/* --- 1. 基础沉浸设定 --- */
html, body {
    margin: 0; padding: 0;
    background-color: #020203; /* 极致的黑，留给霓虹灯发光 */
    color: #fff;
    font-family: 'Manrope', sans-serif;
    overscroll-behavior: none; /* 杀死 iOS 的回弹 */
}

/* 动态环境光层 */
.ambient-bg {
    position: fixed; top: 0; left: 0; width: 100vw; height: 100vh;
    z-index: 1; pointer-events: none;
    box-shadow: inset 0 0 200px rgba(0,0,0,0);
    transition: box-shadow 0.8s cubic-bezier(0.2, 0.8, 0.2, 1);
}


/* --- 专属的滑动引导线 --- */
.scroll-indicator {
    position: absolute;
    bottom: 3rem; /* 和两边的数据保持在同一水平线上 */
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.8rem;
    z-index: 100;
    pointer-events: none;
    /* 极其平滑的消散动画 */
    transition: opacity 1s ease-out, filter 1s ease-out; 
}

.indicator-text {
    font-size: 1rem; /* 极致的小 */
    letter-spacing: 0.4em;
    color: rgba(255, 255, 255, 0.8);
}

.indicator-line {
    width: 1px; /* 极细的线 */
    height: 40px;
    background-color: rgba(255, 255, 255, 0.1);
    overflow: hidden;
    position: relative;
}

/* 这根纯白色的线会像水滴一样不断坠落 */
.line-progress {
    width: 100%;
    height: 100%;
    background-color: #e5feff;
    position: absolute;
    top: -100%;
    animation: scrollDrop 2s cubic-bezier(0.77, 0, 0.175, 1) infinite;
}

@keyframes scrollDrop {
    0% { top: -100%; }
    50% { top: 0; }
    100% { top: 100%; }
}
/* --- 2. 悬浮组件 --- */
.btn-back {
    position: fixed;
    top: 2rem;
    left: 2rem;
    /* 💡 1. 核心：启动 Flex 引擎 */
    display: flex;
    align-items: center;
    gap: 0.5rem; /* 初始挡位间距 */
    
    color: #fff;
    text-decoration: none;
    font-weight: 600;
    font-size: 1rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
    padding-bottom: 0.2rem; 
    z-index: 100;
    opacity: 0.8;

    transition: all 0.4s cubic-bezier(0.2, 0.8, 0.2, 1); 
}

.btn-back:hover { 
    opacity: 1; 
    gap: 1.2rem; 
    border-bottom: 1px solid #fff;
}


.back-arrow {
    transition: transform 0.4s cubic-bezier(0.2, 0.8, 0.2, 1);
}

.hero-fixed {
    position: fixed; top: 50%; left: 50%; transform: translate(-50%, -50%);
    z-index: 20; text-align: center; pointer-events: none;
    transition: opacity 1s ease;
}

.hero-title {
    font-family: 'Playfair Display', serif;
    font-size: clamp(3rem, 10vw, 8rem);
    letter-spacing: 0.1em; margin: 0; color: #fff;
    animation: neonPulse 3s infinite alternate;
}

.hero-subtitle {
    font-size: 1rem; letter-spacing: 0.3em; color: #666; margin-top: 1rem;
}

@keyframes neonPulse {
    0% { text-shadow: 0 0 10px rgba(255, 255, 255, 0.1); }
    100% { text-shadow: 0 0 30px rgba(0, 240, 255, 0.2); }
}

/* --- 3. 核心 3D  --- */
.scroll-proxy {
    
    height: 12000px; 
}

.camera-viewport {
    position: fixed; top: 0; left: 0; width: 100vw; height: 100vh;
    z-index: 10;
    perspective: 1000px; 
    overflow: hidden;
    pointer-events: none; 
}

.tunnel-scene {
    position: absolute; top: 0; left: 0; width: 100%; height: 100%;
    transform-style: preserve-3d; 

}

/* --- 4. tunnel --- */
.tunnel-item {
    position: absolute;
    top: 50%; left: 50%;
    transform: translate(-50%, -50%) translateZ(calc(var(--z) * 1px));
    width: 65vw;
    max-width: 900px;
    opacity: 0; 
    transition: opacity 0.5s ease;
     will-change: transform, opacity, filter; /* 提前唤醒 GPU 分配显存 */
}
.tunnel-item.is-portrait {
   
    width: 45vw; 
    max-width: 600px; 
}

.image-wrapper {
    width: 100%; border-radius: 10px; overflow: hidden;
   
    box-shadow: 0 50px 100px rgba(0,0,0,0.9); 
}

.image-wrapper img {
    width: 100%; height: auto; display: block;
    
    filter: contrast(1.1) brightness(0.9);
}


.tunnel-item.active .red-neon { box-shadow: 0 20px 150px rgba(0, 240, 255, 0.2); }
.tunnel-item.active .cyan-neon { box-shadow: 0 20px 150px rgba(0, 240, 255, 0.3); }
.tunnel-item.active .purple-neon { box-shadow: 0 20px 150px rgba(184, 184, 184, 0.3); }

.meta {
    position: absolute; bottom: -3rem; right: 0;
    display: flex; align-items: baseline; gap: 1rem;
    color: rgba(255,255,255,0.4);
}
.meta span { font-family: 'Playfair Display', serif; font-size: 2rem; font-style: italic; color: #fff;}
.meta p { font-size: 0.6rem; letter-spacing: 0.3em; }


@media (max-width: 768px) {
    .tunnel-item { width: 90vw; }
    .hero-title { font-size: 3.5rem; }
    .camera-viewport {
        perspective: 800px; 
    }
    .tunnel-item.is-portrait {
        width: 70vw; 
    }
}