:root {
    --green-primary: #5B7B5B;
    --green-light: #E6EDE6;
    --green-hover: #4A6A4A;
    --green-subtle: #F2F6F2;
    --text-dark: #1F1F1F;
    --text-body: #3A3A3A;
    --text-muted: #6B6B6B;
    --text-light: #999999;
    --border: #D8D8D8;
    --border-light: #ECECEC;
    --white: #FFFFFF;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.08);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.10);
    --radius: 4px;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --font-display: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
    --font-body: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
    --max-width: 1200px;
}

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

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-body);
    background-color: var(--white);
    color: var(--text-body);
    line-height: 1.8;
    overflow-x: hidden;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* ── Navigation ── */
.site-nav {
    background: var(--white);
    border-bottom: 1px solid var(--border-light);
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(12px);
    background: rgba(255,255,255,0.95);
}

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

.nav-brand {
    font-family: var(--font-display);
    font-size: 20px;
    font-weight: 600;
    color: var(--text-dark);
    text-decoration: none;
    letter-spacing: 2px;
    position: relative;
}

.nav-brand::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--green-primary);
    transform: scaleX(0);
    transform-origin: right;
    transition: transform var(--transition);
}

.nav-brand:hover::after {
    transform: scaleX(1);
    transform-origin: left;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 8px;
    list-style: none;
}

.nav-links a {
    font-size: 15px;
    color: var(--text-muted);
    text-decoration: none;
    padding: 8px 18px;
    border-radius: var(--radius);
    transition: color var(--transition), background var(--transition);
    letter-spacing: 0.5px;
    position: relative;
}

.nav-links a:hover {
    color: var(--green-primary);
    background: var(--green-subtle);
}

.nav-links a.active {
    color: var(--green-primary);
    font-weight: 600;
}

.nav-links a.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 18px;
    right: 18px;
    height: 2px;
    background: var(--green-primary);
    border-radius: 1px;
}

.nav-mobile-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.nav-mobile-toggle span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--text-dark);
    margin: 5px 0;
    transition: var(--transition);
    border-radius: 1px;
}

/* ── Main Content ── */
main {
    flex: 1;
}

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

/* ── Footer ── */
.site-footer {
    margin-top: auto;
}

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

.footer-divider hr {
    border: none;
    height: 1px;
    background: var(--border);
}

.footer-content {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 20px 24px 28px;
    text-align: center;
}

.footer-copyright {
    font-size: 13px;
    color: var(--text-muted);
    margin-bottom: 6px;
    letter-spacing: 0.5px;
}

.footer-icp {
    font-size: 12px;
}

.footer-icp a {
    color: var(--text-light);
    text-decoration: none;
    transition: color var(--transition);
}

.footer-icp a:hover {
    color: var(--green-primary);
}

/* ── Utilities ── */
.section-title {
    font-family: var(--font-display);
    font-size: 28px;
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: 12px;
    letter-spacing: 2px;
}

.section-subtitle {
    font-size: 15px;
    color: var(--text-muted);
    margin-bottom: 40px;
}

.section-divider {
    width: 40px;
    height: 2px;
    background: var(--green-primary);
    margin-bottom: 24px;
}

/* ── Responsive ── */
@media (max-width: 768px) {
    .nav-inner {
        height: 60px;
    }

    .nav-brand {
        font-size: 16px;
    }

    .nav-links {
        display: none;
        position: absolute;
        top: 60px;
        left: 0;
        right: 0;
        background: var(--white);
        flex-direction: column;
        padding: 16px 24px;
        border-bottom: 1px solid var(--border-light);
        box-shadow: var(--shadow-md);
        gap: 4px;
    }

    .nav-links.open {
        display: flex;
    }

    .nav-links a {
        padding: 12px 16px;
        width: 100%;
    }

    .nav-links a.active::after {
        left: 0;
        right: auto;
        width: 3px;
        height: 20px;
        top: 50%;
        transform: translateY(-50%);
        bottom: auto;
    }

    .nav-mobile-toggle {
        display: block;
    }

    .section-title {
        font-size: 22px;
    }

    .container {
        padding: 0 16px;
    }
}

@media (max-width: 480px) {
    .nav-brand {
        font-size: 14px;
        letter-spacing: 1px;
    }
}

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

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.animate-fade-in-up {
    animation: fadeInUp 0.6s ease-out both;
}

.animate-fade-in {
    animation: fadeIn 0.6s ease-out both;
}