Fix broken scrollbars
Fix broken scrollbars

Somehow NW.js/Chromium doesn't like overflow:hidden being set on the
document body anymore and the parent wrapper element of the main content
element needs to have this property set.

streamlink/streamlink-twitch-gui,bastimeyer/livestreamer-twitch-gui,bastimeyer/livestreamer-twitch-gui,streamlink/streamlink-twitch-gui,chhe/livestreamer-twitch-gui,chhe/livestreamer-twitch-gui,streamlink/streamlink-twitch-gui,chhe/livestreamer-twitch-gui,bastimeyer/livestreamer-twitch-gui