191872 2018-11-20 17:50:17 -0800 WkWebView does not set the `env(safe-area-inset-*)` CSS variables until some arbitrary time after page load. 2026-02-18 19:41:48 -0800 1 1 1 Unclassified WebKit WebKit Misc. Other iPhone / iPad iOS 12 NEW InRadar P2 Major --- 1 ccorcos webkit-unassigned brian.arpie carlosj-webkit-bugzilla fotis.papadogeorgopoulos kainosnoema makhlonov simon.fraser super.xhmm thorton version.ru webkit-bug-importer oldest_to_newest 1480642 0 ccorcos 2018-11-20 17:50:17 -0800 This app linked to below shows an html webpage inside a WKWebView that measures the env(safe-area-inset-*) css variables. You will notice that these variables are not available on the initial load of the app, or after the window load event, or the document DOMContentLoaded event. These CSS variables only seem to be available at some arbitrary time after the app is loaded. However, if you open up the same webpage (http://localhost:8000/) in iOS Safari in landscape mode and hit refresh, you'll notice that these CSS variables are available at initial load time. https://github.com/ccorcos/WkWebView-Safe-Area-Inset-Bug Please try it out and give it a spin. ``` git clone https://github.com/ccorcos/WkWebView-Safe-Area-Inset-Bug cd WkWebView-Safe-Area-Inset-Bug # Server the index.html file python -m SimpleHTTPServer 8000 # Open Xcode and run the app. open WebViewBug.xcodeproj ``` 1480651 1 webkit-bug-importer 2018-11-20 19:01:59 -0800 <rdar://problem/46193462> 1644888 2 brian.arpie 2020-04-23 11:57:27 -0700 Any update on this bug? I can reproduce on iOS 13. 1921685 3 super.xhmm 2022-12-23 09:47:39 -0800 Same problem here for ios 16, this issue caused the fixed bottom button had a sudden jump when page doms were some complicated, because the first render safa-area-inset-bottom was zero, next render it become 34px, but when page was simple, no jump happened 1921686 4 super.xhmm 2022-12-23 09:47:57 -0800 Same problem here for ios 16, this issue caused the fixed bottom button had a sudden jump when page doms were some complicated, because the first render safa-area-inset-bottom was zero, next render it become 34px, but when page was simple, no jump happened 1929105 5 kainosnoema 2023-01-27 17:53:15 -0800 We're also struggling with this bug still in iOS 16 still. All of the safe-area-inset-* CSS env vars are zero until shortly after the webview is initialized sub-second, but noticeable). It happens both when first launching an app into a WKWebView and also restoring after the app's been suspended. Because it's non-deterministic, it's very hard to work around manually.