/* 滚动淡入动画 */
.reveal { opacity: 0; transform: translateY(26px); transition: opacity .7s ease, transform .7s ease; }
.reveal.in { opacity: 1; transform: none; }
.reveal:nth-child(2) { transition-delay: .08s; }
.reveal:nth-child(3) { transition-delay: .16s; }
.reveal:nth-child(4) { transition-delay: .24s; }