  border: 1px solid #505050 !important;
+  color: #f8f9fa !important;
+}
+
+.theme-dark .jmespath-input::placeholder {
+  color: #adb5bd !important;
+}
+
+.theme-dark .jmespath-input:focus {
+  background-color: #404040 !important;
+  border-color: #007bff !important;
+  color: #ffffff !important;
+}
+
+.theme-dark .json-input, 
+.theme-dark .result-output {
+  background-color: #2a2a2a !important;
+  border: 1px solid #505050 !important;
+  color: #e9ecef !important;
+}
+
+.theme-dark .json-input::placeholder, 
+.theme-dark .result-output::placeholder {
+  color: #6c757d !important;
+}
+
+.theme-dark .json-input:focus, 
+.theme-dark .result-output:focus {
+  background-color: #323232 !important;
+  border-color: #007bff !important;
+  color: #ffffff !important;
+}
+
+.theme-dark .alert-danger {
+  background-color: #3d1a1a !important;
+  border-color: #dc3545 !important;
+  color: #f8d7da !important;
+}
+
+.theme-dark .text-muted {
+  color: #adb5bd !important;
+}
+
+.theme-dark footer {
+  background-color: #2d2d2d !important;
+  border-top: 1px solid #404040 !important;
+  color: #e9ecef !important;
+}
+
+.theme-dark footer a {
+  color: #adb5bd !important;
+}
+
+.theme-dark footer a:hover {
+  color: #e9ecef !important;
+}
+
+.theme-dark .btn-primary {
+  background-color: #007bff !important;
+  border-color: #007bff !important;
+  color: #ffffff !important;
+}
+
+.theme-dark .btn-outline-secondary {
+  color: #6c757d !important;
+  border-color: #6c757d !important;
+}
+
+.theme-dark .btn-outline-secondary:hover {
+  background-color: #6c757d !important;
+  border-color: #6c757d !important;
+  color: #ffffff !important;
+}
+
+.theme-dark .btn-outline-success {
+  color: #28a745 !important;
+  border-color: #28a745 !important;
+}
+
+.theme-dark .btn-outline-success:hover {
+  background-color: #28a745 !important;
+  border-color: #28a745 !important;
+  color: #ffffff !important;
+}
+
+.theme-dark .btn-outline-info {
+  color: #17a2b8 !important;
+  border-color: #17a2b8 !important;
+}
+
+.theme-dark .btn-outline-info:hover {
+  background-color: #17a2b8 !important;
+  border-color: #17a2b8 !important;
+  color: #ffffff !important;
+}
+
+.theme-dark .btn-outline-primary {
+  color: #007bff !important;
+  border-color: #007bff !important;
+}
+
+.theme-dark .btn-outline-primary:hover {
+  background-color: #007bff !important;
+  border-color: #007bff !important;
+  color: #ffffff !important;
+}
+
+.theme-dark .btn-outline-danger {
+  color: #dc3545 !important;
+  border-color: #dc3545 !important;
+}
+
+.theme-dark .btn-outline-danger:hover {
+  background-color: #dc3545 !important;
+  border-color: #dc3545 !important;
+  color: #ffffff !important;
+}
+
 /* Dark mode support */
 @media (prefers-color-scheme: dark) {
   body {
diff --git a/src/App.js b/src/App.js
index c59ca38..1cd6aef 100644
--- a/src/App.js
+++ b/src/App.js
@@ -5,6 +5,10 @@ import './App.css';
 // JMESPath Testing Tool - Main Application Component
 function App() {
   const [jmespathExpression, setJmespathExpression] = useState('people[0].name');
+  const [theme, setTheme] = useState(() => {
+    // Load theme from localStorage or default to 'auto'
+    return localStorage.getItem('theme') || 'auto';
+  });
   const [jsonData, setJsonData] = useState(`{
   "people": [
     {
@@ -24,6 +28,29 @@ function App() {
   const [error, setError] = useState('');
   const [jsonError, setJsonError] = useState('');
 
+  // Theme management
+  useEffect(() => {
+    // Apply theme to document
+    const applyTheme = (selectedTheme) => {
+      const root = document.documentElement;
+      root.className = ''; // Clear existing theme classes
+      
+      if (selectedTheme === 'light') {
+        root.classList.add('theme-light');
+      } else if (selectedTheme === 'dark') {
+        root.classList.add('theme-dark');
+      }
+      // 'auto' uses CSS media queries (no class needed)
+    };
+
+    applyTheme(theme);
+    localStorage.setItem('theme', theme);
+  }, [theme]);
+
+  const handleThemeChange = (newTheme) => {
+    setTheme(newTheme);
+  };
+
   const evaluateExpression = () => {
     try {
       // Clear previous errors
@@ -185,8 +212,37 @@ function App() {
       <div className="header-section py-2">
         <div className="container">
           <div className="row">
-            <div className="col-12 text-center">
+            <div className="col-12 text-center position-relative">
               <h2 className="mb-1">JMESPath Testing Tool</h2>
+              {/* Theme switcher */}
+              <div className="position-absolute top-0 end-0">
+                <div className="btn-group btn-group-sm" role="group" aria-label="Theme switcher">
+                  <button 
+                    type="button" 
+                    className={`btn ${theme === 'auto' ? 'btn-primary' : 'btn-outline-secondary'}`}
+                    onClick={() => handleThemeChange('auto')}
+                    title="Auto (follow system)"
+                  >
+                    🌓 Auto
+                  </button>
+                  <button 
+                    type="button" 
+                    className={`btn ${theme === 'light' ? 'btn-primary' : 'btn-outline-secondary'}`}
+                    onClick={() => handleThemeChange('light')}
+                    title="Light theme"
+                  >
+                    ☀️ Light
+                  </button>
+                  <button 
+                    type="button" 
+                    className={`btn ${theme === 'dark' ? 'btn-primary' : 'btn-outline-secondary'}`}
+                    onClick={() => handleThemeChange('dark')}
+                    title="Dark theme"
+                  >
+                    🌙 Dark
+                  </button>
+                </div>
+              </div>
             </div>
           </div>
         </div>
diff --git a/src/index.css b/src/index.css
index 7dee381..c25b1c2 100644
--- a/src/index.css
+++ b/src/index.css
@@ -92,4 +92,26 @@ code {
 .result-output {
   background-color: #e7f3ff;
   border-color: #b3d7ff;
+}
+
+/* Dark mode support for error states */
+@media (prefers-color-scheme: dark) {
+  .error {
+    background-color: #4a1e1e !important;
+    border-color: #6d2c2c !important;
+    color: #f8d7da !important;
+  }
+}
+
+/* Manual theme overrides for error states */
+.theme-dark .error {
+  background-color: #4a1e1e !important;
+  border-color: #6d2c2c !important;
+  color: #f8d7da !important;
+}
+
+.theme-light .error {
+  background-color: #f8d7da !important;
+  border-color: #f5c6cb !important;
+  color: #721c24 !important;
 }
\ No newline at end of file