body {
     font-family: Arial, sans-serif;
     background: #f4f4f4;
     padding: 20px;
     margin: 0;
 }

 .container {
     max-width: 900px;
     margin: auto;
     background: #fff;
     padding: 20px;
     border-radius: 8px;
     box-shadow: 0 2px 6px rgba(0, 0, 0, 0.1);
 }

 h1 {
     text-align: center;
 }

 #editor {
     height: 300px;
     width: 100%;
     border: 1px solid #ccc;
     margin-bottom: 15px;
 }

 .buttons {
     text-align: center;
     margin-bottom: 20px;
 }

 button {
     padding: 10px 20px;
     font-size: 1rem;
     margin: 5px;
     border: none;
     border-radius: 4px;
     cursor: pointer;
     color: white;
 }

 .validate-btn {
     background-color: #007BFF;
 }

 .validate-btn:hover {
     background-color: #0056b3;
 }

 .back-btn {
     background-color: #6c757d;
 }

 .back-btn:hover {
     background-color: #5a6268;
 }

 .result {
     margin-top: 20px;
     padding: 10px;
     background: #eef;
     border-radius: 4px;
     font-family: monospace;
 }

 .error {
     color: red;
     font-weight: bold;
 }