While on expandable popups, using the same technique as above for expanding the width of popups has odd results. So for this, I add the same css for the height, but instead of setting the popup view width to auto, I explicitly set the props.defaultSize.width value with a binding which dynamically changes the width of the popup in the client.
CSS:
.ia_popup[id^="popup-"]{
width: auto !important;
}
Edit: forgot to attach the demo:
There's a bit of a glitch where if the popup was set to open using auto positioning in the centre of the page and you haven't moved it, expanding it will continue to honour this. If you move it however, then the positioning becomes absolute and the popup will keep its top/left position when it's resized.