div.md-content img { border: 4px solid #ddd; padding: 12px; }
.callout {
  padding: 20px;
  margin: 20px 0;
  border: 1px solid #eee;
  border-left-width: 5px;
  border-radius: 3px;
  h4 {
    margin-top: 0;
    margin-bottom: 1px;
  }
  p:last-child {
    margin-bottom: 0;
  }
  code {
    border-radius: 3px;
  }
}
.callout-info {
  border-left-color: #428bca;
  h4 {
       color: #428bca;
  }
}
.callout-primary {
  border-left-color: #5bc0de;
  h4 {
       color: #5bc0de;
  }
}
.callout-danger {
 border-left-color: #d9534f;
  h4 {
       color: #d9534f;
  }
}