Template:Callout/styles.css

.callout {
  border-left: 3px solid #999;
  padding: 0.75em 1em;
  margin: 1em 0;
}

.callout-label {
  font-weight: bold;
  margin-right: 0.25em;
}

.callout-tip {
  border-left-color: #4a90e2;
}

.callout-warning {
  border-left-color: #d9534f;
}

.callout-protip {
  border-left-color: #5cb85c;
}

.callout-note {
  border-left-color: #999;
}