how to create Hollow triangle in css [duplicate]

Answer 1

Forking off rajesh kakawat - you can get the same effect with one div: http://jsfiddle.net/aDcTb/

<div id="triangle"></div>

#triangle {
        left:10px;
        width: 0; 
        height: 0; 
        border-left: 100px solid transparent;
        border-right: 100px solid transparent;
        border-bottom: 100px solid black;
    }
    #triangle:after {
        left:10px;
        width: 0; 
        height: 0; 
        border-left: 50px solid transparent;
        border-right: 50px solid transparent;
        border-bottom: 50px solid #FFF;
        left: 57px;
        position: absolute;
        top: 38px;
        content: '';
    }

Answer 2

I don't have solution but i have workaround with two triangle, FIDDLE

HTML CODE

<div id="tringle"></div>
<div id="tringle2"></div>

CSS CODE

    #tringle {
        left:10px;
        width: 0; 
        height: 0; 
        border-left: 100px solid transparent;
        border-right: 100px solid transparent;
        border-bottom: 100px solid black;
    }
    #tringle2 {

        left:10px;
        width: 0; 
        height: 0; 
        border-left: 50px solid transparent;
        border-right: 50px solid transparent;
        border-bottom: 50px solid #FFF;
        left: 57px;
        position: absolute;
        top: 38px;

    }

Answer 3

Not exactly cross-browser but works. Hope I've understood your request.

http://jsfiddle.net/wmDNr/3/

 .triangle { 
     position: relative;
     width: 20px;
     margin-top: 100px;
 }
 .triangle>div { 
     width: 20px;
     height: 2px;
     background: red;
     margin-top: 100px;
 }

 .triangle>div:before {
     content: " ";
     display: block;
     width: 20px;
     height: 2px;
     background: red;
     -webkit-transform: rotate(56deg);
     -moz-transform: rotate(56deg);
     -ms-transform: rotate(56deg);
     transform: rotate(56deg);
     position: absolute;
     top: -8px;
     right: -5px;
 }
 .triangle>div:after {
     content: " ";
     display: block;
     width: 20px;
     height: 2px;
     background: red;
     -webkit-transform: rotate(-56deg);
     -moz-transform: rotate(-56deg);
     -ms-transform: rotate(-56deg);
     transform: rotate(-56deg);
     position: absolute;
     top: -8px;
     left: -5px;
 }