:root{
  --radius-xs:4px;    /* hairline tags, table chrome */
  --radius-sm:6px;    /* form inputs */
  --radius-md:8px;    /* compact cards, alerts */
  --radius-lg:12px;   /* pricing + feature cards */
  --radius-xl:16px;   /* dashboard mockup chrome */
  --radius-pill:9999px; /* every button and tag pill */
}