fix larghezza input form

Author: trailhead-loris

index.html

@@ -10,7 +10,7 @@
     .login-box h2 { margin: 0 0 16px; }
     .field { margin-bottom: 12px; }
     .field label { display: block; font-size: 13px; margin-bottom: 6px; color: #444; }
-    .field input { width: 100%; padding: 10px 12px; border: 1px solid #d0d7de; border-radius: 6px; font-size: 14px; }
+    .field input { width: 100%; padding: 10px 12px; border: 1px solid #d0d7de; border-radius: 6px; font-size: 14px; box-sizing: border-box; }
     button { width: 100%; padding: 10px 14px; background: #0969da; color: #fff; border: none; border-radius: 6px; font-weight: bold; cursor: pointer; }
     button:hover { background: #0758b7; }
     .note { font-size: 12px; color: #666; margin-top: 10px; }