body {
  font-family: Arial, sans-serif;
  font-size: 1.3em;
}

#mainDiv {
  width: 600px;
  border: 1px solid gray;
  border-radius: 20px;
  padding: 20px;
  margin: 0 auto;
}

.attention {
  font-weight: bold;
  color: #F00;
}

#newContentsDiv {
  border: 1px solid gray;
  border-radius: 10px;
  margin: 20px;
  padding: 10px;
}