Insert image after each list item

For IE8 support, the "content" property cannot be empty.

To get around this I've done the following :

.ul li:after {
    content:"icon";
    text-indent:-999em;
    display:block;
    width:32px;
    height:32px;
    background:url(../img/icons/spritesheet.png) 0 -620px no-repeat;
    margin:5% 0 0 45%;
}

Note : This works with image sprites too

Try this:

ul li a:after {
    display: block;
    content: "";
    width: 3px;
    height: 5px;
    background: transparent url('../images/small_triangle.png') no-repeat;
}

You need the content: ""; declaration to give your generated element content, even if that content is "nothing".

Also, I fixed the syntax/ordering of your background declaration.

I think your problem is that the :after psuedo-element requires the content: property set inside it. You need to tell it to insert something. You could even just have it insert the image directly:

ul li:after {
    content: url('../images/small_triangle.png');
}

The easier way to do it is just:

ul li:after {
    content: url('../images/small_triangle.png');
}