/* Page structure. Mobile = one column, scrolls as a page.
 * ≥64em = two columns: sticky deck on the left, independently scrolling library on the right. */
@layer layout {
  .app {
    min-height: 100dvh;
    display: grid;
    grid-template-rows: auto 1fr auto;
  }

  .topbar {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--space-2) var(--space-4);
    width: 100%;
    max-width: 90rem;
    margin-inline: auto;
    padding: max(var(--space-3), env(safe-area-inset-top)) var(--space-4) var(--space-2);
  }
  .topbar__stats {
    flex: 1 1 auto;
    min-width: 0;
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    color: var(--color-text-3);
    letter-spacing: 0.02em;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }
  .topbar__stats:empty { display: none; }
  .topbar__actions {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    margin-inline-start: auto;
  }

  .app__main {
    width: 100%;
    max-width: 90rem;
    margin-inline: auto;
    padding: var(--space-3) var(--space-4) var(--space-6);
    display: grid;
    gap: var(--space-5);
    align-content: start;
  }

  .deck {
    display: grid;
    gap: var(--space-3);
    min-width: 0;
  }

  .library {
    display: grid;
    gap: var(--space-3);
    min-width: 0;
    align-content: start;
    container-type: inline-size;
    container-name: library;
  }

  .footer {
    padding: var(--space-4) var(--space-4) max(var(--space-4), env(safe-area-inset-bottom));
    border-top: 1px solid var(--color-border);
    text-align: center;
    font-size: var(--text-xs);
    color: var(--color-text-3);
  }
  .footer__hint { margin-top: var(--space-1); }

  @media (min-width: 48em) {
    .topbar { padding-inline: var(--space-5); }
    .app__main { padding-inline: var(--space-5); }
  }

  @media (min-width: 64em) {
    .app__main {
      grid-template-columns: minmax(0, 11fr) minmax(24rem, 9fr);
      gap: var(--space-6);
      align-items: start;
      padding-block: var(--space-4) var(--space-6);
    }
    .library {
      max-height: calc(100dvh - 6.5rem);
      grid-template-rows: auto auto auto minmax(0, 1fr) auto auto;
    }
    .library .tracks {
      overflow-y: auto;
      scrollbar-gutter: stable;
      padding-inline-end: var(--space-1);
      scrollbar-width: thin;
      scrollbar-color: var(--color-border-strong) transparent;
    }
  }

  @media (min-width: 64em) and (min-height: 46em) {
    .deck { position: sticky; top: var(--space-4); }
  }

  @media (min-width: 80em) {
    .topbar, .app__main { padding-inline: var(--space-6); }
  }
}