:root {
            --header-bg: #1a1f2e;
            --header-text: #ffffff;
            --bg-primary: #ffffff;
            --bg-secondary: #f8f9fa;
            --bg-card: #ffffff;
            --text-primary: #1a202c;
            --text-secondary: #4a5568;
            --text-muted: #718096;
            --accent-teal: #2b6cb0;
            --accent-coral: #996060;
            --accent-warm: #c05621;
            --accent-green: #2f855a;
            --border: #e2e8f0;
            --shadow: 0 1px 3px rgba(0,0,0,0.08);
            --manza: #c05621;
            --sesoko: #2b6cb0;
            --ogasawara: #2f855a;
            --kushimoto: #805ad5;
            --amami: #d53f8c;
            --kerama: #0891b2;
            --sekisei: #e53e3e;
            --alert-bg: #fef2f2;
            --alert-border: #c05621;
            --warning-bg: #fffbeb;
            --warning-border: #d69e2e;
            --hot-color: #dc2626;
        }

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

        body {
            font-family: 'DM Sans', 'Noto Sans JP', sans-serif;
            background: var(--bg-secondary);
            color: var(--text-primary);
            line-height: 1.6;
            min-height: 100vh;
        }

        body.ja {
            font-family: 'Noto Sans JP', 'DM Sans', sans-serif;
        }

        header {
            background: var(--header-bg);
            color: var(--header-text);
            padding: 0.75rem 2rem;
            position: sticky;
            top: 0;
            z-index: 100;
        }

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

        .logo {
            font-weight: 600;
            font-size: 0.95rem;
            display: flex;
            align-items: center;
            gap: 0.75rem;
            text-decoration: none;
            color: inherit;
        }

        .logo-icon {
            overflow: hidden;
            width: 28px;
            height: 28px;
            background: linear-gradient(135deg, #5b9a94 0%, #2b6cb0 100%);
            border-radius: 6px;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 0.75rem;
        }

        .header-controls {
            display: flex;
            align-items: center;
            gap: 1rem;
        }

        .lang-switch {
            font-size: 0.8rem;
            display: flex;
            gap: 0.25rem;
        }

        .lang-switch button {
            background: none;
            border: none;
            color: rgba(255,255,255,0.6);
            cursor: pointer;
            font-size: 0.8rem;
            padding: 0.25rem 0.5rem;
            border-radius: 4px;
            transition: all 0.2s;
        }

        .lang-switch button:hover { color: rgba(255,255,255,0.9); }
        .lang-switch button.active { color: #ffffff; background: rgba(255,255,255,0.15); }

        main {
            max-width: 900px;
            margin: 0 auto;
            padding: 2.5rem 2rem;
        }

        .breadcrumb {
            font-size: 0.8rem;
            color: var(--text-muted);
            margin-bottom: 1.5rem;
        }

        .breadcrumb a {
            color: var(--accent-teal);
            text-decoration: none;
        }

        .breadcrumb a:hover { text-decoration: underline; }

        .page-header {
            margin-bottom: 2.5rem;
        }

        .page-header h1 {
            font-size: 1.75rem;
            font-weight: 600;
            letter-spacing: -0.02em;
            margin-bottom: 0.75rem;
        }

        body.ja .page-header h1 {
            font-size: 1.5rem;
            letter-spacing: 0;
        }

        .page-header .lead {
            font-size: 1rem;
            color: var(--text-secondary);
            line-height: 1.8;
            max-width: 720px;
        }

        body.ja .page-header .lead {
            line-height: 2;
        }

        .card {
            background: var(--bg-card);
            border: 1px solid var(--border);
            border-radius: 8px;
            padding: 1.5rem;
            margin-bottom: 1.5rem;
            box-shadow: var(--shadow);
        }

        .card-title {
            font-size: 0.9rem;
            font-weight: 600;
            color: var(--text-primary);
            margin-bottom: 1rem;
            padding-bottom: 0.75rem;
            border-bottom: 1px solid var(--border);
        }

        /* Alert card for 2024 */
        .alert-card {
            background: var(--alert-bg);
            border: 1px solid var(--alert-border);
            border-left: 4px solid var(--alert-border);
        }

        .alert-card .card-title {
            color: var(--accent-warm);
        }

        /* DHW level indicators */
        .dhw-levels {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 1rem;
            margin: 1rem 0;
        }

        .dhw-level {
            padding: 1rem;
            border-radius: 6px;
            text-align: center;
        }

        .dhw-level.watch {
            background: #fefce8;
            border: 1px solid #facc15;
        }

        .dhw-level.warning {
            background: #fff7ed;
            border: 1px solid #f97316;
        }

        .dhw-level.alert1 {
            background: #fef2f2;
            border: 1px solid #ef4444;
        }

        .dhw-level.alert2 {
            background: #fdf2f8;
            border: 1px solid #be185d;
        }

        .dhw-level .level-name {
            font-size: 0.7rem;
            font-weight: 600;
            text-transform: uppercase;
            letter-spacing: 0.05em;
            margin-bottom: 0.25rem;
        }

        .dhw-level .level-value {
            font-family: 'JetBrains Mono', monospace;
            font-size: 1.25rem;
            font-weight: 600;
        }

        .dhw-level .level-desc {
            font-size: 0.7rem;
            color: var(--text-muted);
            margin-top: 0.25rem;
        }

        /* KPI comparison */
        .kpi-comparison {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 1rem;
            margin: 1rem 0;
        }

        @media (max-width: 640px) {
            .kpi-comparison { grid-template-columns: 1fr; }
        }

        .kpi-item {
            text-align: center;
            padding: 1rem;
            border-radius: 6px;
            background: var(--bg-secondary);
        }

        .kpi-item.highlight {
            background: #fef2f2;
            border: 1px solid var(--accent-warm);
        }

        .kpi-item .site-name {
            font-size: 0.75rem;
            color: var(--text-muted);
            margin-bottom: 0.35rem;
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 0.4rem;
        }

        .site-dot {
            width: 8px;
            height: 8px;
            border-radius: 50%;
        }

        .kpi-item .value {
            font-family: 'JetBrains Mono', monospace;
            font-size: 1.75rem;
            font-weight: 500;
            color: var(--text-primary);
        }

        .kpi-item.highlight .value {
            color: var(--accent-warm);
        }

        .kpi-item .context {
            font-size: 0.7rem;
            color: var(--text-muted);
            margin-top: 0.25rem;
        }

        .content-section {
            margin-bottom: 2rem;
        }

        .content-section h2 {
            font-size: 1.1rem;
            font-weight: 600;
            margin-bottom: 1rem;
            color: var(--text-primary);
        }

        .content-section h3 {
            font-size: 0.95rem;
            font-weight: 600;
            margin: 1.5rem 0 0.75rem;
            color: var(--text-secondary);
        }

        .content-section p {
            color: var(--text-secondary);
            line-height: 1.9;
            margin-bottom: 1rem;
        }

        body.ja .content-section p {
            line-height: 2.1;
        }

        .chart-container {
            height: 300px;
            position: relative;
        }

        .chart-legend {
            display: flex;
            justify-content: center;
            gap: 1.5rem;
            margin-top: 1rem;
            flex-wrap: wrap;
        }

        .legend-item {
            display: flex;
            align-items: center;
            gap: 0.4rem;
            font-size: 0.75rem;
            color: var(--text-secondary);
        }

        .legend-line {
            width: 16px;
            height: 3px;
            border-radius: 2px;
        }

        .legend-manza { background: var(--manza); }
        .legend-sesoko { background: var(--sesoko); }
        .legend-ogasawara { background: var(--ogasawara); }
        .legend-kushimoto { background: var(--kushimoto); }
        .legend-amami { background: var(--amami); }
        .legend-kerama { background: var(--kerama); }
        .legend-sekisei { background: var(--sekisei); }

        /* Reference table */
        .ref-table {
            width: 100%;
            border-collapse: collapse;
            font-size: 0.8rem;
        }

        .ref-table th, .ref-table td {
            padding: 0.6rem 0.75rem;
            text-align: left;
            border-bottom: 1px solid var(--border);
        }

        .ref-table th {
            font-weight: 600;
            color: var(--text-primary);
            background: var(--bg-secondary);
        }

        .ref-table td {
            color: var(--text-secondary);
        }

        .source-info {
            font-size: 0.75rem;
            color: var(--text-muted);
            padding: 1rem;
            background: var(--bg-secondary);
            border-radius: 6px;
            margin-top: 1rem;
        }

        .source-info a {
            color: var(--accent-teal);
            text-decoration: none;
        }

        .source-info a:hover { text-decoration: underline; }

        /* Observation box */
        .observation-box {
            background: linear-gradient(135deg, #fef3c7 0%, #fde68a 100%);
            border: 1px solid #d69e2e;
            border-radius: 8px;
            padding: 1.25rem;
            margin: 1.5rem 0;
        }

        .observation-box .obs-title {
            font-size: 0.8rem;
            font-weight: 600;
            color: #92400e;
            margin-bottom: 0.5rem;
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }

        .observation-box p {
            color: #78350f;
            font-size: 0.85rem;
            line-height: 1.7;
            margin: 0;
        }

        footer {
            max-width: 900px;
            margin: 0 auto;
            padding: 2rem;
            text-align: center;
            font-size: 0.75rem;
            color: var(--text-muted);
            border-top: 1px solid var(--border);
        }

        footer a {
            color: var(--accent-teal);
            text-decoration: none;
        }

        [data-lang="ja"] { display: none; }
        body.ja [data-lang="en"] { display: none; }
        body.ja [data-lang="ja"] { display: inline; }

        /* Threshold line annotation */
        .threshold-note {
            font-size: 0.7rem;
            color: var(--text-muted);
            text-align: center;
            margin-top: 0.5rem;
        }

        /* Hero Section */
        .hero-section {
            background: linear-gradient(135deg, rgba(0,0,0,0.25), rgba(0,0,0,0.25)), url("../images/bg-dhw.webp");
            color: white;
            padding: 2.5rem 2rem;
            border-radius: 12px;
            margin-bottom: 2.5rem;
            background-size: cover;
            background-position: center;
        }
        .hero-main { text-align: center; margin-bottom: 1.5rem; }
        .hero-icon { font-size: 3.5rem; margin-bottom: 0.75rem; }
        .hero-tagline {
            font-size: 1.5rem;
            font-weight: 600;
            margin-bottom: 1rem;
        }
        body.ja .hero-tagline { font-size: 1.3rem; }
        .hero-subtitle {
            font-size: 1rem;
            opacity: 0.9;
            margin-bottom: 1rem;
        }
        .hero-stats-row {
            display: flex;
            justify-content: center;
            gap: 2rem;
            margin-top: 1.5rem;
            flex-wrap: wrap;
        }
        .hero-stat-card {
            background: rgba(255,255,255,0.15);
            border-radius: 8px;
            padding: 1rem 1.5rem;
            text-align: center;
        }
        .hero-stat-card .number {
            font-family: 'JetBrains Mono', monospace;
            font-size: 1.75rem;
            font-weight: 600;
            display: block;
        }
        .hero-stat-card .label {
            font-size: 0.85rem;
            opacity: 0.9;
            margin-top: 0.25rem;
        }
        .hero-stat-card .site-name-hero {
            font-size: 0.75rem;
            opacity: 0.8;
            margin-bottom: 0.25rem;
        }

        /* DHW年別表示 */
        .dhw-year-values {
            display: flex;
            flex-direction: column;
            gap: 0.25rem;
        }
        .dhw-year-row {
            display: flex;
            align-items: baseline;
            justify-content: center;
            gap: 0.3rem;
        }
        .dhw-year-row .year-label {
            font-size: 0.7rem;
            opacity: 0.7;
            min-width: 40px;
            text-align: right;
        }
        .dhw-year-row .number {
            font-size: 1.25rem;
        }
        .dhw-year-row.current .number {
            color: #fbbf24;
        }
        .hero-date-info {
            text-align: center;
            margin-top: 1rem;
            font-size: 0.8rem;
            opacity: 0.8;
        }

        /* Story box */
        .story-box {
            background: #fffbeb;
            border: 1px solid #fde68a;
            border-radius: 8px;
            padding: 1.5rem;
            margin-bottom: 2rem;
        }
        .story-box .story-lead {
            font-size: 1.1rem;
            font-weight: 500;
            color: var(--text-primary);
            margin-bottom: 1rem;
            line-height: 1.7;
        }
        .story-box p {
            font-size: 0.95rem;
            color: var(--text-secondary);
            margin-bottom: 1rem;
            line-height: 1.9;
        }
        .story-box p:last-child { margin-bottom: 0; }

        /* Insight cards */
        .insight-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
            gap: 1.5rem;
            margin-bottom: 2rem;
        }
        .insight-card {
            background: var(--bg-card);
            border: 1px solid var(--border);
            border-radius: 8px;
            padding: 1.5rem;
            box-shadow: var(--shadow);
        }
        .insight-card.limitation { border-left: 4px solid #f59e0b; }
        .insight-card.acclimatization { border-left: 4px solid var(--accent-green); }
        .insight-card h3 {
            font-size: 0.95rem;
            font-weight: 600;
            margin-bottom: 0.75rem;
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }
        .insight-card.limitation h3 { color: #d97706; }
        .insight-card.acclimatization h3 { color: var(--accent-green); }
        .insight-card p {
            font-size: 0.85rem;
            color: var(--text-secondary);
            line-height: 1.8;
        }
        .insight-card .citation {
            font-size: 0.75rem;
            color: var(--text-muted);
            margin-top: 0.75rem;
            font-style: italic;
        }

        /* References section */
        .references-section { margin-top: 2rem; }
        .references-section h2 {
            font-size: 1.1rem;
            font-weight: 600;
            margin-bottom: 1.5rem;
            color: var(--text-primary);
        }
        .ref-category { margin-bottom: 1.5rem; }
        .ref-category h3 {
            font-size: 0.9rem;
            font-weight: 600;
            color: var(--accent-teal);
            margin-bottom: 0.75rem;
            padding-bottom: 0.5rem;
            border-bottom: 1px solid var(--border);
        }
        .ref-list { list-style: none; }
        .ref-list li {
            font-size: 0.8rem;
            color: var(--text-secondary);
            padding: 0.5rem 0;
            line-height: 1.6;
        }
        .ref-list a {
            color: var(--accent-teal);
            text-decoration: none;
        }
        .ref-list a:hover { text-decoration: underline; }

        /* SVG Diagram */
        .diagram-container {
            background: var(--bg-card);
            border: 1px solid var(--border);
            border-radius: 8px;
            padding: 1.5rem;
            margin: 1.5rem 0;
            box-shadow: var(--shadow);
        }
        .diagram-caption {
            font-size: 0.75rem;
            color: var(--text-muted);
            text-align: center;
            margin-top: 0.75rem;
        }

/* Mobile-optimized background images */
@media (max-width: 768px) {
    .hero-section {
        background: linear-gradient(135deg, rgba(0,0,0,0.25), rgba(0,0,0,0.25)), url("../images/bg-dhw-mobile.webp") !important;
        background-size: cover !important;
        background-position: center !important;
    }
}

/* Hero groups for 7 sites */
.hero-group {
    margin-bottom: 1.25rem;
}
.hero-group-label {
    font-size: 0.75rem;
    opacity: 0.8;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 0.75rem;
    text-align: center;
}
.hero-stats-row.hero-stats-2 {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
    max-width: 400px;
    margin: 0 auto;
}
.hero-stats-row.hero-stats-5 {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 0.75rem;
}
.hero-stat-card {
    border-left: 3px solid rgba(255,255,255,0.5);
}
@media (max-width: 768px) {
    .hero-stats-row.hero-stats-5 {
        grid-template-columns: repeat(2, 1fr);
    }
    .hero-stats-row.hero-stats-5 .hero-stat-card:last-child {
        grid-column: span 2;
        max-width: 200px;
        margin: 0 auto;
    }
    .hero-stat-card {
        padding: 0.75rem 1rem;
    }
    .dhw-year-row .number {
        font-size: 1.25rem;
    }
}

/* Calculation Notice Section */
.calculation-notice {
    background: linear-gradient(135deg, #fef3c7 0%, #fde68a 100%);
    border: 2px solid #f59e0b;
    border-radius: 12px;
    padding: 1.5rem;
    margin: 2rem 0;
}

.calculation-notice h2 {
    color: #92400e;
    margin-bottom: 1rem;
}

.calculation-notice h3 {
    color: #78350f;
    font-size: 0.95rem;
    margin-bottom: 0.5rem;
}

.notice-box, .method-box, .caution-box {
    background: rgba(255,255,255,0.7);
    border-radius: 8px;
    padding: 1rem;
    margin-bottom: 1rem;
}

.method-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 0.75rem;
    font-size: 0.85rem;
}

.method-table th, .method-table td {
    padding: 0.5rem;
    border: 1px solid #d97706;
    text-align: left;
}

.method-table th {
    background: #fbbf24;
    color: #78350f;
}

.method-table td {
    background: rgba(255,255,255,0.8);
}

.caution-box ul {
    margin: 0;
    padding-left: 1.25rem;
}

.caution-box li {
    margin-bottom: 0.5rem;
    line-height: 1.6;
}

.caution-box strong {
    color: #92400e;
}

/* Alert Note */
.alert-note {
    margin-top: 1rem;
    padding: 0.75rem 1rem;
    background: #fef3c7;
    border-left: 3px solid #f59e0b;
    border-radius: 4px;
    font-size: 0.85rem;
    color: #78350f;
    line-height: 1.6;
}

.alert-note strong {
    color: #92400e;
}

/* Data Note in Hero */
.data-note {
    margin-top: 0.5rem;
    font-size: 0.75rem;
    color: var(--text-tertiary, #9ca3af);
    opacity: 0.8;
}