For screen width around 768px (iPad portrait) and 736px (iPhone 7 Plus landscape), the page won't spread across the entire screen: the white column stays on the right.
The problem is the use of rem for media query. Safari interprets rem in the media query as the base font size set in CSS, not as the browser's default font-size.
For screen width around 768px (iPad portrait) and 736px (iPhone 7 Plus landscape), the page won't spread across the entire screen: the white column stays on the right.