These settings apply when you are using 2D mode for your current portal (the one you are currently setting up).
Options include:
Theme - choose from a pre-set theme for colors and design
Header Background Color
Primary Brand Color
Background Color
Background Text Color
Button Style - Rounded, Square or Pill
Card Style - Rounded, Square or Pill
Padding - Standard or Minimal
Font
Preview - shows a preview of your style and theme selections
Agenda Color - checking this box will use the colors assigned in the agenda