The banner readability could be slightly improved using constants[1] (and prefixing with _ to hide it from list output).

  # print all available commands by default
  default:
    @just --list

  ci:
    @just _banner yarn install
    yarn install
    @just _banner tsc
    tsc --noEmit
    @just _banner lint
    eslint src
    prettier --check src
    @just _banner vitest
    vitest --run
    @just _banner done!

  _banner *ARGS:
    @printf '{{BOLD + WHITE + BG_GREEN}}[%s] %-72s{{NORMAL}}\n' "$(date +%H:%M:%S)" "{{ARGS}}"

[1]: https://just.systems/man/en/constants.html