/* ===== 全局重置 & 变量 ===== */
:root {
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #a5b4fc;
    --secondary: #06b6d4;
    --accent: #8b5cf6;
    --gradient: linear-gradient(135deg, #6366f1, #8b5cf6, #06b6d4);
    --gradient-text: linear-gradient(135deg, #a5b4fc, #06b6d4);
    --bg-body: #0f172a;
    --bg-card: #1e293b;
    --bg-card-hover: #273548;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --border-color: #334155;
    --shadow-sm: 0 2px 8px rgba(0,0,0,0.3);
    --shadow-lg: 0 10px 40px rgba(0,0,0,0.4);
    --radius-sm: 8px;
    --radius-md: 16px;
    --radius-lg: 24px;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --max-width: 1200px;
    --header-height: 72px;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--bg-body);
    color: var(--text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

a {
    color: var(--primary-light);
    text-decoration: none;
    transition: var(--transition);
}

a:hover {
    color: var(--secondary);
}

img {
    max-width: 100%;
    display: block;
}

ul {
    list-style: none;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* ===== 导航栏 ===== */
header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    background: rgba(15, 23, 42, 0.8);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid transparent;
    transition: background 0.3s, border-color 0.3s, box-shadow 0.3s;
    height: var(--header-height);
}

header.scrolled {
    background: rgba(15, 23, 42, 0.95);
    border-bottom: 1px solid var(--border-color);
    box-shadow: 0 4px 20px rgba(0,0,0,0.3);
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: var(--header-height);
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo i {
    background: var(--gradient);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    font-size: 1.8rem;
}

.nav-menu ul {
    display: flex;
    gap: 32px;
}

.nav-menu a {
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.95rem;
    padding: 6px 0;
    position: relative;
}

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--gradient);
    transition: var(--transition);
    border-radius: 2px;
}

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

.nav-menu a:hover::after,
.nav-menu a.active::after {
    width: 100%;
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 12px;
}

.btn-download-nav {
    background: var(--gradient);
    color: #fff !important;
    padding: 8px 20px;
    border-radius: 50px;
    font-weight: 600;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: var(--transition);
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.3);
}

.btn-download-nav:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(99, 102, 241, 0.4);
}

.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.hamburger span {
    width: 26px;
    height: 2.5px;
    background: var(--text-primary);
    border-radius: 4px;
    transition: var(--transition);
}

.hamburger.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

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

.hamburger.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
}

/* ===== Hero 区域 ===== */
.hero-section {
    padding: calc(var(--header-height) + 40px) 0 80px;
    position: relative;
    overflow: hidden;
    min-height: 100vh;
    display: flex;
    align-items: center;
}

.hero-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.hero-content .badge {
    display: inline-block;
    background: rgba(99, 102, 241, 0.2);
    border: 1px solid rgba(99, 102, 241, 0.3);
    color: var(--primary-light);
    padding: 6px 16px;
    border-radius: 50px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 20px;
    backdrop-filter: blur(4px);
}

.hero-content h1 {
    font-size: 3.5rem;
    font-weight: 800;
    line-height: 1.15;
    margin-bottom: 20px;
}

.gradient-text {
    background: var(--gradient-text);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-content p {
    font-size: 1.15rem;
    color: var(--text-secondary);
    max-width: 520px;
    margin-bottom: 32px;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
    margin-bottom: 40px;
}

.btn-primary,
.btn-secondary {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    padding: 14px 32px;
    border-radius: 50px;
    font-weight: 600;
    font-size: 1rem;
    transition: var(--transition);
    cursor: pointer;
    border: none;
}

.btn-primary {
    background: var(--gradient);
    color: #fff;
    box-shadow: 0 4px 20px rgba(99, 102, 241, 0.35);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 30px rgba(99, 102, 241, 0.45);
}

.btn-secondary {
    background: rgba(255,255,255,0.08);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    backdrop-filter: blur(4px);
}

.btn-secondary:hover {
    background: rgba(255,255,255,0.15);
    transform: translateY(-3px);
    border-color: var(--primary-light);
}

.hero-stats {
    display: flex;
    gap: 40px;
}

.stat-item {
    display: flex;
    flex-direction: column;
}

.stat-number {
    font-size: 1.8rem;
    font-weight: 800;
    background: var(--gradient);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.stat-label {
    font-size: 0.85rem;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    gap: 4px;
    margin-top: 2px;
}

.stat-label i {
    color: #fbbf24;
    font-size: 0.75rem;
}

/* ===== 手机模拟 ===== */
.hero-visual {
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
}

.phone-mockup {
    width: 280px;
    height: 560px;
    background: linear-gradient(145deg, #1e293b, #0f172a);
    border-radius: 40px;
    padding: 12px;
    box-shadow: 0 20px 60px rgba(0,0,0,0.6), inset 0 1px 0 rgba(255,255,255,0.1);
    border: 1px solid var(--border-color);
    position: relative;
}

.phone-screen {
    width: 100%;
    height: 100%;
    background: #0f172a;
    border-radius: 30px;
    overflow: hidden;
    padding: 16px;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
}

.chat-demo {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.chat-message {
    max-width: 85%;
    padding: 12px 16px;
    border-radius: 18px;
    font-size: 0.85rem;
    line-height: 1.4;
    animation: fadeInUp 0.5s ease;
}

.chat-message.bot {
    background: var(--bg-card);
    color: var(--text-primary);
    align-self: flex-start;
    border-bottom-left-radius: 4px;
}

.chat-message.user {
    background: var(--primary);
    color: #fff;
    align-self: flex-end;
    border-bottom-right-radius: 4px;
}

.chat-message.typing {
    background: var(--bg-card);
    align-self: flex-start;
    display: flex;
    gap: 6px;
    padding: 14px 18px;
    border-bottom-left-radius: 4px;
}

.chat-message.typing span {
    width: 8px;
    height: 8px;
    background: var(--text-muted);
    border-radius: 50%;
    animation: typingBounce 1.4s infinite;
}

.chat-message.typing span:nth-child(2) { animation-delay: 0.2s; }
.chat-message.typing span:nth-child(3) { animation-delay: 0.4s; }

.float-shape {
    position: absolute;
    border-radius: 50%;
    filter: blur(60px);
    opacity: 0.3;
    z-index: -1;
}

.float-shape.shape-1 {
    width: 300px;
    height: 300px;
    background: #6366f1;
    top: -80px;
    right: -80px;
}

.float-shape.shape-2 {
    width: 200px;
    height: 200px;
    background: #06b6d4;
    bottom: -40px;
    left: -60px;
}

/* 波形分隔 */
.hero-wave {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    line-height: 0;
}

.hero-wave svg {
    display: block;
    width: 100%;
    height: 120px;
}

/* ===== 通用 section 头部 ===== */
.section-header {
    text-align: center;
    margin-bottom: 56px;
}

.section-header h2 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 12px;
}

.section-header p {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* ===== 功能特色 ===== */
.features-section {
    padding: 80px 0;
    background: var(--bg-body);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.feature-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 32px 24px;
    transition: var(--transition);
    cursor: default;
}

.feature-card:hover {
    background: var(--bg-card-hover);
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
}

.feature-icon {
    width: 56px;
    height: 56px;
    background: rgba(99, 102, 241, 0.15);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.6rem;
    color: var(--primary-light);
    margin-bottom: 20px;
    transition: var(--transition);
}

.feature-card:hover .feature-icon {
    background: rgba(99, 102, 241, 0.25);
    transform: scale(1.05);
}

.feature-card h3 {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 10px;
}

.feature-card p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.6;
}

/* ===== 下载平台 ===== */
.platforms-section {
    padding: 80px 0;
    background: var(--bg-card);
}

.platform-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
    margin-bottom: 40px;
}

.platform-card {
    background: var(--bg-body);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 32px 20px;
    text-align: center;
    transition: var(--transition);
}

.platform-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
}

.platform-icon {
    font-size: 3rem;
    color: var(--primary-light);
    margin-bottom: 16px;
}

.platform-card h3 {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: 6px;
}

.platform-card p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 12px;
}

.platform-version {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-bottom: 20px;
    padding: 4px 12px;
    background: rgba(99, 102, 241, 0.1);
    display: inline-block;
    border-radius: 50px;
}

.btn-download {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: var(--gradient);
    color: #fff;
    padding: 12px 24px;
    border-radius: 50px;
    font-weight: 600;
    font-size: 0.9rem;
    transition: var(--transition);
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.2);
}

.btn-download:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(99, 102, 241, 0.35);
    color: #fff;
}

.download-note {
    text-align: center;
    color: var(--text-muted);
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    flex-wrap: wrap;
}

.download-note i {
    color: var(--primary-light);
}

.download-note a {
    color: var(--primary-light);
    text-decoration: underline;
}

/* ===== FAQ ===== */
.faq-section {
    padding: 80px 0;
    background: var(--bg-body);
}

.faq-list {
    max-width: 720px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.faq-item {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    overflow: hidden;
    transition: var(--transition);
}

.faq-item:hover {
    border-color: var(--primary);
}

.faq-question {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 24px;
    font-weight: 500;
    cursor: pointer;
    user-select: none;
    transition: var(--transition);
}

.faq-question i {
    transition: var(--transition);
    color: var(--text-muted);
    font-size: 0.9rem;
}

.faq-item.active .faq-question i {
    transform: rotate(180deg);
    color: var(--primary-light);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease, padding 0.4s ease;
}

.faq-item.active .faq-answer {
    max-height: 300px;
    padding: 0 24px 20px;
}

.faq-answer p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.7;
}

/* ===== 页脚 ===== */
.footer {
    background: #0a0f1a;
    padding: 60px 0 0;
    border-top: 1px solid var(--border-color);
}

.footer-grid {
    display: grid;
    grid-template-columns: 1.5fr 2fr;
    gap: 60px;
    padding-bottom: 40px;
}

.footer-brand .logo {
    margin-bottom: 16px;
    font-size: 1.4rem;
}

.footer-brand p {
    color: var(--text-muted);
    font-size: 0.95rem;
    margin-bottom: 20px;
}

.footer-social {
    display: flex;
    gap: 16px;
}

.footer-social a {
    width: 40px;
    height: 40px;
    background: var(--bg-card);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-secondary);
    font-size: 1.1rem;
    transition: var(--transition);
}

.footer-social a:hover {
    background: var(--primary);
    color: #fff;
    transform: translateY(-3px);
}

.footer-links {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.footer-col h4 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--text-primary);
}

.footer-col ul li {
    margin-bottom: 10px;
}

.footer-col ul li a {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.footer-col ul li a:hover {
    color: var(--primary-light);
}

.footer-bottom {
    border-top: 1px solid var(--border-color);
    padding: 20px 0;
    text-align: center;
    color: var(--text-muted);
    font-size: 0.85rem;
}

/* ===== 响应式 ===== */
@media (max-width: 1024px) {
    .hero-grid {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero-content p {
        margin: 0 auto 32px;
    }

    .hero-buttons {
        justify-content: center;
    }

    .hero-stats {
        justify-content: center;
    }

    .hero-visual {
        order: -1;
        margin-bottom: 20px;
    }

    .phone-mockup {
        width: 220px;
        height: 440px;
    }

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

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

@media (max-width: 768px) {
    :root {
        --header-height: 64px;
    }

    .nav-menu {
        position: fixed;
        top: var(--header-height);
        left: 0;
        width: 100%;
        background: rgba(15, 23, 42, 0.98);
        backdrop-filter: blur(20px);
        padding: 20px 24px;
        transform: translateY(-120%);
        opacity: 0;
        transition: var(--transition);
        border-bottom: 1px solid var(--border-color);
        box-shadow: var(--shadow-lg);
    }

    .nav-menu.open {
        transform: translateY(0);
        opacity: 1;
    }

    .nav-menu ul {
        flex-direction: column;
        gap: 20px;
    }

    .nav-menu a {
        font-size: 1.1rem;
    }

    .hamburger {
        display: flex;
    }

    .btn-download-nav {
        display: none;
    }

    .hero-content h1 {
        font-size: 2.2rem;
    }

    .hero-stats {
        gap: 24px;
        flex-wrap: wrap;
    }

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

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

    .footer-grid {
        grid-template-columns: 1fr;
        gap: 40px;
    }

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

    .section-header h2 {
        font-size: 2rem;
    }

    .phone-mockup {
        width: 180px;
        height: 360px;
    }

    .hero-wave svg {
        height: 60px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 16px;
    }

    .hero-content h1 {
        font-size: 1.8rem;
    }

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

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

/* ===== 动画 ===== */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes typingBounce {
    0%, 60%, 100% {
        transform: translateY(0);
        opacity: 0.4;
    }
    30% {
        transform: translateY(-8px);
        opacity: 1;
    }
}