feat(#24): custom layouts for sessions

fix(#23): sort characters by campaign

feat(#18): add theme variables

fix(#22): use cards for campaigns

fix: use sticky property for header

fix(#21): use cards for backgrounds

closes #21

feat(#16): add game mode taxonomy

Merge pull request #15 from sekthor/feat/toc

feat(#7): add table of contents

fix: reduce border radius

feat: fixed header with blured transparancy