:root {
  --danger-color: #dc2626;
  --border-color: #8e8e8e;

  /* Fallback for browsers without color-mix; overridden below to track the theme. */
  --divider-color: #e1e1e1;
}

/* Dividers are decorative, so they derive a faded tint of the themable border
   colour: subtle, but still tracks an organiser's palette. */
@supports (color: color-mix(in srgb, red, blue)) {
  :root {
    --divider-color: color-mix(in srgb, var(--custom-border-color, #8e8e8e) 30%, transparent);
  }
}