Sizing Explainer: Add findings for window.{inner|outer}{Height|Width}

explainers/sizing.md

@@ -4,6 +4,8 @@ There are various ways to try and read the size of the viewport/window.
 
 ## `window.innerWidth` and `window.innerHeight`
 
+### Definition
+
 `window.innerWidth` and `window.innerHeight` are defined in the [CSSOM View Module](https://drafts.csswg.org/cssom-view/#dom-window-innerwidth):
 
 > The `innerWidth` attribute must return the viewport[^fn1] width including the size of a rendered scroll bar (if any), or zero if there is no viewport.
@@ -18,14 +20,38 @@ There are various ways to try and read the size of the viewport/window.
 
 [^fn1]: When specs talk about _“the Viewport”_, they mean [the Layout Viewport](./layout-viewport.md).
 
+### Findings
+
+💡 These findings are a textual representation of the [test results table](https://goo.gle/interop-2022-viewport-testresults).
+
+In all browsers the `innerHeight` and `innerWidth` behave as defined/expected.
+
+When pinch-zooming in, WebKit adjusts these values as you pich-zoom in on the page, taking over the `width`/`height` of the [Visual Viewport](./visual-viewport.md)
+
 ## `window.outerWidth` and `window.outerHeight`
 
+### Definition
+
 `window.outerWidth` and `window.outerHeight` are defined in the [CSSOM View Module](https://drafts.csswg.org/cssom-view/#dom-window-outerwidth):
 
 > The `outerWidth` attribute must return the width of the client window. If there is no client window this attribute must return zero.
 > 
 > The `outerHeight` attribute must return the height of the client window. If there is no client window this attribute must return zero.
 
+### Findings
+
+💡 These findings are a textual representation of the [test results table](https://goo.gle/interop-2022-viewport-testresults).
+
+On Desktop all is pretty straigthforward and the `outerHeight` equals the [`innerHeight`](#windowinnerwidth-and-windowinnerheight) + the size of the browser’s top and bottom bars.
+
+On Mobile it’s a different story:
+
+- Only Safari on iOS and Chrome on iOS see the `outerHeight` as the _(unzoomed [^fn1])_ `innerHeight` + size of the browser’s chrome. Essentially this equals the screen’s `height` here, as apps run fullscreen on such devices.
+- Most other mobile browsers use the values from `innerHeight` as the value for its `outerHeight`. When the UA UI Toolbars retract, both sizes get adjusted. This seems wrong.
+- Firefox on Android does something special where the `outerHeight` is a value somewhere in between the [Small Viewport](./viewport-units.md#the-small-viewport) _(`innerHeight` when UA UI is expanded)_ and [Large Viewport](./viewport-units.md#the-large-viewport) _(`innerHeight` when UA UI is retracted)_.
+
+[^fn1]: “unzoomed” because `innerHeight` resizes in these browsers. See the section covering [`innerHeight`](#windowinnerwidth-and-windowinnerheight)
+
 ## `document.documentElement.clientWidth` and `document.documentElement.clientHeight`
 
 `document.documentElement.clientWidth` and `document.documentElement.clientHeight` can be used to measure the [ICB](./icb.md). This due to [an exception in the definition of `clientWidth`/`clientWidth`](https://www.w3.org/TR/cssom-view-1/#dom-element-clientwidth):