Possible Duplicate:
How to create a triangle in CSS3 using border-radius
Are they possible to make with CSS?
Normal arrow:
.some_element:after{
content: '';
height: 0;
width: 0;
position: absolute;
top: 0;
left: 0;
border: 100px solid transparent;
border-top-color: #000;
}
( http://jsfiddle.net/W3xwE/ )
Rounded arrow (I want only the bottom side rounded):

🙁
Yes, it is possible! You
rotatethe box, give it aborder-radiusand use a45deglinear-gradientas abackground.DEMO
HTML:
CSS:
If you want the angle of the arrow to be different, then you can also
skewit.Take into account the fact that CSS gradients are not supported by IE9 (I am not saying “or older” this time because you mention CSS3 among your tags). The solution in that case would be to use a solid background and to somehow make sure the upper part won’t show, either by covering it with a preceding element, or by clipping it (see the answer Tim Medora provided).
Also, at this point there is still no support for the unprefixed syntax (although this will soon change 😀 ), so you will need to either manually add the prefixes
-webkit-,-moz-, and-o-. (I did not add them in the demo because Dabblet uses -prefix-free which takes care of doing this.)