ios8 viewport - not 100%

After updating my iPad to iOS 8.0.2 I saw that the initial size of the viewport (both: width & height) are not 100%.

There's a space gap on the right and at the bottom.

I did notice too that after closing the other browser tab in Safari, the layout of the viewport refreshed and the gaps were gone.

iOS8_viewport.jpg

ios8 viewport - not 100%