Known issues

[foolip]

What are some known issues with viewport units / viewport measurement?

web-platform-tests/interop#41 lists some.

w3c/csswg-drafts#6453 also came across my radar, but I'm not sure if it's an interop issue, I don't know current browser behavior.

[bramus]

One thing that's on my radar is the inconsistency between Safari and Chrome when it comes to viewport units and the keyboard.

As I understand it from running some tests using https://urlbarsize.netlify.app/urlbarsize-allowresize.html (forked from https://bokand.github.io/demo/urlbarsize.html to also include a textfield you can focus):

• Safari on iOS calculates 100vh against the layout viewport. When the keyboard gets shown/hidden, the calculated value for 100vh does not change. The keyboard does not really overlay the contents, but Safari does this thing where it shifts the layout viewport up
• In Chrome on Android, 100vh is calculated against the visual viewport. When the keyboard gets shown/hidden, the calculated value for 100vh changes along with that.

Could be that (part of) this gets solved when the Virtual Keyboard API lands (allowing devs to set overlaysContent to true), but would be nice to see all browsers use the same default behavior there.

[foolip]

The thread in https://twitter.com/madebyfabian/status/1460376294332456968 is about virtual keyboard interaction, with @jensimmons and Maciej chimed in.

[bfgeek]

There is also w3c/csswg-drafts#7194

[gsnedders]

• Relationship between initial containing block and layout viewport and visual viewport is unspecified,
• height: -webkit-fill-available is widely used, but is still prefixed everywhere (v. stretch, got deferred to L4, and appears practically untested in WPT,
• CSSOM attributes like innerHeight still refer to the old CSS 2 definition of viewport, so it's unspecified what they do with dynamic viewports,
• Lack of WPT infrastructure to test dynamic viewport behaviour.

[bramus]

Mentioning w3c/csswg-drafts#7194 as related

[foolip]

https://github.com/bokand/bokand.github.io/blob/master/web_viewports_explainer.md#initial-containing-block-icb might be relevant here.

[bramus]

Closing this issue as we will be discussing items listed here in separate issues.