getCSSProperty = function(element, container, property) {
    var ret = element.style[property];

    if (!ret) {
        if (window.getComputedStyle) {
            ret = window.getComputedStyle(element, '').getPropertyValue(property);
        } else {
            ret = element.currentStyle[property];
        }
    }

    if (!ret || ret == 'auto' || ret == 'intrinsic') {
        ret = container.style[property];
    }
    return ret;
}
Returns the CSS property of element.
  1) If the CSS property is on the style object of the element, use it, OR
  2) Compute the CSS property

If the property can't get computed, is 'auto' or 'intrinsic', the former
calculated property is uesd (this can happen in cases where the textarea
is hidden and has no dimension styles).