@media (max-width: 751px) {
  /* Pin the page only when the frame that hands scrolling to main exists;
     bespoke bundles without it keep native document scrolling. */
  .story-page:has(> .page > main),
  .story-page:has(> .story-page__frame > main) {
    position: fixed;
    inset: 0;
    width: 100%;
    height: 100dvh;
    min-height: 0;
    overflow: hidden;
  }

  .story-page > .page,
  .story-page > .story-page__frame {
    display: grid;
    height: 100%;
    min-height: 0;
    grid-template-rows: auto minmax(0, 1fr);
    overflow: hidden;
  }

  .story-page > .page > .masthead,
  .story-page > .story-page__frame > .masthead {
    min-width: 0;
  }

  .story-page > .page > main,
  .story-page > .story-page__frame > main {
    min-height: 0;
    overflow-x: hidden;
    overflow-y: auto;
    overscroll-behavior-y: contain;
  }

  .story-page .reaction-bar {
    min-height: 0;
  }
}