/* UI components (task-i18n-toggle): the language switch and the
 * chapter-7 stack marquee. Everything animated respects
 * prefers-reduced-motion; the switch itself is motion-free.
 */

/* Language switch — fixed top-right corner, above the rail. ------------- */

.lang-switch {
  position: fixed;
  top: var(--space-4);
  right: var(--space-4);
  z-index: 20;
  display: inline-flex;
  border: 1px solid var(--line);
  border-radius: 999px;
  overflow: hidden;
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: blur(6px);
}

.lang-btn {
  appearance: none;
  border: 0;
  background: transparent;
  color: var(--ink-dim);
  font-family: var(--font-mono);
  font-size: var(--step--1);
  letter-spacing: 0.08em;
  padding: var(--space-1) var(--space-3);
  cursor: pointer;
}

.lang-btn[aria-pressed="true"] {
  background: var(--accent);
  color: var(--accent-ink);
  font-weight: 700;
}

.lang-btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: -2px;
}

/* Chapter 7 — stack marquee (the toolbox). ------------------------------ */

.stack-kicker {
  color: var(--ink-dim);
  font-family: var(--font-mono);
  font-size: var(--step--1);
  letter-spacing: 0.35em;
  text-transform: uppercase;
  text-align: center;
  margin-bottom: var(--space-4);
}

.stack-marquee {
  overflow: hidden;
  max-width: 100%;
  border-block: 1px solid var(--line);
  padding-block: var(--space-3);
  /* fade the edges so the loop reads as endless, not cut */
  mask-image: linear-gradient(90deg, transparent, #000 8%, #000 92%, transparent);
  -webkit-mask-image: linear-gradient(90deg, transparent, #000 8%, #000 92%, transparent);
}

.stack-track {
  display: inline-flex;
  gap: var(--space-5);
  width: max-content;
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: var(--step-0);
  white-space: nowrap;
}

.stack-track span::after {
  content: "·";
  color: var(--accent);
  margin-left: var(--space-5);
}

@media (prefers-reduced-motion: no-preference) {
  .stack-track {
    animation: stack-scroll 36s linear infinite;
  }
}

@keyframes stack-scroll {
  from { transform: translateX(0); }
  to   { transform: translateX(-50%); }
}

@media (prefers-reduced-motion: reduce) {
  .stack-track {
    flex-wrap: wrap;
    white-space: normal;
    justify-content: center;
    row-gap: var(--space-2);
  }

  /* The duplicated half exists for the seamless loop; hide it when static. */
  .stack-track span:nth-child(n + 19) {
    display: none;
  }
}