/*
 * Northern Industrial, LLC - Reimagined Stylesheet
 * Theme: 自然与工业的融合 — Forest-inspired palette with industrial precision
 * Implements WCAG-conscious, mobile-first layout aligned to the design brief.
 */

@import url('https://fonts.googleapis.com/css2?family=Libre+Baskerville:wght@400;700&family=Source+Sans+Pro:wght@400;600;700&display=swap');

:root {
    /* Core palette */
    --color-primary: #1B4332; /* Forest deep green */
    --color-primary-light: #2D5A3D; /* Canopy green */
    --color-secondary: #78350F; /* Wood brown */
    --color-accent: #A16207; /* Oak amber */
    --color-highlight: #D4A574; /* Pine sapwood */
    --color-surface: #FAF8F5; /* Neutral surface */
    --color-paper: #FDFCFA; /* Light paper */
    --color-earth: #F5F0E8; /* Earthy base */
    --color-border: #D8CFC7; /* Subtle border */
    --color-border-strong: #C5B9B0;
    --color-text: #1F2A24; /* Charcoal green */
    --color-text-secondary: #4B5A52;
    --color-text-muted: #6B746E;
    --color-white: #FFFFFF;
    --color-light: #FAF8F5;
    --color-dark: #0F1D17;
    --color-text-light: #FFFFFF;

    /* Spacing scale */
    --space-xs: 0.25rem;   /* 4px */
    --space-sm: 0.5rem;    /* 8px */
    --space-md: 1rem;      /* 16px */
    --space-lg: 1.5rem;    /* 24px */
    --space-xl: 2rem;      /* 32px */
    --space-2xl: 3rem;     /* 48px */
    --space-3xl: 4rem;     /* 64px */

    /* Radius & shadow */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 14px;
    --border-radius-sm: var(--radius-sm);
    --border-radius-md: var(--radius-md);
    --shadow-sm: 0 8px 18px rgba(15, 29, 23, 0.06);
    --shadow-md: 0 14px 32px rgba(15, 29, 23, 0.12);
    --shadow-lg: 0 22px 46px rgba(15, 29, 23, 0.18);

    /* Typography */
    --font-heading: 'Libre Baskerville', 'Georgia', serif;
    --font-body: 'Source Sans Pro', 'Segoe UI', system-ui, sans-serif;
    --font-size-base: 1rem;
    --font-size-small: 0.95rem;
    --font-size-h1: 2.75rem;
    --font-size-h2: 2.1rem;
    --font-size-h3: 1.5rem;
    --font-size-h4: 1.2rem;

    /* Layout */
    --container-max: 1200px;
    --nav-height: 76px;
    --transition: 180ms ease;
}

/* Reset & base */
* { box-sizing: border-box; }
*::before, *::after { box-sizing: inherit; }

body {
    margin: 0;
    font-family: var(--font-body);
    font-size: var(--font-size-base);
    line-height: 1.65;
    color: var(--color-text);
    background: var(--color-paper);
    -webkit-font-smoothing: antialiased;
    padding-top: var(--nav-height);
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    color: var(--color-primary);
    margin: 0 0 var(--space-sm) 0;
    line-height: 1.2;
}

h1 { font-size: var(--font-size-h1); }
h2 { font-size: var(--font-size-h2); }
h3 { font-size: var(--font-size-h3); }
h4 { font-size: var(--font-size-h4); }

p { margin: 0 0 var(--space-md) 0; color: var(--color-text-secondary); }

ul, ol { margin: 0 0 var(--space-md) 1.25rem; color: var(--color-text-secondary); }
li { margin-bottom: 0.25rem; }

img { max-width: 100%; display: block; border-radius: var(--radius-md); }

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

.container {
    width: min(var(--container-max), 92%);
    margin: 0 auto;
}

.section {
    padding: var(--space-2xl) 0;
}

.section.alt { background: var(--color-surface); }

.section-title {
    font-size: var(--font-size-h2);
    margin-bottom: var(--space-md);
    letter-spacing: 0.01em;
}

.text-lead { font-size: 1.1rem; color: var(--color-text); }

.eyebrow {
    text-transform: uppercase;
    letter-spacing: 0.08em;
    font-size: 0.85rem;
    color: var(--color-secondary);
    font-weight: 700;
    margin-bottom: var(--space-sm);
}

.muted { color: var(--color-text-muted); }

/* Accessibility */
.skip-link {
    position: absolute;
    left: -999px;
    top: 12px;
    padding: var(--space-sm) var(--space-md);
    background: var(--color-primary);
    color: var(--color-white);
    z-index: 2000;
    border-radius: var(--radius-sm);
    text-decoration: none;
}

.skip-link:focus { left: 12px; box-shadow: var(--shadow-md); }

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.7rem 1.2rem;
    border-radius: var(--radius-md);
    border: 1px solid transparent;
    font-weight: 700;
    letter-spacing: 0.01em;
    text-decoration: none;
    transition: transform var(--transition), box-shadow var(--transition), background var(--transition), color var(--transition);
    cursor: pointer;
    white-space: nowrap;
}

.btn-primary {
    background: var(--color-primary);
    color: var(--color-white);
    border-color: var(--color-primary);
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover { transform: translateY(-1px); box-shadow: var(--shadow-md); background: #163626; }

.btn-secondary {
    background: var(--color-secondary);
    color: var(--color-white);
    border-color: var(--color-secondary);
}

.btn-secondary:hover { background: #5e2a0c; }

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

.btn-ghost:hover { border-color: var(--color-primary); color: var(--color-primary); box-shadow: var(--shadow-sm); }

/* Tags & badges */
.badge {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.35rem 0.65rem;
    border-radius: 999px;
    background: var(--color-earth);
    color: var(--color-primary);
    font-weight: 600;
    font-size: 0.9rem;
    border: 1px solid var(--color-border);
}

.badge-cert { background: #E3E0DA; border-color: var(--color-border-strong); }

.badge-outline { background: transparent; border: 1px solid var(--color-border); color: var(--color-text-secondary); }

.pill {
    display: inline-block;
    padding: 0.35rem 0.75rem;
    border-radius: 999px;
    background: var(--color-primary-light);
    color: var(--color-white);
    font-weight: 600;
    font-size: 0.85rem;
}

/* Layout helpers */
.grid {
    display: grid;
    gap: var(--space-lg);
    margin: var(--space-lg) 0;
}

.grid-2-col { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.grid-3-col { grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); }
.grid-3-col.nowrap { grid-auto-flow: column; grid-auto-columns: 1fr; overflow-x: auto; }
.grid-4-col { grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); }

.split {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-xl);
    align-items: center;
}

.card {
    background: var(--color-paper);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    overflow: hidden;
    display: flex;
    flex-direction: column;
    height: 100%;
}

.card-header { padding: var(--space-md); border-bottom: 1px solid var(--color-border); background: linear-gradient(135deg, rgba(27,67,50,0.08), rgba(27,67,50,0)); }

.card-image { width: 100%; height: 210px; object-fit: cover; }

.card-content { padding: var(--space-md); flex: 1; display: flex; flex-direction: column; gap: var(--space-sm); }

.card-content a { font-weight: 700; color: var(--color-primary); }

.grid-item {
    background: var(--color-paper);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-md);
    box-shadow: var(--shadow-sm);
}

.stat-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: var(--space-md);
}

.stat {
    padding: var(--space-md);
    background: var(--color-earth);
    border-radius: var(--radius-md);
    border: 1px solid var(--color-border);
    text-align: center;
    box-shadow: var(--shadow-sm);
}

.stat strong { display: block; font-size: 1.4rem; color: var(--color-primary); margin-bottom: 0.35rem; }

.feature-panel {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-xl);
    align-items: center;
}

.feature-panel .media { border-radius: var(--radius-lg); overflow: hidden; box-shadow: var(--shadow-md); }

.feature-panel .content { display: flex; flex-direction: column; gap: var(--space-sm); }

.checklist { list-style: none; padding: 0; margin: 0; }

.checklist li { display: flex; gap: 0.5rem; align-items: flex-start; margin-bottom: 0.6rem; color: var(--color-text-secondary); }

.checklist li::before { content: "✓"; color: var(--color-primary); font-weight: 700; margin-top: 0.15rem; }

/* Header & navigation */
.site-header, .header {
    position: fixed;
    top: 0; left: 0; right: 0;
    height: var(--nav-height);
    background: rgba(27, 67, 50, 0.97);
    backdrop-filter: blur(6px);
    box-shadow: var(--shadow-md);
    z-index: 1000;
}

.nav-container {
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-md);
    width: min(var(--container-max), 96%);
    margin: 0 auto;
}

.logo a, .brand a {
    color: var(--color-white);
    font-family: var(--font-heading);
    font-size: 1.15rem;
    text-decoration: none;
    letter-spacing: 0.01em;
    display: inline-flex;
    align-items: baseline;
    gap: 0.5rem;
    line-height: 1;
    white-space: nowrap;
}

.logo small { font-family: var(--font-body); font-size: 0.8rem; color: rgba(255,255,255,0.82); font-weight: 600; }

.menu-toggle {
    background: transparent;
    border: 1px solid rgba(255,255,255,0.35);
    color: var(--color-white);
    padding: 0.5rem 0.65rem;
    border-radius: var(--radius-md);
    cursor: pointer;
    display: none;
}

nav { position: relative; }

.nav-menu {
    list-style: none;
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    margin: 0;
    padding: 0;
}

.nav-item { position: relative; }

.nav-link {
    color: var(--color-white);
    padding: 0.45rem 0.65rem;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 0.9rem;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
}

.nav-link:hover, .nav-link:focus { background: rgba(255,255,255,0.08); }

.sub-menu {
    display: none;
    position: absolute;
    top: calc(100% + 6px);
    left: 0;
    min-width: 220px;
    background: var(--color-paper);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
    list-style: none;
    padding: var(--space-sm);
    z-index: 20;
}

.sub-menu li { margin: 0; }

.sub-menu a {
    color: var(--color-text);
    display: block;
    padding: 0.45rem 0.6rem;
    border-radius: var(--radius-sm);
    font-weight: 600;
}

.sub-menu a:hover { background: var(--color-earth); color: var(--color-primary); }

.nav-item:hover > .sub-menu, .nav-item:focus-within > .sub-menu { display: block; }

.nav-actions { display: flex; align-items: center; gap: var(--space-sm); }
.nav-cta-mobile { display: none; }

/* Hero */
.hero {
    position: relative;
    min-height: 60vh;
    display: grid;
    place-items: center;
    color: var(--color-white);
    overflow: hidden;
    border-bottom: 1px solid var(--color-border-strong);
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
}

.hero::after {
    content: "";
    position: absolute;
    inset: 0;
    background: linear-gradient(120deg, rgba(27,67,50,0.78), rgba(27,67,50,0.35));
    z-index: 1;
}

.hero .hero-overlay { display: none; }

.hero-content {
    position: relative;
    z-index: 2;
    width: min(960px, 90%);
    text-align: left;
}

.hero-content h1 { color: var(--color-white); margin-bottom: var(--space-sm); }
.hero-content p { color: rgba(255,255,255,0.92); font-size: 1.05rem; }

.hero-actions { display: flex; flex-wrap: wrap; gap: var(--space-sm); margin-top: var(--space-md); }

.hero-badges { display: flex; flex-wrap: wrap; gap: var(--space-sm); margin-top: var(--space-sm); }

/* Feature stripes */
.strip {
    background: linear-gradient(135deg, rgba(120,53,15,0.08), rgba(27,67,50,0.08));
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-lg);
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--space-md);
    box-shadow: var(--shadow-sm);
}

.strip .item { display: flex; flex-direction: column; gap: 0.35rem; }

/* Lists */
.highlight-list { list-style: none; padding: 0; margin: 0; }
.highlight-list li {
    padding: 0.6rem 0;
    border-bottom: 1px solid var(--color-border);
    color: var(--color-text-secondary);
    display: flex; justify-content: space-between; gap: var(--space-sm);
}

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

/* Footer */
.footer, .site-footer {
    background: var(--color-earth);
    border-top: 1px solid var(--color-border-strong);
    margin-top: var(--space-2xl);
    padding: var(--space-2xl) 0 var(--space-xl);
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: var(--space-lg);
    margin-bottom: var(--space-lg);
}

.footer-column h4 { margin-bottom: var(--space-sm); color: var(--color-primary); }

.footer-column ul { list-style: none; padding: 0; margin: 0; }

.footer-column li { margin-bottom: 0.45rem; }

.footer-column a { color: var(--color-text); font-weight: 600; }

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

.cert-row {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
    margin-bottom: var(--space-md);
}

.footer-bottom {
    border-top: 1px solid var(--color-border);
    padding-top: var(--space-md);
    color: var(--color-text-muted);
    font-size: 0.95rem;
}

/* Tables & forms */
.table { width: 100%; border-collapse: collapse; }
.table th, .table td { padding: 0.75rem; border-bottom: 1px solid var(--color-border); text-align: left; }
.table th { color: var(--color-primary); }

form { display: grid; gap: var(--space-md); }

label { font-weight: 700; color: var(--color-text); margin-bottom: 0.2rem; display: block; }

input, select, textarea {
    width: 100%;
    padding: 0.75rem 0.85rem;
    border-radius: var(--radius-md);
    border: 1px solid var(--color-border);
    background: var(--color-paper);
    font-family: var(--font-body);
    font-size: 1rem;
    transition: border-color var(--transition), box-shadow var(--transition);
}

input:focus, select:focus, textarea:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(27, 67, 50, 0.15);
}

textarea { min-height: 160px; resize: vertical; }

/* News cards */
.news-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: var(--space-lg); }

.news-card { border: 1px solid var(--color-border); border-radius: var(--radius-lg); overflow: hidden; background: var(--color-paper); box-shadow: var(--shadow-sm); display: flex; flex-direction: column; }

.news-card img { height: 180px; object-fit: cover; }

.news-card .content { padding: var(--space-md); display: flex; flex-direction: column; gap: var(--space-sm); flex: 1; }

.news-card time { font-size: 0.9rem; color: var(--color-text-muted); }

/* Utility classes */
.text-center { text-align: center; }
.text-right { text-align: right; }

.kpi-bar {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: var(--space-md);
    margin-top: var(--space-md);
}

.kpi {
    padding: var(--space-md);
    background: var(--color-paper);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
}

.kpi strong { display: block; font-size: 1.4rem; color: var(--color-primary); }

/* Responsive navigation */
@media (max-width: 1024px) {
    .nav-menu {
        position: absolute;
        right: 0;
        top: var(--nav-height);
        background: rgba(27, 67, 50, 0.98);
        flex-direction: column;
        align-items: flex-start;
        padding: var(--space-md);
        border-radius: var(--radius-md);
        width: min(320px, 92vw);
        border: 1px solid rgba(255,255,255,0.15);
        box-shadow: var(--shadow-lg);
        display: none;
    }

    .nav-menu.active { display: flex; }

    .menu-toggle { display: inline-flex; }

    .nav-actions { display: none; }
    .nav-cta-mobile { display: block; width: 100%; }

    .sub-menu { position: static; width: 100%; border: none; box-shadow: none; background: transparent; padding: 0.25rem 0 0 0; }
    .sub-menu a { padding-left: 0; color: rgba(255,255,255,0.9); }
}

@media (max-width: 768px) {
    body { padding-top: var(--nav-height); }
    .hero { min-height: 55vh; }
    .hero-content { text-align: left; }
    .section { padding: var(--space-xl) 0; }
}

@media (min-width: 1025px) {
    .nav-actions { display: flex; }
    .nav-cta-mobile { display: none; }
}