```css
/* ================================================
   YouTube下载官网 · Playful Editorial
   大胆排版 / 暖奶油底色 / 珊瑚×松石×琥珀
   ================================================ */

*, *::before, *::after {
    margin:0;
    padding:0;
    box-sizing:border-box;
}

html {
    scroll-behavior:smooth;
}

body {
    font-family: system-ui, -apple-system, 'PingFang SC', 'Microsoft YaHei', sans-serif;
    overflow-x:hidden;
    background:#FFFDF7;
    color:#2D3436;
    line-height:1.7;
    -webkit-font-smoothing:antialiased;
    text-rendering:optimizeLegibility;
}

::selection {
    background:#FFD93D;
    color:#2D3436;
}

::-webkit-scrollbar {
    width:10px;
}
::-webkit-scrollbar-track {
    background:#FFFDF7;
}
::-webkit-scrollbar-thumb {
    background:#FF6B6B;
    border-radius:10px;
    border:3px solid #FFFDF7;
}
::-webkit-scrollbar-thumb:hover {
    background:#2EC4B6;
}

/* ---------- 核心布局 ---------- */

.container {
    max-width:1200px;
    margin:0 auto;
    padding:0 24px;
}

.section {
    padding:100px 0;
    position:relative;
}

.section:nth-child(even) {
    background:#F7F4EE;
}

.section:nth-child(even)::after {
    content:'';
    position:absolute;
    bottom:0; left:50%;
    transform:translateX(-50%);
    width:80%;
    height:4px;
    background:repeating-linear-gradient(
        90deg,
        #FF6B6B 0 12px,
        #FFD93D 12px 24px,
        #2EC4B6 24px 36px
    );
    border-radius:4px;
    opacity:0.35;
}

/* ---------- 导航 ---------- */

.site-header {
    position:fixed;
    top:0; left:0;
    width:100%;
    z-index:1000;
    background:rgba(255,253,247,0.92);
    backdrop-filter:blur(16px);
    -webkit-backdrop-filter:blur(16px);
    border-bottom:2px solid #2D3436;
    box-shadow:0 4px 0 rgba(255,107,107,0.08);
}

.header-inner {
    display:flex;
    align-items:center;
    justify-content:space-between;
    height:72px;
    max-width:1200px;
    margin:0 auto;
    padding:0 24px;
}

.logo {
    display:flex;
    align-items:center;
    gap:10px;
    font-weight:800;
    font-size:1.25rem;
    text-decoration:none;
    color:#2D3436;
    letter-spacing:-0.5px;
}

.logo-icon {
    width:40px; height:40px;
    border-radius:12px;
    background:#FF6B6B;
    display:flex;
    align-items:center;
    justify-content:center;
    font-size:1rem;
    position:relative;
    box-shadow:0 3px 0 rgba(45,52,54,0.25);
    transition:transform .25s cubic-bezier(.34,1.56,.64,1);
}

.logo:hover .logo-icon {
    transform:rotate(-8deg) scale(1.06);
}

.logo-icon::after {
    content:'';
    border-left:9px solid #fff;
    border-top:6px solid transparent;
    border-bottom:6px solid transparent;
    margin-left:3px;
    filter:drop-shadow(1px 1px 0 rgba(0,0,0,0.1));
}

.main-nav {
    display:flex;
    align-items:center;
    gap:28px;
    list-style:none;
}

.main-nav a {
    text-decoration:none;
    font-size:0.92rem;
    font-weight:600;
    color:#2D3436;
    position:relative;
    padding:4px 2px;
    transition:color .2s;
}

.main-nav a:not(.nav-cta)::after {
    content:'';
    position:absolute;
    bottom:-3px; left:0;
    width:0; height:3px;
    background:#FFD93D;
    border-radius:2px;
    transition:width .3s cubic-bezier(.68,-.55,.27,1.55);
}

.main-nav a:not(.nav-cta):hover {
    color:#FF6B6B;
}

.main-nav a:not(.nav-cta):hover::after {
    width:100%;
}

.nav-cta {
    padding:10px 24px;
    border-radius:50px;
    background:#FF6B6B;
    color:#fff !important;
    font-weight:700;
    box-shadow:0 4px 0 rgba(45,52,54,0.2);
    transition:transform .2s, box-shadow .2s;
}

.nav-cta:hover {
    transform:translateY(-2px);
    box-shadow:0 6px 0 rgba(45,52,54,0.2);
    color:#fff !important;
}

.menu-toggle {
    display:none;
    width:42px; height:42px;
    border-radius:10px;
    background:#FFD93D;
    border:2px solid #2D3436;
    cursor:pointer;
    align-items:center;
    justify-content:center;
    font-size:1.1rem;
    color:#2D3436;
    box-shadow:0 3px 0 rgba(45,52,54,0.15);
    transition:transform .2s;
}

.menu-toggle:hover {
    transform:scale(1.05);
}

/* ---------- Hero ---------- */

.hero {
    min-height:80vh;
    display:flex;
    align-items:center;
    gap:56px;
    padding-top:72px;
    position:relative;
    overflow:hidden;
    background-image:
        radial-gradient(rgba(45,52,54,0.07) 1px, transparent 1px);
    background-size:28px 28px;
}

.hero::before {
    content:'';
    position:absolute;
    width:360px; height:360px;
    border-radius:50%;
    background:#2EC4B6;
    opacity:0.12;
    top:-100px; right:-80px;
    pointer-events:none;
}

.hero::after {
    content:'';
    position:absolute;
    width:200px; height:200px;
    border-radius:50%;
    background:#FFD93D;
    opacity:0.25;
    bottom:20px; left:-50px;
    pointer-events:none;
}

.hero-content {
    flex:1 1 60%;
    max-width:620px;
    position:relative;
    z-index:2;
}

.hero-eyebrow {
    display:inline-block;
    font-size:0.85rem;
    font-weight:800;
    padding:7px 18px;
    border-radius:50px;
    background:#2EC4B6;
    color:#fff;
    margin-bottom:20px;
    letter-spacing:0.5px;
    box-shadow:0 3px 0 rgba(45,52,54,0.25);
    transform:rotate(-1deg);
    text-transform:uppercase;
}

.hero h1 {
    font-size:clamp(2.6rem, 5vw, 3.6rem);
    line-height:1.1;
    margin-bottom:24px;
    font-weight:800;
    letter-spacing:-2px;
    color:#2D3436;
    position:relative;
    display:inline-block;
}

.hero h1::after {
    content:'';
    position:absolute;
    bottom:4px; left:-2px;
    width:calc(100% + 4px);
    height:36%;
    background:linear-gradient(90deg, rgba(255,217,61,0.5), rgba(255,107,107,0.35));
    z-index:-1;
    border-radius:4px;
    transform:rotate(-0.6deg);
}

.hero p {
    font-size:1.1rem;
    color:#5D5A52;
    max-width:540px;
    margin-bottom:36px;
}

.hero-buttons {
    display:flex;
    gap:16px;
    flex-wrap:wrap;
}

.hero-image {
    flex:1 1 340px;
    max-width:440px;
    position:relative;
    border-radius:20px;
    overflow:hidden;
    border:3px solid #2D3436;
    box-shadow:12px 12px 0 #2EC4B6;
    transform:rotate(1.5deg);
    transition:transform .35s cubic-bezier(.34,1.56,.64,1);
    min-height:280px;
    background:linear-gradient(135deg, #F0EDE6 0%, #E4DFD3 100%);
}

.hero-image:hover {
    transform:rotate(0deg) scale(1.02);
    box-shadow:16px 16px 0 rgba(46,196,182,0.35);
}

.hero-image img {
    width:100%;
    height:auto;
    display:block;
}

.hero-image::before {
    content:'';
    position:absolute;
    top:50%; left:50%;
    transform:translate(-50%,-50%);
    width:76px; height:76px;
    background:#FF6B6B;
    border-radius:50%;
    border:4px solid #fff;
    z-index:2;
    box-shadow:0 4px 0 rgba(45,52,54,0.2), 0 8px 24px rgba(255,107,107,0.4);
}

.hero-image::after {
    content:'';
    position:absolute;
    top:50%; left:50%;
    transform:translate(-32%,-50%);
    border-left:22px solid #fff;
    border-top:14px solid transparent;
    border-bottom:14px solid transparent;
    z-index:3;
    filter:drop-shadow(0 2px 0 rgba(0,0,0,0.1));
}

/* ---------- 按钮 ---------- */

.btn {
    display:inline-flex;
    align-items:center;
    gap:8px;
    padding:14px 32px;
    border-radius:50px;
    font-weight:700;
    cursor:pointer;
    border:none;
    text-decoration:none;
    font-size:0.95rem;
    transition:transform .2s, box-shadow .2s, background .2s;
}

.btn-primary {
    background:#FF6B6B;
    color:#fff;
    box-shadow:0 4px 0 rgba(45,52,54,0.2);
}

.btn-primary:hover {
    transform:translateY(-3px);
    box-shadow:0 7px 0 rgba(45,52,54,0.2);
}

.btn-primary:active {
    transform:translateY(0);
    box-shadow:0 3px 0 rgba(45,52,54,0.2);
}

.btn-outline {
    background:transparent;
    border:1.5px solid #2D3436;
    color:#2D3436;
    box-shadow:0 4px 0 rgba(45,52,54,0.1);
}

.btn-outline:hover {
    background:#2D3436;
    color:#fff;
    transform:translateY(-3px);
    box-shadow:0 7px 0 rgba(45,52,54,0.2);
}

.btn-outline:active {
    transform:translateY(0);
}

/* ---------- 标签 / 标题 ---------- */

.section-label {
    display:inline-block;
    font-size:0.8rem;
    font-weight:800;
    letter-spacing:2.5px;
    text-transform:uppercase;
    margin-bottom:14px;
    color:#2D3436;
    background:#fff;
    padding:5px 14px;
    border-radius:6px;
    border:2px solid #2D3436;
    box-shadow:3px 3px 0 #2D3436;
    transform:rotate(-2deg);
}

.section-title {
    font-size:2.4rem;
    margin-bottom:14px;
    font-weight:800;
    letter-spacing:-1px;
    line-height:1.2;
    position:relative;
}

.section-desc {
    max-width:600px;
    color:#6B6A63;
    margin-bottom:44px;
    font-size:1.05rem;
}

/* ---------- 卡片网格 ---------- */

.cards-grid {
    display:grid;
    grid-template-columns:repeat(auto-fill,minmax(260px,1fr));
    gap:28px;
}

.category-card {
    background:#fff;
    border-radius:16px;
    padding:30px 28px;
    border:2px solid #2D3436;
    transition:transform .3s cubic-bezier(.34,1.56,.64,1), box-shadow .3s;
    position:relative;
    overflow:hidden;
}

.category-card::before {
    content:'';
    position:absolute;
    top:0; left:0;
    width:100%; height:6px;
    background:var(--card-accent, #FF6B6B);
}

.category-card:nth-child(3n+1) { --card-accent:#FF6B6B; }
.category-card:nth-child(3n+2) { --card-accent:#2EC4B6; }
.category-card:nth-child(3n+3) { --card-accent:#FFD93D; }

.category-card:hover {
    transform:translateY(-8px) rotate(-0.8deg);
    box-shadow:10px 10px 0 rgba(45,52,54,0.12);
}

.card-icon {
    width:54px; height:54px;
    border-radius:14px;
    display:flex;
    align-items:center;
    justify-content:center;
    margin-bottom:16px;
    font-size:1.4rem;
    background:#FFF;
    border:2px solid #2D3436;
    box-shadow:4px 4px 0 rgba(45,52,54,0.1);
    transition:transform .3s cubic-bezier(.34,1.56,.64,1);
}

.category-card:hover .card-icon {
    transform:scale(1.12) rotate(-10deg);
}

.card-link {
    font-weight:700;
    font-size:0.85rem;
    text-decoration:none;
    color:#FF6B6B;
    display:inline-flex;
    align-items:center;
    gap:4px;
    transition:color .2s;
}

.card-link::after {
    content:'→';
    transition:transform .25s;
}

.card-link:hover {
    color:#2EC4B6;
}

.card-link:hover::after {
    transform:translateX(5px);
}

/* ---------- 特性块 ---------- */

.feature-block {
    display:grid;
    grid-template-columns:1fr 1fr;
    gap:64px;
    align-items:center;
}

.feature-image {
    border-radius:20px;
    overflow:hidden;
    border:2px solid #2D3436;
    box-shadow:12px 12px 0 #FFD93D;
    transform:rotate(-1.5deg);
    transition:transform .35s, box-shadow .35s;
}

.feature-image:hover {
    transform:rotate(0deg) scale(1.02);
    box-shadow:12px 12px 0 rgba(255,217,61,0.6);
}

.feature-image img {
    width:100%;
    height:auto;
    display:block;
}

.feature-text h3 {
    font-size:1.4rem;
    font-weight:800;
    margin-bottom:14px;
    letter-spacing:-0.5px;
}

.feature-text p {
    color:#6B6A63;
    margin-bottom:16px;
}

.feature-list {
    list-style:none;
    margin-top:8px;
}

.feature-list li {
    padding:10px 0;
    display:flex;
    align-items:center;
    gap:12px;
    border-bottom:2px dashed rgba(45,52,54,0.12);
    font-weight:500;
}

.feature-list li:last-child {
    border-bottom:none;
}

.feature-list li::before {
    content:'✓';
    font-weight:800;
    width:28px; height:28px;
    border-radius:50%;
    background:#2EC4B6;
    color:#fff;
    display:flex;
    align-items:center;
    justify-content:center;
    font-size:0.8rem;
    flex-shrink:0;
    box-shadow:0 2px 0 rgba(45,52,54,0.2);
}

/* ---------- 数据条 ---------- */

.stats-bar {
    display:grid;
    grid-template-columns:repeat(4,1fr);
    gap:28px;
    text-align:center;
}

.stat-item {
    padding:32px 16px;
    border-radius:16px;
    background:#fff;
    border:2px solid #2D3436;
    box-shadow:6px 6px 0 rgba(45,52,54,0.12);
    transition:transform .3s cubic-bezier(.34,1.56,.64,1), box-shadow .3s;
    position:relative;
    overflow:hidden;
}

.stat-item::after {
    content:'';
    position:absolute;
    bottom:-30px; right:-30px;
    width:80px; height:80px;
    border-radius:50%;
    background:var(--stat-color, #FF6B6B);
    opacity:0.08;
    transition:transform .3s, opacity .3s;
}

.stat-item:hover {
    transform:translateY(-6px);
    box-shadow:10px 10px 0 rgba(45,52,54,0.1);
}

.stat-item:hover::after {
    transform:scale(1.4);
    opacity:0.15;
}

.stat-item:nth-child(1) { --stat-color:#FF6B6B; }
.stat-item:nth-child(2) { --stat-color:#2EC4B6; }
.stat-item:nth-child(3) { --stat-color:#FFD93D; }
.stat-item:nth-child(4) { --stat-color:#A29BFE; }

.stat-number {
    font-size:2.6rem;
    font-weight:800;
    line-height:1.1;
    color:#2D3436;
    letter-spacing:-1px;
}

.stat-item:nth-child(1) .stat-number { color:#FF6B6B; }
.stat-item:nth-child(2) .stat-number { color:#2EC4B6; }
.stat-item:nth-child(3) .stat-number { color:#D4A700; }
.stat-item:nth-child(4) .stat-number { color:#8B7CF6; }

.stat-label {
    font-size:0.9rem;
    color:#6B6A63;
    margin-top:6px;
    font-weight:500;
}

/* ---------- 内容墙 ---------- */

.content-wall {
    display:grid;
    grid-template-columns:repeat(auto-fill,minmax(280px,1fr));
    gap:28px;
}

.content-wall-item {
    border-radius:16px;
    overflow:hidden;
    background:#fff;
    border:2px solid #2D3436;
    transition:transform .3s cubic-bezier(.34,1.56,.64,1), box-shadow .3s;
}

.content-wall-item:hover {
    transform:translateY(-8px) rotate(1deg);
    box-shadow:10px 10px 0 rgba(46,196,182,0.25);
}

.content-wall-item img {
    width:100%;
    height:200px;
    object-fit:cover;
    border-bottom:2px solid #2D3436;
    transition:transform .4s;
}

.content-wall-item:hover img {
    transform:scale(1.05);
}

.content-wall-body {
    padding:22px;
}

.content-wall-body h4 {
    font-size:1.05rem;
    font-weight:700;
    margin-bottom:6px;
}

.content-wall-body p {
    font-size:0.9rem;
    color:#6B6A63;
}

/* ---------- FAQ ---------- */

.faq-list {
    max-width:800px;
    margin:0 auto;
}

.faq-item {
    background:#fff;
    border:2px solid #2D3436;
    border-radius:14px;
    margin-bottom:14px;
    overflow:hidden;
    cursor:pointer;
    transition:box-shadow .25s, border-color .25s;
}

.faq-item:hover {
    box-shadow:6px 6px 0 rgba(45,52,54,0.1);
}

.faq-item.open {
    border-color:#FF6B6B;
    box-shadow:6px 6px 0 rgba(255,107,107,0.2);
}

.faq-item .faq-question {
    padding:18px 22px;
    font-weight:700;
    display:flex;
    justify-content:space-between;
    align-items:center;
    font-size:1rem;
    letter-spacing:-0.3px;
}

.faq-item .faq-question::after {
    content:'+';
    font-size:1.4rem;
    font-weight:800;
    color:#FF6B6B;
    transition:transform .3s cubic-bezier(.34,1.56,.64,1);
    flex-shrink:0;
    margin-left:16px;
}

.faq-item.open .faq-question::after {
    content:'−';
    transform:rotate(180deg);
}

.faq-item .faq-answer {
    padding:0 22px 18px;
    display:none;
    color:#5D5A52;
    font-size:0.95rem;
}

.faq-item.open .faq-answer {
    display:block;
    animation:faqFade .3s ease;
}

@keyframes faqFade {
    from { opacity:0; transform:translateY(-6px); }
    to   { opacity:1; transform:translateY(0); }
}

/* ---------- CTA 横幅 ---------- */

.cta-banner {
    padding:68px 24px;
    text-align:center;
    border-radius:24px;
    position:relative;
    overflow:hidden;
    background:linear-gradient(135deg, #FF6B6B 0%, #FF8E53 55%, #FFB347 100%);
    border:3px solid #2D3436;
    box-shadow:0 8px 0 rgba(45,52,54,0.15);
    color:#fff;
}

.cta-banner::before {
    content:'';
    position:absolute;
    width:220px; height:220px;
    border-radius:50%;
    background:rgba(255,255,255,0.12);
    top:-80px; right:-60px;
}

.cta-banner::after {
    content:'';
    position:absolute;
    width:160px; height:160px;
    border-radius:50%;
    background:rgba(255,255,255,0.1);
    bottom:-70px; left:-40px;
}

.cta-banner h2 {
    font-size:2.3rem;
    color:#fff;
    margin-bottom:12px;
    font-weight:800;
    letter-spacing:-1px;
    text-shadow:0 2px 8px rgba(0,0,0,0.15);
    position:relative;
    z-index:2;
}

.cta-banner p {
    color:rgba(255,255,255,0.92);
    margin-bottom:28px;
    font-size:1.05rem;
    max-width:480px;
    margin-left:auto;
    margin-right:auto;
    position:relative;
    z-index:2;
}

.cta-banner .btn-primary {
    background:#fff;
    color:#FF6B6B;
    box-shadow:0 4px 0 rgba(0,0,0,0.2);
    position:relative;
    z-index:2;
}

.cta-banner .btn-primary:hover {
    transform:translateY(-3px);
    box-shadow:0 7px 0 rgba(0,0,0,0.2);
}

/* ---------- 页脚 ---------- */

.site-footer {
    padding:60px 0 28px;
    background:#2EC4B6;
    border-top:4px solid #2D3436;
    color:#2D3436;
    position:relative;
}

.site-footer::before {
    content:'';
    position:absolute;
    top:-14px; left:0;
    width:100%; height:14px;
    background:repeating-linear-gradient(
        90deg,
        #FF6B6B 0 18px,
        #FFD93D 18px 36px,
        #FF6B6B 36px 54px
    );
    opacity:0.6;
}

.footer-grid {
    display:grid;
    grid-template-columns:2fr 1fr 1fr 1fr;
    gap:48px;
}

.footer-brand h3 {
    font-size:1.3rem;
    font-weight:800;
    margin-bottom:10px;
    letter-spacing:-0.5px;
}

.footer-brand p {
    opacity:0.75;
    font-size:0.92rem;
    max-width:280px;
}

.footer-col h4 {
    font-size:0.85rem;
    font-weight:800;
    margin-bottom:16px;
    letter-spacing:1.5px;
    text-transform:uppercase;
    opacity:0.8;
}

.footer-col a {
    display:block;
    color:#2D3436;
    text-decoration:none;
    padding:5px 0;
    font-size:0.9rem;
    opacity:0.75;
    transition:opacity .2s, transform .2s;
}

.footer-col a:hover {
    opacity:1;
    transform:translateX(4px);
}

.footer-bottom {
    border-top:1px solid rgba(45,52,54,0.2);
    margin-top:48px;
    padding-top:22px;
    text-align:center;
    font-size:0.85rem;
    opacity:0.7;
}

/* ---------- 工具类 ---------- */

.text-accent {
    color:#FF6B6B;
    font-weight:700;
}

.text-center {
    text-align:center;
}

.seo-description {
    max-width:600px;
    margin:0 auto 48px;
    color:#6B6A63;
    text-align:center;
    line-height:1.8;
}

.mt-0 {
    margin-top:0;
}

.mb-0 {
    margin-bottom:0;
}

/* ---------- 动画 ---------- */

@keyframes floatSoft {
    0%, 100% { transform:translateY(0) rotate(0deg); }
    50%      { transform:translateY(-12px) rotate(1deg); }
}

.hero-eyebrow {
    animation:floatSoft 4s ease-in-out infinite;
}

/* ---------- 响应式 ---------- */

@media (max-width: 992px) {
    .hero {
        gap:32px;
        flex-wrap:wrap;
    }
    .hero-content {
        flex:1 1 100%;
        max-width:100%;
    }
    .hero-image {
        flex:1 1 100%;
        max-width:420px;
        margin:0 auto;
    }
    .feature-block {
        gap:40px;
    }
}

@media (max-width: 768px) {
    .section {
        padding:70px 0;
    }

    .feature-block {
        grid-template-columns:1fr;
    }

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

    .footer-grid {
        grid-template-columns:1fr 1fr;
        gap:36px;
    }

    .main-nav {
        display:none;
    }

    .menu-toggle {
        display:flex;
    }

    .main-nav.open {
        display:flex;
        flex-direction:column;
        position:absolute;
        top:72px; left:0;
        width:100%;
        background:#FFFDF7;
        padding:24px;
        gap:18px;
        border-bottom:2px solid #2D3436;
        box-shadow:0 8px 24px rgba(45,52,54,0.08);
    }

    .main-nav.open .nav-cta {
        text-align:center;
        padding:12px 24px;
    }

    .hero {
        padding-top:100px;
        min-height:auto;
        padding-bottom:60px;
        flex-direction:column;
    }

    .hero-image {
        max-width:100%;
        width:100%;
    }

    .hero h1 {
        font-size:2.4rem;
    }

    .section-title {
        font-size:1.9rem;
    }

    .cta-banner h2 {
        font-size:1.8rem;
    }

    .hero-buttons {
        flex-wrap:wrap;
    }
}

@media (max-width: 480px) {
    .cards-grid,
    .content-wall,
    .stats-bar {
        grid-template-columns:1fr;
    }

    .footer-grid {
        grid-template-columns:1fr;
    }

    .hero-buttons {
        flex-direction:column;
        width:100%;
    }

    .hero-buttons .btn {
        width:100%;
        justify-content:center;
    }

    .hero h1 {
        font-size:2rem;
    }

    .hero p {
        font-size:1rem;
    }

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

    .stat-item {
        padding:24px 12px;
    }

    .stat-number {
        font-size:2.2rem;
    }

    .cta-banner {
        padding:48px 16px;
    }

    .cta-banner h2 {
        font-size:1.5rem;
    }

    .footer-grid {
        gap:28px;
    }

    .btn-primary,
    .btn-outline {
        padding:12px 24px;
        font-size:0.9rem;
    }
}

/* ---------- 打印优化 ---------- */

@media print {
    .site-header,
    .nav-cta,
    .menu-toggle,
    .hero-buttons,
    .cta-banner {
        display:none !important;
    }

    body {
        background:#fff;
        color:#000;
    }

    .section {
        padding:32px 0;
    }
}