Bug 193198

Summary: Wrong root element dimensions when page with overflowing elements being scaled down in split screen
Product: WebKit Reporter: Rikumi Yu <riku.mi>
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 12   
Hardware: Mac   
OS: macOS 10.14   
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Rikumi Yu
Reported 2019-01-07 08:07:24 PST
Created attachment 358497 [details] Screenshot Steps to reproduce: 1. Construct a page with at least one element overflowing viewport: ``` <html><head><style> body { width: 100%; margin: 10px; } body::before { content: ''; position: absolute; width: 100%; height: 100%; background: #777; } </style></head><body></body></html> ``` 2. On Safari 12, go to Safari -> Preferences -> Websites -> Page Zoom, and scale the current page down (50% is best to reproduce the bug). 3. Set Safari to fullscreen. 4. Open the constructed page. 5. Split the screen with another window (or the devtools). 6. Drag the separator to give the Safari window enough width (>= 1100pt). 7. Drag the separator again to reduce the width (< 1100pt). 8. The page turns into bad layout, where the root element is half the width of viewport (when the zoom factor is 50%). Since tons of public sites does not use `overflow:hidden` for `<html>`, this bug can be easily reproduced.
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2019-01-07 08:07 PST, Rikumi Yu 		no flags
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Radar WebKit Bug Importer
Comment 1 2019-01-07 12:47:48 PST
<rdar://problem/47093395>
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