Use Bulma helpers whenever possible instead of custom styled components.
This pull request replaces primarily color definitions, spacing and flex instructions.
Fix annotate overflow: Total div size was smaller than minimum size of individual children (+ margin).
Fix doubled spacing in code content views: Spacing duplicates through .panel-block as default for styling, various containers and inner syntax highlighter definition. Unfortunately, the latter is not easy to change, since it is also used with inline syntax highlighter.
