diff --git a/Web/templates/base.html b/Web/templates/base.html
index 007405e..9f8c761 100755
--- a/Web/templates/base.html
+++ b/Web/templates/base.html
@@ -1136,7 +1136,7 @@
                         </li>
                         {% endif %}
                         <li class="nav-item" data-nav-fixed="true">
-                            <button id="themeToggleBtn" class="btn btn-link nav-link px-3" aria-label="Dark Mode umschalten" title="Theme umschalten">
+                            <button type="button" class="btn btn-link nav-link px-3" data-theme-toggle aria-label="Dark Mode umschalten" aria-pressed="false" title="Theme umschalten">
                                 <span class="theme-icon-light" style="display: none;">☀️</span>
                                 <span class="theme-icon-dark" style="display: none;">🌙</span>
                             </button>
@@ -1229,7 +1229,7 @@
                         {% endif %}
                         {% endif %}
                         <li class="nav-item" data-nav-fixed="true">
-                            <button id="themeToggleBtn" class="btn btn-link nav-link px-3" aria-label="Dark Mode umschalten" title="Theme umschalten">
+                            <button type="button" class="btn btn-link nav-link px-3" data-theme-toggle aria-label="Dark Mode umschalten" aria-pressed="false" title="Theme umschalten">
                                 <span class="theme-icon-light" style="display: none;">☀️</span>
                                 <span class="theme-icon-dark" style="display: none;">🌙</span>
                             </button>
@@ -1358,7 +1358,7 @@
                         </li>
                         {% endif %}
                         <li class="nav-item" data-nav-fixed="true">
-                            <button id="themeToggleBtn" class="btn btn-link nav-link px-3" aria-label="Dark Mode umschalten" title="Theme umschalten">
+                            <button type="button" class="btn btn-link nav-link px-3" data-theme-toggle aria-label="Dark Mode umschalten" aria-pressed="false" title="Theme umschalten">
                                 <span class="theme-icon-light" style="display: none;">☀️</span>
                                 <span class="theme-icon-dark" style="display: none;">🌙</span>
                             </button>
@@ -2345,33 +2345,56 @@
 
     <!-- Theme Toggle Script -->
     <script>
-        document.addEventListener('DOMContentLoaded', () => {
-            const toggleBtns = document.querySelectorAll('#themeToggleBtn');
-            if (toggleBtns.length === 0) return;
-            
-            function updateIcons(theme) {
-                const isDark = theme === 'dark';
-                document.querySelectorAll('.theme-icon-light').forEach(icon => icon.style.display = isDark ? 'inline' : 'none');
-                document.querySelectorAll('.theme-icon-dark').forEach(icon => icon.style.display = isDark ? 'none' : 'inline');
+        (function () {
+            const root = document.documentElement;
+            const metaThemeColor = document.getElementById('meta-theme-color');
+            const themeToggleSelector = '[data-theme-toggle]';
+
+            function getTheme() {
+                return root.getAttribute('data-theme') === 'dark' ? 'dark' : 'light';
             }
 
-            // Get current setup from initial script in head
-            let currentTheme = document.documentElement.getAttribute('data-theme') || 'light';
-            updateIcons(currentTheme);
+            function updateThemeUi(theme) {
+                const isDark = theme === 'dark';
+                document.querySelectorAll('.theme-icon-light').forEach(icon => {
+                    icon.style.display = isDark ? 'inline' : 'none';
+                });
+                document.querySelectorAll('.theme-icon-dark').forEach(icon => {
+                    icon.style.display = isDark ? 'none' : 'inline';
+                });
+                document.querySelectorAll(themeToggleSelector).forEach(button => {
+                    button.setAttribute('aria-pressed', String(isDark));
+                    button.setAttribute('aria-label', isDark ? 'Light Mode einschalten' : 'Dark Mode einschalten');
+                    button.setAttribute('title', isDark ? 'Light Mode einschalten' : 'Dark Mode einschalten');
+                });
+                if (metaThemeColor) {
+                    metaThemeColor.setAttribute('content', isDark ? '#1a252f' : '#2c3e50');
+                }
+            }
 
-            toggleBtns.forEach(btn => {
-                btn.addEventListener('click', (e) => {
-                    e.preventDefault();
-                    currentTheme = currentTheme === 'light' ? 'dark' : 'light';
-                    
-                    document.documentElement.setAttribute('data-theme', currentTheme);
-                    localStorage.setItem('inventarsystem-theme', currentTheme);
-                    document.getElementById('meta-theme-color').setAttribute('content', currentTheme === 'dark' ? '#1a252f' : '#2c3e50');
-                    
-                    updateIcons(currentTheme);
+            function applyTheme(theme, persist) {
+                const normalizedTheme = theme === 'dark' ? 'dark' : 'light';
+                root.setAttribute('data-theme', normalizedTheme);
+                if (persist) {
+                    try {
+                        localStorage.setItem('inventarsystem-theme', normalizedTheme);
+                    } catch (error) {
+                        console.warn('Theme konnte nicht gespeichert werden:', error);
+                    }
+                }
+                updateThemeUi(normalizedTheme);
+            }
+
+            document.addEventListener('DOMContentLoaded', function () {
+                updateThemeUi(getTheme());
+                document.addEventListener('click', function (event) {
+                    const button = event.target.closest(themeToggleSelector);
+                    if (!button) return;
+                    event.preventDefault();
+                    applyTheme(getTheme() === 'dark' ? 'light' : 'dark', true);
                 });
             });
-        });
+        })();
     </script>
     <script>
         (function () {