"Example" style used in Bootstrap documentation.

bootstrap-bs-example.css

.bs-example {
  position: relative;
  margin: 15px 0;
  padding: 39px 19px 14px;
  background-color: white;
  border: 1px solid #DDD;
  -webkit-border-radius: 4px;
  -moz-border-radius: 4px;
  border-radius: 4px;
}

.bs-example-title {
  position: absolute;
  top: -1px;
  left: -1px;
  padding: 3px 7px;
  font-size: 12px;
  font-weight: bold;
  background-color: whiteSmoke;
  border: 1px solid #DDD;
  color: #9DA0A4;
  -webkit-border-radius: 4px 0 4px 0;
  -moz-border-radius: 4px 0 4px 0;
  border-radius: 4px 0 4px 0;
}