http://nicolasgallagher.com/progressive-enhancement-pure-css-speech-bubbles/

/* Bubble with an isoceles triangle
------------------------------------------ */

.triangle-isosceles {
   position:relative;
   padding:15px;
   margin:1em 0 3em;
   color:#000;
   background:#f3961c;

   /* css3 */
   -moz-border-radius:10px;
   -webkit-border-radius:10px;
   border-radius:10px;
   background:-moz-linear-gradient(top, #f9d835, #f3961c);
   background:linear-gradient(top, #f9d835, #f3961c);
}

/* creates triangle */
.triangle-isosceles:after {
   content:"\00a0";
   display:block; /* reduce the damage in FF3.0 */
   position:absolute;
   z-index:-1;
   bottom:-30px;
   left:50px;
   width:0;
   height:0;
   border-width:15px 15px;
   border-style:solid;
   border-color:#f3961c transparent transparent;
}

http://nicolasgallagher.com/progressive-enhancement-pure-css-speech-bubbles/

pure CSS speech bubbles

css, 3

CSS