[UHN-MA-21] Use relative length units for base styling

[mankitkong]

• Explore into using relative length units to define certain css params (e.g. margins/padding width/height)
  • This helps the app to render correctly on different dimensions (e.g. difference in sizes of iPhones and Android phones)
  • This IS NOT for tablet vs phone comparisons (these should use media queries)

[mankitkong]

Tai just tested the app on his device LG K4 2017 (https://www.gsmarena.com/lg_k4_(2017)-8489.php) and he is seeing overlapping components.