Added ellipsis for long usernames within header/welcome banner
Fixed content overflow within header by adding max height to the appropriate media queries (original media queries weren't targeting the corresponding devices because they did not contain and (-webkit-min-device-pixel-ratio: <ratio here>) after min/max width/height. Also made header scrollable.
and (-webkit-min-device-pixel-ratio: <ratio here>)after min/max width/height. Also made header scrollable.