I have put this tag in the head of a webpage:
For s
Viewport width is different in may devices. iOS has 320, android has 360 in portrait mode. Landscape mode - it depends on which device you have, you will get different different width.
Best way to make website optimized for mobile is set width=device-width. If you don't set initial-scale=1.0 - iOs will zoom in (enlarge) screen when changing device rotation.
This meta is all you needed.
And if you wanted to disable the zoom feature, set user-scalable=no
Do not hard code width property as it will set same width for portrait and landscape modes - which is very unpleasing user experience.
Best documented: https://developer.apple.com/library/ios/documentation/AppleApplications/Reference/SafariWebContent/UsingtheViewport/UsingtheViewport.html
About iOs 7 Moreover I would say - dont worry about iOS7 as of now. It has so many bugs. Read here: http://www.sencha.com/blog/the-html5-scorecard-the-good-the-bad-and-the-ugly-in-ios7/