Question

I have tried css

iframe {
        margin: 0px;
        padding: 0px;
        width: 100%;
         height:100%; 

    }

I also tried javascript

function resize()
{
    document.getElementById('dashIframe').style.height = top.main.clientHeight + 'px';

}   

But I can’t get the iframe to be 100% height

Answer 1

Your iframe is taking the height of the parent element. If there is nothing else in the frame making it larger then the height of the body is 0. 100% of 0 is 0.

You have two solutions, either make the body and html of your frame 100% like so.

body, html {
    width: 100%;
    height: 100%;
    margin: 0;
    padding: 0;
}

Or give your iframe absolute positioning, make sure it is not in any other container that has relative or absolute positioning applied. like so..

iframe {
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
}

On a side note framesets are no longer supported in HTML5. So I would probably try and find an alternate solution to your frameset. You can achieve the same visual effects just using divs.