Remove unnecessary scrollbars

The margin property can escape the parent node and move it alongside
its child. This happens with singlePage div and the body, resulting in
scrollbars appearing as the body has the size of the viewport but
does not align with it. This phenomenon can be always observed
in the vertical axis and it can also be observed in the horizontal axis
when the viewport it’s not wide enough (mostly in mobile).

Using paddings prevents this “extra space” from scraping and displacing
the body.

Also, the value 100vw does not take into account the space taken by the
vertical scrollbar, thus making the body wider than the actual viewport,
producing a horizontal scrollbar.