Pure CSS 3D Ribbon by James Koster (http://jameskoster.co.uk/snippets/pure-css-3d-ribbon/)

3dribbon

.ribbon {
 font-size: 16px !important;
 /* This ribbon is based on a 16px font side and a 24px vertical rhythm. I've used em's to position each element for scalability. If you want to use a different font size you may have to play with the position of the ribbon elements */

 width: 50%;
    
 position: relative;
 background: #ba89b6;
 color: #fff;
 text-align: center;
 padding: 1em 2em; /* Adjust to suit */
 margin: 2em auto 3em; /* Based on 24px vertical rhythm. 48px bottom margin - normally 24 but the ribbon 'graphics' take up 24px themselves so we double it. */
}
.ribbon:before, .ribbon:after {
 content: "";
 position: absolute;
 display: block;
 bottom: -1em;
 border: 1.5em solid #986794;
 z-index: -1;
}
.ribbon:before {
 left: -2em;
 border-right-width: 1.5em;
 border-left-color: transparent;
}
.ribbon:after {
 right: -2em;
 border-left-width: 1.5em;
 border-right-color: transparent;
}
.ribbon .ribbon-content:before, .ribbon .ribbon-content:after {
 content: "";
 position: absolute;
 display: block;
 border-style: solid;
 border-color: #804f7c transparent transparent transparent;
 bottom: -1em;
}
.ribbon .ribbon-content:before {
 left: 0;
 border-width: 1em 0 0 1em;
}
.ribbon .ribbon-content:after {
 right: 0;
 border-width: 1em 1em 0 0;
}