Line of three segments colors html5 css3.

<style type="text/css">

div {
 position: relative;
 width: 430px;
 height: 40px;
 font-size: 27px;
 font-weight: bold;
 font-family: verdana;
}
div:after {
 content: '';
 left: 0;
 bottom: -3px;
 position: absolute;
 width: 100%;
 height: 4px;
 background: linear-gradient(to right, red, green, blue);
}

</style>

<div>This is CSS jQuery Blog.....</div>


Output :)