@layer layout {
  /* A tinted page section whose background runs edge to edge, even inside the 1600px
     .main-content-container, while its content keeps the container's width. The fill of a
     border-image paints over the element's own background, so it also covers the legacy
     white section backgrounds. */
  .band {
    border-image: conic-gradient(var(--color-band) 0 0) fill 0 // 0 100vw;
  }
}