TUI - refactor CSS in governance operations

1. Instead of using percentages in the grid columns, use the proper fr, thus replacing: grid-columns: 20% 11% 35% 20% 14%; to this: grid-columns: 1fr 2fr 1fr 2fr; This property will also be used for columns that never change.

2. Refactor of giving colours to elements, start using CSS variables. Start using a predefined text colour system instead of RGB values.