fix button on error page

src/main/resources/templates/error.html

@@ -26,9 +26,9 @@
                 <p th:text="${message}"></p>
             </div>
         </div>
-
-        <button style="color: #52a1eb">
-            <a  style="color: white" class="btn btn-primary btn-lg" href="#" onclick="window.history.back(-1);return false;" role="button">Zurück</a>
+        <button class="btn btn-primary"
+                style="background: #52a1eb; border-style: none;">
+            <a  style="color: white" href="#" onclick="window.history.back(-1);return false;" role="button">Zurück</a>
         </button>
     </div>
 </div>