Question

Can’t I have both box shadow inner and outer on the same div?
I’ve tried but it doesn’t work

http://jsfiddle.net/CWuw8/

div{
    top: 100px;
    position: absolute;
    left: 100px;
    height: 100px;
    width: 100px;
    box-shadow: 10px 10px 10px;
    box-shadow: 0 0 10px inset;
    border-radius: 5px;
    background: white;
}

body{background: #d14343}

<div></div>

Answer 1

You need to use comma to separate both shadows: http://jsfiddle.net/gryzzly/CWuw8/3/

And you must also specify the color for your shadow in order for it to be seen.

div{
    top: 100px;
    position: absolute;
    left: 100px;
    height: 100px;
    width: 100px;
    box-shadow: 
        10px 10px 10px #000, 
        inset 0 0 10px #000;
    border-radius: 5px;
    background: white;
}

body{background: #d14343}

<div></div>