{ ... }:
{
  # Use CET/CEST timezone.
  time.timeZone = "Europe/Berlin";

  # Use local time so Windows dual boots don't reset on summertime.
  time.hardwareClockInLocalTime = true;

  # Fall back to American (simple) English.
  i18n.defaultLocale = "en_US.UTF-8";

  # Use en_DK.UTF-8 because it has:
  # - Euro monetary
  # - Decimal period numeric
  # - ISO 8601 date
  # - 24h time
  i18n.extraLocaleSettings = {
    LC_ADDRESS = "en_DK.UTF-8";
    LC_IDENTIFICATION = "en_DK.UTF-8";
    LC_MEASUREMENT = "en_DK.UTF-8";
    LC_MONETARY = "en_DK.UTF-8";
    LC_NAME = "en_DK.UTF-8";
    LC_NUMERIC = "en_DK.UTF-8";
    LC_PAPER = "en_DK.UTF-8";
    LC_TELEPHONE = "en_DK.UTF-8";
    LC_TIME = "en_DK.UTF-8";
  };

  # Use "US International Alt Gr. with Dead Keys".
  # This is handy because it has plenty of international variants on `AltGr + <key>`.
  console.keyMap = "us-acentos";
  services.xserver.xkb = {
    layout = "us";
    variant = "altgr-intl";
  };
}