Allows use of variables and block inclusions as well as arbitrarily nested blocks

Example syntax:

/* sample.cssx */

$red = #f00;
$block = {
    div {
        padding: 10px;
    }
    color: $red;
    border-width: 1px;
    margin: 20px 10px 15px 0;
}

.warning {
    color: $red;
}

.content {
    .warning {
        width: 200px;
    }

    cite { @rule($block); }

    p {
        span.tooltip {
            color: blue;
        }
        font-size: 1.1em;
    }

    .header {
        @rule($block);
        font-size: 0.8em;
    }

    font-family: Verdana, Arial, sans-serif;
}