Bug 250621

Summary: Initial container block (ICB) resizes in in-app browsers when scrolling
Product: WebKit Reporter: Rogier de Ruijter <imbashenk>
Component: Layout and RenderingAssignee: Nobody <webkit-unassigned>
Status: NEW ---    
Severity: Normal CC: bfulgham, simon.fraser, webkit-bug-importer, zalan
Priority: P2 Keywords: InRadar
Version: Safari 16   
Hardware: iPhone / iPad   
OS: iOS 16   
Attachments:
Description Flags
Video of the ICB changing none

Description Rogier de Ruijter 2023-01-14 07:08:40 PST 
Created attachment 464498 [details]
Video of the ICB changing

When this page: https://interop-2022-viewport.netlify.app is opened on an in-app browser on iOS. You can see (also see video in attachment) that when you start scrolling the ICB (the red line) changes size. This is a problem for view height units (vh, svh) since they will resize and your scroll position on the page changes.

The preferred behaviour would be that the ICB doesn't change like on Safari mobile.
Comment 1 Radar WebKit Bug Importer 2023-01-14 07:12:10 PST 
<rdar://problem/104260623>