jsFiddle

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• Result
• CSS

div.triangle{
    height:0px;
    width: 0px;
    border-style: solid;
    border-color: transparent transparent transparent black;
    border-width: 50px;
}

div#two {
    margin-top: 20px;
    border-color: #f0f0f0 #ccc #585858 #aaa;
}