I\'m trying to replicate the following shape with no success:

I\'m gue
See a demo - basically it uses css triangles and a pseudo element to give a place for the triangle.
.shape {
position: relative;
width: 78px;
height:30px;
background:#3a93d0;
}
.shape:after {
content: '';
display: block;
position: absolute;
top: 100%;
width: 0;
height: 0;
border-style: solid;
border-width: 25px 39px 0 39px;
border-color: #3a93d0 transparent transparent transparent;
}