Send a custom height to pym

pym_custom_height.js

// update height, sending an extra 20 pixels to be safe
const mainElementHeight = (document.getElementsByTagName('body')[0].offsetHeight + 20).toString();
pymChild.sendMessage('height', mainElementHeight);

//// may need to add this:
// instantiate pym object
window.pymChild = new Child();

// or, for cnn rig, inside your draw function:
pymChild.sendMessage('height', initialHeight);

// a second later send security height in hopes of resetting to actual height
setTimeout(() => { pymChild.sendHeight(); }, 1000);