Add flight number input cleaning

Author: mschmid09

templates/index.html

@@ -92,15 +92,15 @@ <h1>Create Flight Calendar Event</h1>
 
     <!-- Error message block -->
     {% if error %}
-    <div class="error-message">
+        <div class="error-message">
         {{ error }}
-    </div>
+        </div>
     {% endif %}
 
     <p>Enter your flight number and date to create an iCal event.</p>
     <form action="/create_event" method="post">
         <label for="flight_number">Flight Number:</label>
-        <input type="text" id="flight_number" name="flight_number" required><br><br>
+        <input type="text" id="flight_number" name="flight_number" required oninput="this.value = this.value.toUpperCase().replace(/[^A-Z0-9]/g, '')"><br><br>
 
         <label for="flight_date">Flight Date:</label>
         <input type="date" id="flight_date" name="flight_date" required><br><br>