Updates a css variable with the scale of the window height related to a default height.

set-css-var.js

const DefaultHeight = 768;

init() {
	this.updateRootCSSScale();

	window.addEventListener('resize', e => {
		this.updateRootCSSScale();
	});
}

private updateRootCSSScale() {
 	// Limit to a max value of 1.
	const perc = Math.min(1, window.innerHeight / DefaultHeight);

	// Mapping to a new scale
	const percMod = MathUtils.map(perc, 0, 1, 0.4, 1);

	console.log(`perc`, perc, percMod);
	document.documentElement.style.setProperty('--vertical-scale', String(percMod));
}