/* CSS Variables for Parchment Theme */
:root {
    --bg-parchment: #f9f5eb;        /* Light parchment background */
    --bg-parchment-dark: #eee7d5;   /* Slightly darker parchment for sections */
    --text-main: #3a332a;           /* Dark brown for text, easy on eyes */
    --text-muted: #6b6255;          /* Muted brown for descriptions */
    --accent-primary: #3b5a4a;      /* Vintage dark green for primary actions */
    --accent-hover: #2c4437;        /* Darker green for hover */
    --accent-secondary: #8c4a3b;    /* Vintage rust red for secondary/highlights */
    --border-color: #d1c7b3;        /* Warm border color */
    --font-sans: 'Noto Sans SC', sans-serif;
    --font-serif: 'Noto Serif SC', serif;
    --transition: all 0.3s ease;
}

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

body {
    font-family: var(--font-sans);
    background-color: var(--bg-parchment);
    color: var(--text-main);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

a {
    text-decoration: none;
    color: inherit;
}

ul {
    list-style: none;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header & Navigation */
.header {
    background-color: rgba(249, 245, 235, 0.95);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(5px);
}

.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

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

.nav__logo i {
    color: var(--accent-secondary);
}

.nav__logo-img {
    width: 30px;
    height: 30px;
    object-fit: contain;
    display: block;
}

.nav__links {
    display: flex;
    gap: 30px;
    align-items: center;
}

.nav__link {
    font-weight: 500;
    transition: var(--transition);
}

.nav__link:hover {
    color: var(--accent-secondary);
}

.nav__link--active {
    color: var(--accent-primary);
    font-weight: 700;
    border-bottom: 2px solid var(--accent-primary);
    padding-bottom: 2px;
}

/* ── 桌面语言下拉 ── */
.nav-lang-mobile { display: none; }   /* 默认隐藏移动版 */

.lang-switch {
    position: relative;
    cursor: pointer;
    padding: 5px 10px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    gap: 6px;
    user-select: none;
}

.lang-switch.active .lang-menu { display: block; }

.lang-menu {
    display: none;
    position: absolute;
    top: calc(100% + 6px);
    right: 0;
    background-color: var(--bg-parchment);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    min-width: 120px;
    box-shadow: 0 6px 16px rgba(0,0,0,0.08);
    padding: 5px 0;
    z-index: 200;
}

.lang-menu li {
    padding: 0;
    font-size: 0.9rem;
    white-space: nowrap;
}

.lang-menu li a {
    display: block;
    padding: 9px 16px;
    text-decoration: none;
    color: var(--text-main);
    transition: background 0.15s, color 0.15s;
}

.lang-menu li a:hover {
    background-color: var(--bg-parchment-dark);
    color: var(--accent-secondary);
}

.lang-menu li a.lang-menu__cur {
    color: var(--accent-primary);
    font-weight: 600;
}

/* ── 移动端平铺语言行 ── */
.lang-row {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 14px 20px;
    flex-wrap: wrap;
    color: var(--text-muted);
    font-size: 0.85rem;
}

.lang-pill {
    display: inline-block;
    padding: 4px 10px;
    border-radius: 20px;
    border: 1px solid var(--border-color);
    font-size: 0.8rem;
    color: var(--text-muted);
    text-decoration: none;
    transition: var(--transition);
}

.lang-pill:hover,
.lang-pill--active {
    background: var(--accent-primary);
    color: #fff;
    border-color: var(--accent-primary);
}

.mobile-menu-btn {
    display: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-main);
}

/* Hero Section */
.hero {
    padding: 100px 0 80px;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(209,199,179,0.3) 0%, rgba(249,245,235,0) 60%);
    z-index: -1;
    pointer-events: none;
}

.hero__badge {
    display: inline-flex;
    align-items: center;
    gap: 7px;
    padding: 6px 16px;
    background: rgba(59,90,74,0.1);
    border: 1px solid rgba(59,90,74,0.25);
    border-radius: 20px;
    font-size: 0.82rem;
    color: var(--accent-primary);
    font-weight: 500;
    margin-bottom: 20px;
    letter-spacing: 0.3px;
}

.hero__badge i { font-size: 0.78rem; }

.hero__title {
    font-family: var(--font-serif);
    font-size: 3.2rem;
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--text-main);
    letter-spacing: 1px;
    line-height: 1.25;
}

.hero__title-sub {
    display: block;
    font-size: 1.8rem;
    font-weight: 400;
    color: var(--accent-primary);
    letter-spacing: 2px;
    margin-top: 6px;
}

.hero__desc {
    font-size: 1.05rem;
    color: var(--text-muted);
    max-width: 680px;
    margin: 0 auto 40px;
    line-height: 1.8;
}

.btn-group {
    display: flex;
    justify-content: center;
    gap: 20px;
}

.btn {
    padding: 12px 30px;
    border-radius: 4px;
    font-size: 1.1rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 8px;
    border: 2px solid transparent;
}

.btn--primary {
    background-color: var(--accent-primary);
    color: #fff;
}

.btn--primary:hover {
    background-color: var(--accent-hover);
    transform: translateY(-2px);
}

.btn--outline {
    background-color: transparent;
    border-color: var(--accent-primary);
    color: var(--accent-primary);
}

.btn--outline:hover {
    background-color: var(--accent-primary);
    color: #fff;
    transform: translateY(-2px);
}

/* Hero Platforms */
.hero-platforms {
    margin-top: 40px;
    display: flex;
    justify-content: center;
    gap: 25px;
    color: var(--text-muted);
    font-size: 1.8rem;
}

.platform-icon {
    transition: var(--transition);
    opacity: 0.7;
}

.platform-icon:hover {
    color: var(--accent-primary);
    opacity: 1;
    transform: translateY(-3px);
}

/* Trust & Stats Section */
.trust {
    background-color: var(--bg-parchment-dark);
    padding: 40px 0;
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
}

.stats-grid {
    display: flex;
    justify-content: center;
    gap: 80px;
    text-align: center;
    flex-wrap: wrap;
}

.stat-item__num {
    font-family: var(--font-serif);
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--accent-secondary);
    margin-bottom: 5px;
}

.stat-item__label {
    font-size: 0.95rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 1px;
}

/* Generic Section Styles */
.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-header__title {
    font-family: var(--font-serif);
    font-size: 2.2rem;
    margin-bottom: 15px;
}

.section-header__subtitle {
    color: var(--text-muted);
    font-size: 1.1rem;
    max-width: 600px;
    margin: 0 auto;
}

/* Features Section */
.features {
    padding: 80px 0;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 40px;
}

.feature-card {
    background: rgba(255, 255, 255, 0.4);
    border: 1px solid var(--border-color);
    padding: 30px;
    border-radius: 8px;
    transition: var(--transition);
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0,0,0,0.05);
    background: rgba(255, 255, 255, 0.6);
    border-color: var(--accent-primary);
}

.feature-card__icon {
    font-size: 2rem;
    color: var(--accent-primary);
    margin-bottom: 20px;
}

.feature-card__title {
    font-size: 1.25rem;
    margin-bottom: 10px;
    font-family: var(--font-serif);
}

.feature-card__desc {
    color: var(--text-muted);
    font-size: 0.95rem;
}

/* Scenarios / Use Cases Section */
.scenarios {
    padding: 80px 0;
    background-color: var(--bg-parchment-dark);
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
}

.scenarios-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.scenario-item {
    display: flex;
    flex-direction: column;
    gap: 15px;
    padding-left: 20px;
    border-left: 3px solid var(--accent-secondary);
}

.scenario-item h3 {
    font-family: var(--font-serif);
    color: var(--accent-primary);
}

.scenario-item p {
    color: var(--text-muted);
    font-size: 0.95rem;
}

/* Work Principle / Architecture */
.architecture {
    padding: 80px 0;
}

.arch-content {
    background: var(--bg-parchment);
    border: 1px dashed var(--accent-primary);
    padding: 40px;
    border-radius: 8px;
    text-align: center;
}

.arch-flow {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
    margin-top: 30px;
    font-family: var(--font-serif);
    font-size: 1.1rem;
    color: var(--accent-primary);
}

.arch-flow span {
    background: rgba(255, 255, 255, 0.5);
    padding: 10px 20px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
}

.arch-flow i {
    color: var(--accent-secondary);
}

/* FAQ Section */
.faq {
    padding: 80px 0;
    background-color: var(--bg-parchment-dark);
    border-top: 1px solid var(--border-color);
}

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

.faq-item {
    background: var(--bg-parchment);
    border: 1px solid var(--border-color);
    margin-bottom: 15px;
    border-radius: 6px;
    overflow: hidden;
}

.faq-item summary {
    padding: 20px;
    font-weight: 500;
    cursor: pointer;
    list-style: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-family: var(--font-serif);
}

.faq-item summary::-webkit-details-marker {
    display: none;
}

.faq-item summary::after {
    content: '\f078'; /* FontAwesome chevron-down */
    font-family: "Font Awesome 6 Free";
    font-weight: 900;
    color: var(--accent-primary);
    transition: var(--transition);
}

.faq-item[open] summary::after {
    transform: rotate(180deg);
}

.faq-item p {
    padding: 0 20px 20px;
    color: var(--text-muted);
    border-top: 1px dashed var(--border-color);
    margin-top: 10px;
    padding-top: 20px;
}

/* Downloads Section */
.downloads {
    padding: 80px 0;
}

.platform-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-top: 40px;
}

.platform-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 35px 20px;
    background-color: rgba(255, 255, 255, 0.4);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
}

.platform-card:hover {
    border-color: var(--accent-primary);
    background-color: var(--bg-parchment-dark);
    transform: translateY(-5px);
}

.platform-card i {
    font-size: 3rem;
    margin-bottom: 15px;
    color: var(--accent-primary);
}

.platform-card span {
    font-weight: 700;
    font-size: 1.1rem;
    margin-bottom: 5px;
    font-family: var(--font-serif);
}

.platform-card small {
    color: var(--text-muted);
    font-size: 0.85rem;
}

/* Footer */
.footer {
    background-color: #2b2722;
    color: #d1c7b3;
    padding: 64px 0 32px;
}

/* ── 主体：品牌 + 链接 ── */
.footer-body {
    display: grid;
    grid-template-columns: 260px 1fr;
    gap: 64px;
    align-items: start;
    margin-bottom: 48px;
}

/* ── 品牌区 ── */
.footer-brand__logo {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    text-decoration: none;
    font-family: var(--font-serif);
    font-size: 1.35rem;
    font-weight: 700;
    color: #fff;
    margin-bottom: 10px;
}

.footer-brand__logo img {
    width: 26px;
    height: 26px;
    object-fit: contain;
}

.footer-brand__tag {
    font-size: 0.72rem;
    letter-spacing: 1.2px;
    text-transform: uppercase;
    color: rgba(255,255,255,0.35);
    margin-bottom: 14px;
}

.footer-brand__desc {
    font-size: 0.86rem;
    color: rgba(255,255,255,0.42);
    line-height: 1.8;
    margin-bottom: 18px;
}

.footer-brand__domain {
    display: inline-block;
    font-size: 0.75rem;
    color: rgba(255,255,255,0.28);
    border: 1px solid rgba(255,255,255,0.1);
    padding: 3px 10px;
    border-radius: 4px;
    letter-spacing: 0.3px;
}

/* ── 链接区 ── */
.footer-links {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
}

.footer-col h5 {
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1.4px;
    color: rgba(255,255,255,0.35);
    margin-bottom: 18px;
    font-family: var(--font-sans);
}

.footer-col ul { list-style: none; }

.footer-col ul li {
    margin-bottom: 11px;
}

.footer-col ul li a {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: rgba(255,255,255,0.52);
    font-size: 0.87rem;
    text-decoration: none;
    transition: color 0.18s;
}

.footer-col ul li a i {
    font-size: 0.7rem;
    width: 13px;
    text-align: center;
    opacity: 0.65;
    flex-shrink: 0;
}

.footer-col ul li a:hover {
    color: #fff;
}

/* ── 底栏 ── */
.footer-bottom {
    border-top: 1px solid rgba(255,255,255,0.07);
    padding-top: 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    flex-wrap: wrap;
    font-size: 0.78rem;
    color: rgba(255,255,255,0.25);
}

/* ── 响应式 ── */
@media (max-width: 900px) {
    .footer-body { grid-template-columns: 1fr; gap: 36px; }
    .footer-links { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 480px) {
    .footer-links { grid-template-columns: 1fr; gap: 24px; }
    .footer-bottom { flex-direction: column; text-align: center; }
}

/* ══════════════════════════════════════════════
   全站响应式断点
   ══════════════════════════════════════════════ */

/* ── 汉堡菜单提前到 900px（导航项增多后防拥挤） ── */
@media (max-width: 900px) {
    /* 收起导航 */
    .nav__links {
        display: none;
        position: absolute;
        top: 70px;
        left: 0;
        width: 100%;
        background-color: var(--bg-parchment);
        flex-direction: column;
        gap: 0;                                   /* 覆盖桌面端 gap:30px */
        padding: 0;
        border-bottom: 2px solid var(--border-color);
        box-shadow: 0 8px 20px rgba(0,0,0,0.07);
        z-index: 999;
    }

    .nav__links.active { display: flex; }

    /* 每个导航项全宽，带下边框分隔 */
    .nav__links > li {
        width: 100%;
        border-bottom: 1px solid var(--border-color);
    }

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

    /* 导航链接全宽点击区 */
    .nav__links > li > a {
        display: block;
        padding: 15px 24px;
        font-size: 1rem;
    }

    /* active 链接在移动端去掉 border-bottom 下划线，改用左边框 */
    .nav__links > li > a.nav__link--active {
        border-bottom: none;
        padding-bottom: 15px;
        border-left: 3px solid var(--accent-primary);
        padding-left: 21px;
    }

    /* 显示汉堡按钮 */
    .mobile-menu-btn { display: block; }

    /* 移动端：隐藏桌面下拉，显示平铺语言行 */
    .nav-lang-desktop { display: none !important; }
    .nav-lang-mobile  { display: block; }
}

/* ── 平板 / 大手机（768px） ── */
@media (max-width: 768px) {
    /* Hero */
    .hero { padding: 60px 0 50px; }
    .hero__badge { font-size: 0.76rem; padding: 5px 12px; }
    .hero__title { font-size: 1.8rem; }
    .hero__title-sub { font-size: 1.2rem; }
    .hero__desc { font-size: 0.95rem; }
    .hero-platforms { gap: 18px; font-size: 1.5rem; margin-top: 28px; }
    .btn-group { flex-direction: column; align-items: center; gap: 12px; }
    .btn-group .btn { width: 100%; max-width: 280px; justify-content: center; }

    /* Stats */
    .trust { padding: 28px 0; }
    .stats-grid { gap: 28px; }
    .stat-item__num { font-size: 2rem; }
    .stat-item__label { font-size: 0.82rem; }

    /* Sections */
    .section-header { margin-bottom: 36px; }
    .section-header__title { font-size: 1.7rem; }
    .section-header__subtitle { font-size: 0.93rem; }
    .features { padding: 52px 0; }
    .scenarios { padding: 52px 0; }
    .architecture { padding: 52px 0; }
    .faq { padding: 52px 0; }
    .downloads { padding: 52px 0; }

    /* Feature cards */
    .feature-card { padding: 22px; }
    .feature-card__icon { font-size: 1.6rem; margin-bottom: 14px; }

    /* Architecture box */
    .arch-content { padding: 22px 16px; }
    .arch-flow { flex-direction: column; gap: 10px; }
    .arch-flow i { transform: rotate(90deg); }
    .arch-flow span { font-size: 0.9rem; padding: 8px 14px; }

    /* FAQ */
    .faq-item summary { padding: 14px 16px; font-size: 0.95rem; }
    .faq-item p { padding: 14px 16px; }

    /* Platform download cards */
    .platform-grid { grid-template-columns: repeat(2, 1fr); gap: 12px; }
    .platform-card { padding: 22px 12px; }
}

/* ── 手机（480px） ── */
@media (max-width: 480px) {
    .hero { padding: 44px 0 38px; }
    .hero__title { font-size: 1.5rem; letter-spacing: 0; }
    .hero__title-sub { font-size: 1rem; }
    .stats-grid { gap: 20px; }
    .stat-item__num { font-size: 1.7rem; }
    .section-header__title { font-size: 1.45rem; }
    .features-grid { gap: 16px; }
    .scenarios-grid { gap: 20px; }
    .platform-grid { grid-template-columns: 1fr 1fr; }
    .download-cta > div { flex-direction: column !important; }
}

/* Download CTA banner on homepage */
.download-cta {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
    margin-top: 40px;
    padding: 24px 32px;
    background: rgba(59,90,74,0.06);
    border: 1px solid rgba(59,90,74,0.2);
    border-radius: 8px;
    flex-wrap: wrap;
}

.download-cta p {
    color: var(--text-muted);
    font-size: 0.95rem;
    margin: 0;
}

@media (max-width: 768px) {
    .download-cta {
        flex-direction: column;
        text-align: center;
        padding: 18px 16px;
        gap: 14px;
    }
}