UI: Fix layout height

[cdedreuille]

Closes #24261

What I did

To support older browsers we can't use 100dvh to set the height of the layout to be always visible on mobile. Instead, the most reliable way is to set the height using javascript. A common pattern is to set a css variable for --vh that you can then use elsewhere if needed it on your app.

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[ndelangen]

Emotion supports array values for fallbacks:
https://emotion.sh/docs/object-styles#fallbacks

Suggested change

	height: 'var(--vh, 100vh)',
	height: ['100dvh', '100vh],

IIUC, the bug that requires 100dvh only happens on iOS and that supports the CSS feature?

[JReinhold]

This is more about supporting old browser versions, and we haven't yet decided which versions to support in SB 8.0. https://caniuse.com/viewport-unit-variants

The fallback syntax looks interesting, I can't find any info on how this works? Is it a browser feature, or does Emotion do something clever with a list of CSS features per user agent?

based on the docs you linked, I think the syntax is the other way around in your suggestion.

[cdedreuille]

Oh that's interesting. I didn't know Emotion had fallbacks. I'll try it out now.

[ndelangen]

Having the same property twice on a single class is a CSS feature.
CSS is fault-tolerant.

Emotion allows you to use this feature with the array syntax.

True, the exact implementation might have to be reversed from the code suggestion I added.

[cdedreuille]

@JReinhold @ndelangen I've implemented the change and removed the JS code 😊 It does work as intended.