/* ==========================================
   CSS变量 - 配色 & 动画系统
   ========================================== */
:root {
    /* 配色 */
    --color-bg-primary: #000000;
    --color-text-primary: #ffffff;
    --color-text-secondary: #cccccc;
    --color-text-muted: #888888;
    --color-accent: #666666;

    /* 缓动曲线 - 丝滑动效 */
    --ease-smooth: cubic-bezier(0.4, 0, 0.2, 1);
    --ease-out: cubic-bezier(0, 0, 0.2, 1);
    --ease-in-out: cubic-bezier(0.65, 0, 0.35, 1);
    --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
    --ease-expo: cubic-bezier(0.16, 1, 0.3, 1);

    /* 时长 */
    --dur-fast: 0.2s;
    --dur-normal: 0.4s;
    --dur-slow: 0.6s;
    --dur-slower: 0.8s;
    --dur-glacial: 1.2s;
}

/* ==========================================
   Reset & 基础样式
   ========================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    scroll-snap-type: y mandatory;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB",
                 "Microsoft YaHei", "Segoe UI", Roboto, sans-serif;
    background: var(--color-bg-primary);
    color: var(--color-text-primary);
    overflow-x: hidden;
    min-height: 100vh;
}

/* ==========================================
   导航栏
   ========================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(0, 0, 0, 0.75);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    transition: background var(--dur-slow) var(--ease-smooth);
}

.nav-container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 1.5rem 2.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    display: flex;
    align-items: center;
}

.nav-logo img {
    height: auto;
    width: 150px;
    display: block;
    object-fit: contain;
}

/* 汉堡菜单按钮 — 桌面端隐藏 */
.hamburger {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
    z-index: 1001;
}

.hamburger span {
    display: block;
    width: 22px;
    height: 1.5px;
    background: var(--color-text-primary);
    border-radius: 1px;
    transition: all var(--dur-normal) var(--ease-smooth);
}

/* 汉堡菜单激活态 */
.hamburger.active span:nth-child(1) {
    transform: translateY(6.5px) rotate(45deg);
}

.hamburger.active span:nth-child(2) {
    opacity: 0;
}

.hamburger.active span:nth-child(3) {
    transform: translateY(-6.5px) rotate(-45deg);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 3rem;
}

.nav-menu > li > a {
    color: var(--color-text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    letter-spacing: 0.15em;
    transition: color var(--dur-normal) var(--ease-smooth);
    position: relative;
    padding: 0.3rem 0;
}

.nav-menu > li > a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    width: 0;
    height: 1px;
    background: var(--color-text-primary);
    transition: all var(--dur-normal) var(--ease-smooth);
    transform: translateX(-50%);
}

.nav-menu > li > a:hover {
    color: var(--color-text-primary);
}

.nav-menu > li > a:hover::after {
    width: 100%;
}

/* 当前激活页导航高亮 */
.nav-menu > li > a.active {
    color: var(--color-text-primary);
}

.nav-menu > li > a.active::after {
    width: 100%;
}

/* ==========================================
   产品下拉菜单 — 优雅展开
   ========================================== */
.nav-dropdown {
    position: relative;
}

.dropdown-toggle {
    cursor: default;
    user-select: none;
}

.dropdown-menu {
    position: absolute;
    top: calc(100% + 24px);
    left: 50%;
    transform: translateX(-50%) scaleY(0.6);
    transform-origin: top center;
    background: rgba(6, 6, 6, 0.98);
    backdrop-filter: blur(30px);
    -webkit-backdrop-filter: blur(30px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 8px;
    padding: 0.5rem 0;
    min-width: 160px;
    list-style: none;
    opacity: 0;
    visibility: hidden;
    transition:
        opacity var(--dur-fast) var(--ease-smooth),
        transform var(--dur-normal) var(--ease-expo),
        visibility 0s var(--dur-normal);
    box-shadow:
        0 0 20px rgba(255, 255, 255, 0.08),
        0 0 60px rgba(255, 255, 255, 0.03),
        0 12px 40px rgba(0, 0, 0, 0.5),
        inset 0 1px 0 rgba(255, 255, 255, 0.08);
}

.nav-dropdown:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) scaleY(1);
    transition:
        opacity var(--dur-fast) var(--ease-smooth),
        transform var(--dur-normal) var(--ease-expo),
        visibility 0s 0s;
}

/* 菜单项逐行淡入 */
.dropdown-menu li {
    opacity: 0;
    transform: translateY(-4px);
}

.nav-dropdown:hover .dropdown-menu li {
    animation: dropItemIn 0.35s var(--ease-out) forwards;
}

.nav-dropdown:hover .dropdown-menu li:nth-child(1) { animation-delay: 0.02s; }
.nav-dropdown:hover .dropdown-menu li:nth-child(2) { animation-delay: 0.08s; }
.nav-dropdown:hover .dropdown-menu li:nth-child(3) { animation-delay: 0.14s; }
.nav-dropdown:hover .dropdown-menu li:nth-child(4) { animation-delay: 0.20s; }

@keyframes dropItemIn {
    from {
        opacity: 0;
        transform: translateY(-4px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.dropdown-menu a {
    display: block;
    padding: 0.55rem 1.4rem;
    color: var(--color-text-secondary);
    font-size: 0.85rem;
    letter-spacing: 0.08em;
    text-decoration: none;
    transition: color var(--dur-fast) var(--ease-smooth),
                background var(--dur-fast) var(--ease-smooth);
    white-space: nowrap;
}

.dropdown-menu a:hover {
    color: var(--color-text-primary);
    background: rgba(255, 255, 255, 0.05);
}

.dropdown-menu a::after {
    display: none;
}

/* ==========================================
   Slide 系统 - PPT式全屏页
   ========================================== */
.slide {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
    scroll-snap-align: start;
}

.slide-content {
    text-align: center;
    max-width: 800px;
    width: 100%;
    padding: 6rem 2rem;
    position: relative;
    z-index: 2;
    /* 默认隐藏 → JS 触发入场动画 */
    opacity: 0;
    transform: translateY(40px);
    transition: opacity var(--dur-slower) var(--ease-expo),
                transform var(--dur-slower) var(--ease-expo);
}

.slide-content.visible {
    opacity: 1;
    transform: translateY(0);
}

/* 通用文字标签 */
.slide-label {
    display: block;
    font-size: 0.72rem;
    letter-spacing: 0.35em;
    color: var(--color-text-muted);
    margin-bottom: 1.8rem;
    font-family: 'Montserrat', 'Inter', sans-serif;
    opacity: 0;
    transform: translateY(12px);
    transition: opacity var(--dur-slow) var(--ease-out) 0.1s,
                transform var(--dur-slow) var(--ease-out) 0.1s;
}

.slide-content.visible .slide-label {
    opacity: 1;
    transform: translateY(0);
}

/* 通用标题 */
.slide-title {
    font-size: 2.6rem;
    font-weight: 200;
    letter-spacing: 0.2em;
    color: var(--color-text-primary);
    margin-bottom: 1.5rem;
    text-indent: 0.2em;
    opacity: 0;
    transform: translateY(16px);
    transition: opacity var(--dur-slow) var(--ease-out) 0.15s,
                transform var(--dur-slow) var(--ease-out) 0.15s;
}

.slide-content.visible .slide-title {
    opacity: 1;
    transform: translateY(0);
}

/* 通用描述 */
.slide-desc {
    font-size: 1.05rem;
    line-height: 2;
    color: var(--color-text-secondary);
    max-width: 560px;
    margin: 0 auto;
    font-weight: 300;
    opacity: 0;
    transform: translateY(12px);
    transition: opacity var(--dur-slow) var(--ease-out) 0.25s,
                transform var(--dur-slow) var(--ease-out) 0.25s;
}

.slide-content.visible .slide-desc {
    opacity: 1;
    transform: translateY(0);
}

/* 链接按钮 */
.slide-link {
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
    margin-top: 2.5rem;
    color: var(--color-text-primary);
    text-decoration: none;
    font-size: 0.95rem;
    letter-spacing: 0.12em;
    padding: 0.8rem 2.2rem;
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 100px;
    transition: all var(--dur-normal) var(--ease-smooth);
    opacity: 0;
    transform: translateY(12px);
}

.slide-content.visible .slide-link {
    opacity: 1;
    transform: translateY(0);
    transition: opacity var(--dur-slow) var(--ease-out) 0.35s,
                transform var(--dur-slow) var(--ease-out) 0.35s,
                background var(--dur-normal) var(--ease-smooth),
                border-color var(--dur-normal) var(--ease-smooth);
}

.slide-link:hover {
    background: rgba(255, 255, 255, 0.06);
    border-color: rgba(255, 255, 255, 0.4);
    gap: 0.9rem;
}

.slide-link .arrow {
    display: inline-block;
    transition: transform var(--dur-normal) var(--ease-spring);
}

.slide-link:hover .arrow {
    transform: translateX(4px);
}

/* ==========================================
   SCROLL 指示器 (通用，默认隐藏)
   ========================================== */
.scroll-indicator {
    position: absolute;
    bottom: 2.5rem;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.8rem;
    z-index: 3;
    opacity: 0;
    transition: opacity var(--dur-slower) var(--ease-out) 0.5s;
}

.slide-content.visible ~ .scroll-indicator,
.slide-content.visible + .scroll-indicator {
    opacity: 1;
}

.scroll-text {
    font-size: 0.65rem;
    letter-spacing: 0.45em;
    color: var(--color-text-muted);
    font-family: 'Montserrat', 'Inter', sans-serif;
}

.scroll-line {
    display: block;
    width: 1px;
    height: 50px;
    background: linear-gradient(to bottom,
        var(--color-text-muted) 0%,
        transparent 100%);
    animation: scrollPulse 2s ease-in-out infinite;
}

@keyframes scrollPulse {
    0%, 100% { opacity: 0.35; }
    50% { opacity: 1; }
}

/* ==========================================
   全局黑洞背景 (固定于视口后方)
   ========================================== */
.black-hole-bg {
    position: fixed;
    inset: 0;
    z-index: 0;
    pointer-events: none;
    display: flex;
    align-items: center;
    justify-content: center;
}

.black-hole {
    position: relative;
    width: 600px;
    height: 600px;
}

.event-horizon {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 180px;
    height: 180px;
    background: radial-gradient(circle at center,
        rgba(0, 0, 0, 1) 0%,
        rgba(20, 20, 20, 0.9) 40%,
        rgba(40, 40, 40, 0.6) 70%,
        transparent 100%);
    border-radius: 50%;
    box-shadow:
        inset 0 0 50px rgba(0, 0, 0, 0.8),
        0 0 100px rgba(0, 0, 0, 0.5);
    animation: pulse 4s ease-in-out infinite;
}

.accretion-disk {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 400px;
    height: 400px;
    border-radius: 50%;
    background: conic-gradient(
        from 0deg,
        transparent 0%,
        rgba(100, 100, 100, 0.1) 25%,
        rgba(150, 150, 150, 0.2) 50%,
        rgba(100, 100, 100, 0.1) 75%,
        transparent 100%
    );
    animation: rotate 20s linear infinite;
}

.disk-2 {
    width: 500px;
    height: 500px;
    opacity: 0.6;
    animation: rotate 30s linear infinite reverse;
}

.disk-3 {
    width: 350px;
    height: 350px;
    opacity: 0.4;
    animation: rotate 15s linear infinite;
}

@keyframes pulse {
    0%, 100% {
        transform: translate(-50%, -50%) scale(1);
        opacity: 1;
    }
    50% {
        transform: translate(-50%, -50%) scale(1.05);
        opacity: 0.9;
    }
}

@keyframes rotate {
    from { transform: translate(-50%, -50%) rotate(0deg); }
    to   { transform: translate(-50%, -50%) rotate(360deg); }
}

/* 品牌文字 - Slide 1 专属 */
.brand {
    margin-bottom: 5rem;
}

.brand-cn {
    font-size: 3.8rem;
    font-weight: 200;
    letter-spacing: 0.4em;
    margin-bottom: 1.5rem;
    color: var(--color-text-primary);
    text-shadow: 0 0 30px rgba(255, 255, 255, 0.1);
    text-indent: 0.4em;
    /* 入场动画由通用 .slide-title 控制 */
    opacity: 0;
    transform: translateY(20px);
    transition: opacity var(--dur-slow) var(--ease-out) 0.15s,
                transform var(--dur-slow) var(--ease-out) 0.15s;
}

.slide-content.visible .brand-cn {
    opacity: 1;
    transform: translateY(0);
}

.brand-divider {
    width: 40px;
    height: 1px;
    background: var(--color-accent);
    margin: 0 auto 1.5rem;
    opacity: 0;
    transform: scaleX(0);
    transition: opacity var(--dur-slow) var(--ease-out) 0.3s,
                transform var(--dur-slow) var(--ease-out) 0.3s;
}

.slide-content.visible .brand-divider {
    opacity: 0.6;
    transform: scaleX(1);
}

.brand-en {
    font-family: 'Montserrat', 'Inter', sans-serif;
    font-size: 1.4rem;
    font-weight: 300;
    letter-spacing: 0.8em;
    color: var(--color-text-secondary);
    margin-bottom: 2.5rem;
    text-indent: 0.8em;
    opacity: 0;
    transform: translateY(12px);
    transition: opacity var(--dur-slow) var(--ease-out) 0.25s,
                transform var(--dur-slow) var(--ease-out) 0.25s;
}

.slide-content.visible .brand-en {
    opacity: 1;
    transform: translateY(0);
}

.brand-tagline {
    font-size: 1.05rem;
    font-weight: 300;
    letter-spacing: 0.15em;
    color: var(--color-text-secondary);
    opacity: 0;
    transform: translateY(12px);
    transition: opacity var(--dur-slow) var(--ease-out) 0.35s,
                transform var(--dur-slow) var(--ease-out) 0.35s;
    line-height: 1.8;
}

.slide-content.visible .brand-tagline {
    opacity: 0.85;
    transform: translateY(0);
}

/* ==========================================
   Slide 2: 奕澄Markdown — 旋转吸积环
   ========================================== */
.slide-yicheng {
    border-top: 1px solid rgba(255, 255, 255, 0.04);
}

.product-logo {
    display: block;
    width: 100px;
    height: 100px;
    margin: 0 auto 2rem;
    object-fit: contain;
    opacity: 0;
    transform: translateY(16px) scale(0.9);
    transition: opacity var(--dur-slow) var(--ease-out) 0s,
                transform var(--dur-slow) var(--ease-out) 0s;
}

.slide-content.visible .product-logo {
    opacity: 1;
    transform: translateY(0) scale(1);
}

.slide-yicheng::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 450px;
    height: 450px;
    border-radius: 50%;
    border: 1px solid rgba(255, 255, 255, 0.03);
    transform: translate(-50%, -50%);
    animation: rotateRing 25s linear infinite;
    pointer-events: none;
    z-index: 0;
}

.slide-yicheng::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 350px;
    height: 350px;
    border-radius: 50%;
    background: conic-gradient(
        from 0deg,
        transparent 0%,
        rgba(90, 90, 110, 0.03) 30%,
        rgba(130, 130, 150, 0.06) 50%,
        rgba(90, 90, 110, 0.03) 70%,
        transparent 100%
    );
    transform: translate(-50%, -50%);
    animation: rotateRing 18s linear infinite reverse;
    pointer-events: none;
    z-index: 0;
}

@keyframes rotateRing {
    from { transform: translate(-50%, -50%) rotate(0deg); }
    to   { transform: translate(-50%, -50%) rotate(360deg); }
}

/* ==========================================
   全局轨道粒子 (每屏复用)
   ========================================== */
.particle-orbit {
    position: absolute;
    top: 50%;
    left: 50%;
    border-radius: 50%;
    pointer-events: none;
    z-index: 0;
}

.particle-orbit::before {
    content: '';
    position: absolute;
    top: -3px;
    left: 50%;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    transform: translateX(-50%);
}

/* 尺寸变体 */
.particle-orbit-xs {
    width: 200px;
    height: 200px;
    animation: rotateRing 7s linear infinite;
}

.particle-orbit-sm {
    width: 300px;
    height: 300px;
    animation: rotateRing 10s linear infinite reverse;
}

.particle-orbit-md {
    width: 400px;
    height: 400px;
    animation: rotateRing 14s linear infinite;
}

.particle-orbit-lg {
    width: 500px;
    height: 500px;
    animation: rotateRing 20s linear infinite reverse;
}

/* Slide 1 (Hero) — 亮白蓝色粒子 */
.slide-hero .particle-orbit::before {
    background: rgba(180, 200, 255, 0.35);
    box-shadow: 0 0 10px rgba(160, 190, 255, 0.5);
}

/* Slide 2 (奕澄) — 蓝紫色粒子 */
.slide-yicheng .particle-orbit::before {
    background: rgba(180, 170, 220, 0.3);
    box-shadow: 0 0 8px rgba(170, 160, 220, 0.4);
}

/* Slide 3 (公众号) — 暖琥珀色粒子 */
.slide-wechat .particle-orbit::before {
    background: rgba(220, 180, 140, 0.3);
    box-shadow: 0 0 8px rgba(210, 170, 120, 0.4);
}

/* Slide 4 (展示) — 柔和银白粒子 */
.slide-showcase .particle-orbit::before {
    background: rgba(200, 200, 210, 0.25);
    box-shadow: 0 0 6px rgba(190, 190, 200, 0.35);
}

/* ==========================================
   Slide 3: 暗而行舟公众号 — 脉动光环
   ========================================== */
.slide-wechat {
    border-top: 1px solid rgba(255, 255, 255, 0.04);
}

.slide-wechat::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 180px;
    height: 180px;
    border-radius: 50%;
    background: radial-gradient(circle,
        rgba(120, 110, 100, 0.08) 0%,
        rgba(80, 75, 70, 0.04) 40%,
        transparent 70%
    );
    transform: translate(-50%, -50%);
    animation: corePulse 5s ease-in-out infinite;
    pointer-events: none;
    z-index: 0;
}

.slide-wechat::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 380px;
    height: 380px;
    border-radius: 50%;
    border: 1px solid rgba(255, 255, 255, 0.025);
    transform: translate(-50%, -50%);
    animation: ringExpand 6s ease-in-out infinite;
    pointer-events: none;
    z-index: 0;
}

@keyframes corePulse {
    0%, 100% { transform: translate(-50%, -50%) scale(1); opacity: 0.6; }
    50%      { transform: translate(-50%, -50%) scale(1.4); opacity: 1; }
}

@keyframes ringExpand {
    0%, 100% { transform: translate(-50%, -50%) scale(0.9); opacity: 0.3; }
    50%      { transform: translate(-50%, -50%) scale(1.15); opacity: 0.8; }
}

.wechat-qr {
    margin-top: 2.5rem;
    display: flex;
    justify-content: center;
    opacity: 0;
    transform: translateY(12px);
    transition: opacity var(--dur-slow) var(--ease-out) 0.35s,
                transform var(--dur-slow) var(--ease-out) 0.35s;
}

.slide-content.visible .wechat-qr {
    opacity: 1;
    transform: translateY(0);
}

.qr-image {
    width: 180px;
    height: 180px;
    object-fit: contain;
    border-radius: 8px;
}

/* 公众号双logo并列 */
.wechat-logos {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1.5rem;
    margin-bottom: 2rem;
    opacity: 0;
    transform: translateY(12px);
    transition: opacity var(--dur-slow) var(--ease-out) 0.1s,
                transform var(--dur-slow) var(--ease-out) 0.1s;
}

.slide-content.visible .wechat-logos {
    opacity: 1;
    transform: translateY(0);
}

.gzh-logo {
    height: 48px;
    width: auto;
    object-fit: contain;
}

.gzh-logo-lg {
    height: 72px;
}

.logo-sep {
    font-size: 1.2rem;
    color: var(--color-text-muted);
    font-weight: 200;
}

/* ==========================================
   Slide 4: 用户展示 — 星尘背景 (最后一页，无SCROLL)
   ========================================== */
.slide-showcase {
    border-top: 1px solid rgba(255, 255, 255, 0.04);
}

.slide-showcase::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 320px;
    height: 320px;
    border-radius: 50%;
    border: 1px solid rgba(255, 255, 255, 0.02);
    transform: translate(-50%, -50%);
    animation: rotateRing 35s linear infinite;
    pointer-events: none;
    z-index: 0;
}

.slide-showcase::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 260px;
    height: 260px;
    border-radius: 50%;
    background: radial-gradient(circle,
        rgba(100, 100, 120, 0.04) 0%,
        rgba(80, 80, 100, 0.02) 30%,
        transparent 60%
    );
    transform: translate(-50%, -50%);
    animation: corePulse 7s ease-in-out infinite;
    pointer-events: none;
    z-index: 0;
}

.slide-showcase .slide-content {
    max-width: 1100px;
}

.showcase-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
    margin-top: 3.5rem;
    opacity: 0;
    transform: translateY(20px);
    transition: opacity var(--dur-slower) var(--ease-expo) 0.3s,
                transform var(--dur-slower) var(--ease-expo) 0.3s;
}

.slide-content.visible .showcase-grid {
    opacity: 1;
    transform: translateY(0);
}

.showcase-card {
    border: 1px solid rgba(255, 255, 255, 0.06);
    border-radius: 6px;
    overflow: hidden;
    transition: border-color var(--dur-fast) var(--ease-smooth),
                transform var(--dur-fast) var(--ease-expo),
                box-shadow var(--dur-fast) var(--ease-smooth);
    background: rgba(255, 255, 255, 0.015);
    cursor: default;
}

.showcase-card:hover {
    border-color: rgba(255, 255, 255, 0.2);
    transform: translateY(-6px);
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.4);
}

/* 卡片交错入场 */
.showcase-card {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity var(--dur-slower) var(--ease-expo),
                transform var(--dur-slower) var(--ease-expo),
                border-color var(--dur-fast) var(--ease-smooth),
                box-shadow var(--dur-fast) var(--ease-smooth);
}

.slide-content.visible .showcase-card {
    opacity: 1;
    transform: translateY(0);
}

.slide-content.visible .showcase-card:nth-child(1) { transition-delay: 0.35s; }
.slide-content.visible .showcase-card:nth-child(2) { transition-delay: 0.42s; }
.slide-content.visible .showcase-card:nth-child(3) { transition-delay: 0.49s; }
.slide-content.visible .showcase-card:nth-child(4) { transition-delay: 0.56s; }

.card-image {
    width: 100%;
    aspect-ratio: 4 / 3;
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.03) 0%, rgba(255, 255, 255, 0.005) 100%);
    transition: background var(--dur-slow) var(--ease-smooth);
}

.showcase-card:hover .card-image {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.05) 0%, rgba(255, 255, 255, 0.01) 100%);
}

.card-body {
    padding: 1.2rem;
    text-align: left;
}

.card-title {
    font-size: 0.9rem;
    font-weight: 400;
    color: var(--color-text-secondary);
    margin-bottom: 0.35rem;
    letter-spacing: 0.05em;
}

.card-author {
    font-size: 0.75rem;
    color: var(--color-text-muted);
    letter-spacing: 0.08em;
}

/* ==========================================
   Slide 4: 介绍 — 柔和光晕 (最后一页，无SCROLL)
   ========================================== */
.slide-about-detail {
    border-top: 1px solid rgba(255, 255, 255, 0.04);
}

.slide-about-detail::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 320px;
    height: 320px;
    border-radius: 50%;
    border: 1px solid rgba(255, 255, 255, 0.02);
    transform: translate(-50%, -50%);
    animation: rotateRing 35s linear infinite;
    pointer-events: none;
    z-index: 0;
}

.slide-about-detail::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 260px;
    height: 260px;
    border-radius: 50%;
    background: radial-gradient(circle,
        rgba(140, 150, 170, 0.05) 0%,
        rgba(100, 110, 140, 0.03) 30%,
        transparent 60%
    );
    transform: translate(-50%, -50%);
    animation: corePulse 7s ease-in-out infinite;
    pointer-events: none;
    z-index: 0;
}

/* Slide 4 (介绍) — 柔和蓝灰粒子 */
.slide-about-detail .particle-orbit::before {
    background: rgba(160, 170, 200, 0.25);
    box-shadow: 0 0 6px rgba(150, 160, 190, 0.35);
}

/* 关于页 - 引言高亮 */
.about-quote {
    font-size: 1.5rem;
    font-weight: 200;
    line-height: 1.8;
    color: var(--color-text-primary);
    letter-spacing: 0.12em;
    max-width: 560px;
    margin: 3rem auto 0;
    padding: 1.8rem 2.5rem;
    border-left: 2px solid rgba(255, 255, 255, 0.15);
    border-right: 2px solid rgba(255, 255, 255, 0.15);
    opacity: 0;
    transform: translateY(16px);
    transition: opacity var(--dur-slow) var(--ease-out) 0.35s,
                transform var(--dur-slow) var(--ease-out) 0.35s;
}

.slide-content.visible .about-quote {
    opacity: 1;
    transform: translateY(0);
}

/* 关于页 - 联系方式 */
.about-contact {
    margin-top: 2.5rem;
    opacity: 0;
    transform: translateY(10px);
    transition: opacity var(--dur-slow) var(--ease-out) 0.45s,
                transform var(--dur-slow) var(--ease-out) 0.45s;
}

.slide-content.visible .about-contact {
    opacity: 1;
    transform: translateY(0);
}

.about-contact a {
    color: var(--color-text-muted);
    text-decoration: none;
    font-size: 0.95rem;
    letter-spacing: 0.08em;
    transition: color var(--dur-normal) var(--ease-smooth);
}

.about-contact a:hover {
    color: var(--color-text-primary);
}

/* ==========================================
   页脚
   ========================================== */
.footer {
    position: relative;
    z-index: 1;
    text-align: center;
    padding: 2.5rem 2rem;
    color: var(--color-text-muted);
    font-size: 0.85rem;
    letter-spacing: 0.2em;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
    scroll-snap-align: start;
}

/* ==========================================
   响应式设计
   ========================================== */

/* 平板 ≤1024px */
@media (max-width: 1024px) {
    .black-hole {
        width: 500px;
        height: 500px;
    }

    .event-horizon {
        width: 150px;
        height: 150px;
    }

    .accretion-disk {
        width: 350px;
        height: 350px;
    }

    .disk-2 {
        width: 450px;
        height: 450px;
    }

    .disk-3 {
        width: 300px;
        height: 300px;
    }

    .brand-cn {
        font-size: 3rem;
    }

    .brand-en {
        font-size: 1.2rem;
        letter-spacing: 0.6em;
    }

    .slide-title {
        font-size: 2rem;
    }

    .showcase-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .nav-logo img {
        width: 120px;
    }
}

/* 移动端 ≤768px */
@media (max-width: 768px) {
    .nav-logo img {
        width: 100px;
    }

    .hamburger {
        display: flex;
    }

    .nav-container {
        padding: 1.2rem 1.5rem;
    }

    .nav-menu {
        position: fixed;
        top: 0;
        right: 0;
        height: 100vh;
        width: 260px;
        flex-direction: column;
        gap: 0;
        background: rgba(10, 10, 10, 0.98);
        backdrop-filter: blur(30px);
        -webkit-backdrop-filter: blur(30px);
        padding: 5rem 2rem 2rem;
        transform: translateX(100%);
        transition: transform var(--dur-normal) var(--ease-expo);
        z-index: 1000;
        border-left: 1px solid rgba(255, 255, 255, 0.05);
    }

    .nav-menu.active {
        transform: translateX(0);
    }

    .nav-menu > li {
        padding: 0.4rem 0;
        border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    }

    .nav-menu > li:last-child {
        border-bottom: none;
    }

    .nav-menu > li > a {
        font-size: 0.95rem;
        letter-spacing: 0.12em;
        display: block;
        padding: 0.2rem 0;
    }

    .dropdown-menu {
        position: static;
        left: auto;
        right: auto;
        transform: none;
        background: rgba(255, 255, 255, 0.03);
        border: none;
        border-left: 1px solid rgba(255, 255, 255, 0.15);
        border-radius: 0 6px 6px 0;
        box-shadow:
            0 0 12px rgba(255, 255, 255, 0.04),
            inset 0 1px 0 rgba(255, 255, 255, 0.04);
        padding: 0;
        margin-left: 0.5rem;
        margin-top: 0;
        opacity: 1;
        visibility: visible;
        min-width: auto;
        max-height: 0;
        overflow: hidden;
        transition: max-height var(--dur-normal) var(--ease-smooth),
                    padding var(--dur-normal) var(--ease-smooth),
                    margin var(--dur-normal) var(--ease-smooth);
    }

    .nav-dropdown.open .dropdown-menu {
        max-height: 100px;
        padding: 0.3rem 0 0.3rem 1rem;
        margin-top: 0.5rem;
    }

    .nav-dropdown:hover .dropdown-menu {
        transform: none;
    }

    .dropdown-menu a {
        padding: 0.4rem 0;
        font-size: 0.8rem;
    }

    .black-hole {
        width: 400px;
        height: 400px;
    }

    .event-horizon {
        width: 120px;
        height: 120px;
    }

    .accretion-disk {
        width: 280px;
        height: 280px;
    }

    .disk-2 {
        width: 350px;
        height: 350px;
    }

    .disk-3 {
        width: 240px;
        height: 240px;
    }

    .brand-cn {
        font-size: 2.4rem;
        letter-spacing: 0.3em;
    }

    .brand-en {
        font-size: 1rem;
        letter-spacing: 0.5em;
    }

    .brand-tagline {
        font-size: 0.95rem;
    }

    .brand {
        margin-bottom: 4rem;
    }

    .slide-title {
        font-size: 1.6rem;
    }

    .slide-desc {
        font-size: 0.9rem;
    }

    .about-quote {
        font-size: 1.1rem;
        padding: 1.2rem 1.5rem;
    }

    .slide-content {
        padding: 4rem 1.5rem;
    }

    .wechat-qr {
        flex-direction: column;
        align-items: center;
    }
}

/* 小屏手机 ≤480px */
@media (max-width: 480px) {
    .black-hole {
        width: 300px;
        height: 300px;
    }

    .event-horizon {
        width: 100px;
        height: 100px;
    }

    .accretion-disk {
        width: 220px;
        height: 220px;
    }

    .disk-2 {
        width: 280px;
        height: 280px;
    }

    .disk-3 {
        width: 180px;
        height: 180px;
    }

    .brand-cn {
        font-size: 1.9rem;
        letter-spacing: 0.25em;
    }

    .brand-en {
        font-size: 0.85rem;
        letter-spacing: 0.4em;
    }

    .brand-tagline {
        font-size: 0.85rem;
        padding: 0 1rem;
    }

    .nav-logo img {
        width: 80px;
    }

    .nav-menu {
        gap: 1.2rem;
    }

    .nav-menu > li > a {
        font-size: 0.7rem;
    }

    .slide-title {
        font-size: 1.35rem;
    }

    .slide-desc {
        font-size: 0.85rem;
    }

    .showcase-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }

    .qr-image {
        width: 130px;
        height: 130px;
    }

    .dropdown-menu {
        min-width: 140px;
    }

    .dropdown-menu a {
        font-size: 0.75rem;
        padding: 0.45rem 1rem;
    }
}