.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 1s var(--ease-apple), transform 1s var(--ease-apple);
}
.beta-option-flag img {
  width: 16px;
  height: auto;
  /* 保持宽高比 */
  vertical-align: middle;
}
.reveal.in {
  opacity: 1;
  transform: translateY(0);
}

.reveal-lines span {
  display: block;
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.8s var(--ease-apple), transform 0.8s var(--ease-apple);
}

.reveal-lines.in span {
  opacity: 1;
  transform: translateY(0);
}

.why-reveal {
  --why-img-progress: 0;
  --why-text-progress: 0;
}

.why-reveal .why-hero-img {
  opacity: var(--why-img-progress);
  transform: translateY(calc(80px * (1 - var(--why-img-progress)))) scale(calc(1.05 - (0.05 * var(--why-img-progress))));
}

.why-reveal .why-text {
  opacity: var(--why-text-progress);
  transform: translateY(calc(20px * (1 - var(--why-text-progress))));
}

.scroll-unlock {
  opacity: var(--progress, 0);
  transform: translateY(calc(24px * (1 - var(--progress, 0))));
  transition: opacity 0.2s linear, transform 0.2s linear;
}

.feature-card {
  transition: transform 0.6s var(--ease-apple), box-shadow 0.6s var(--ease-apple);
}

.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 16px 40px rgba(0,0,0,0.12);
}

@media (prefers-reduced-motion: reduce) {
  .reveal,
  .reveal-lines span {
    transform: translateY(8px);
    transition-duration: 0.35s;
  }

  .scroll-unlock {
    transform: translateY(calc(10px * (1 - var(--progress, 0))));
    transition-duration: 0.12s;
  }

  .why-reveal .why-hero-img {
    transform: translateY(calc(32px * (1 - var(--why-img-progress)))) scale(calc(1.02 - (0.02 * var(--why-img-progress))));
  }

  .why-reveal .why-text {
    transform: translateY(calc(10px * (1 - var(--why-text-progress))));
  }
}