WebGL different behavior on Mac Monitor

Hi,

we have this method:
setMargins: function (name, left, top, right, bottom) {
var container = $('#unity-container');
var width = container.width();
var height = container.height();

    var lp = left / width * 100;
    var tp = top / height * 100;
    var wp = (width - left - right) / width * 100;
    var hp = (height - top - bottom) / height * 100;

    this.iframe(name)
        .css('left', lp + '%')
        .css('top', tp + '%')
        .css('width', wp + '%')
        .css('height', hp + '%');
}

Not sure if it's our own implementation or this is something you provided.
Anyway - I am trying to open the webview on part of the screen. This is basically the first time we do this, most of the time we open it full screen.
I have an issue where everything works correctly in the connected monitor, but on the Mac's built in screen, it seems that the height is set to 0% (and top is set to 80% for example). This also reproduces for another developer, so it's not just my machine.

Can you try and help me? Do you have an idea why would it behave differently on different monitors (I'm assuming resolution)?

Start with the shown setMargins method and inspect how #unity-container dimensions and iframe sizing are obtained in the WebGL path. Reproduce the zero-height result on the built-in and external Mac displays, then document or fix the monitor-dependent sizing behavior and verify the iframe receives nonzero dimensions.