set a max-height to avoid ugly layout with a big height value

mentoring/public/css/questionnaire.css

@@ -42,6 +42,7 @@
     font-family: arial;
     font-size: 14px;
     height: 100%;
+    max-height: 100%;
     opacity: 0.9;
     padding: 10px;
     width: 300px;