"Example" style used in Bootstrap documentation.

gistfile1.css

.bs-docs-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-docs-example::after
{
    content: "Example";
    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;
}