/* 淡入动画：从下方升起 + 透明度 0 → 1 */
.fade-in-up {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.fade-in-up.fade-in-visible {
    opacity: 1;
    transform: translateY(0);
}

/* 可选延迟工具类 */
.delay-100 { transition-delay: 0.1s; }
.delay-200 { transition-delay: 0.2s; }
.delay-300 { transition-delay: 0.3s; }
.delay-400 { transition-delay: 0.4s; }
.delay-500 { transition-delay: 0.5s; }