/* ============== CSS BREATH-ALGORITHMS-HUB.CSS ============== */
        :root {
            --bg-deep: #08080f;
            --bg-primary: #0c0c14;
            --bg-card: #12121d;
            --bg-card-hover: #181825;
            --bg-elevated: #1a1a2c;
            --bg-modal: #0a0a14;
            --text-primary: #e6e6f0;
            --text-secondary: #b8b8cc;
            --text-tertiary: #7a7a94;
            --accent-red: #c0392b;
            --accent-crimson: #e74c3c;
            --accent-gold: #d4a853;
            --accent-amber: #f0c060;
            --accent-teal: #2eccac;
            --accent-cool: #4a9eb5;
            --accent-purple: #8e44ad;
            --border-subtle: rgba(255, 255, 255, 0.06);
            --border-medium: rgba(255, 255, 255, 0.12);
            --shadow-card: 0 4px 30px rgba(0, 0, 0, 0.6);
            --shadow-glow-red: 0 0 40px rgba(192, 57, 43, 0.25);
            --shadow-glow-gold: 0 0 30px rgba(212, 168, 83, 0.2);
            --radius-sm: 8px;
            --radius-md: 14px;
            --radius-lg: 20px;
            --radius-xl: 28px;
            --transition-fast: 0.2s ease;
            --transition-smooth: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
            --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
            --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
            --font-display: 'Playfair Display', Georgia, serif;
            --modal-anim: 0.3s ease;
            --max-width: 1300px;
            --nav-height: 60px;
        }

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

        html {
            scroll-behavior: smooth;
            font-size: 16px;
        }

        body {
            background: var(--bg-deep);
            color: var(--text-primary);
            font-family: var(--font-sans);
            line-height: 1.7;
            -webkit-font-smoothing: antialiased;
            overflow-x: hidden;
            min-height: 100vh;
            position: relative;
        }

        body::before {
            content: '';
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            pointer-events: none;
            z-index: -1;
            background:
                radial-gradient(ellipse at 20% 15%, rgba(192, 57, 43, 0.05) 0%, transparent 55%),
                radial-gradient(ellipse at 75% 60%, rgba(74, 158, 181, 0.03) 0%, transparent 55%);
        }

        /* Scrollbar */
        ::-webkit-scrollbar {
            width: 6px;
        }
        ::-webkit-scrollbar-track {
            background: var(--bg-primary);
        }
        ::-webkit-scrollbar-thumb {
            background: var(--border-medium);
            border-radius: 3px;
        }

        /* Language toggle */
        .lang-switch {
            position: fixed;
            top: 16px;
            right: 20px;
            z-index: 2000;
            display: flex;
            gap: 4px;
            background: var(--bg-card);
            border-radius: 30px;
            padding: 4px;
            border: 1px solid var(--border-medium);
            backdrop-filter: blur(20px);
            -webkit-backdrop-filter: blur(20px);
            box-shadow: var(--shadow-card);
        }
        .lang-switch button {
            padding: 8px 16px;
            border-radius: 26px;
            border: none;
            cursor: pointer;
            font-family: var(--font-sans);
            font-size: 0.8rem;
            font-weight: 600;
            letter-spacing: 0.04em;
            background: transparent;
            color: var(--text-secondary);
            transition: var(--transition-fast);
        }
        .lang-switch button.active {
            background: var(--accent-red);
            color: #fff;
            box-shadow: 0 2px 15px rgba(192, 57, 43, 0.4);
        }
        .lang-switch button:hover:not(.active) {
            color: var(--text-primary);
            background: rgba(255, 255, 255, 0.05);
        }

        /* Nav */
        .main-nav {
            position: sticky;
            top: 0;
            background: rgba(8, 8, 15, 0.85);
            backdrop-filter: blur(25px);
            -webkit-backdrop-filter: blur(25px);
            border-bottom: 1px solid var(--border-subtle);
            z-index: 1000;
            display: flex;
            justify-content: center;
            flex-wrap: wrap;
            gap: 6px;
            padding: 12px 20px;
        }
        .main-nav a {
            text-decoration: none;
            color: var(--text-secondary);
            font-size: 0.85rem;
            font-weight: 500;
            padding: 8px 16px;
            border-radius: 25px;
            transition: var(--transition-fast);
            letter-spacing: 0.03em;
            border: 1px solid transparent;
        }
        .main-nav a:hover,
        .main-nav a.active {
            background: var(--bg-card);
            border-color: var(--border-medium);
            color: var(--text-primary);
        }
        .main-nav a.nav-accent {
            color: var(--accent-amber);
            border-color: rgba(212, 168, 83, 0.4);
        }

        .container {
            max-width: var(--max-width);
            margin: 0 auto;
            padding: 20px 28px 60px;
        }

        /* Hero */
        .hero {
            text-align: center;
            padding: 50px 20px 30px;
        }
        .hero-badge {
            display: inline-block;
            background: rgba(192, 57, 43, 0.12);
            border: 1px solid rgba(192, 57, 43, 0.4);
            color: var(--accent-crimson);
            font-family: var(--font-mono);
            font-size: 0.7rem;
            letter-spacing: 0.1em;
            padding: 6px 18px;
            border-radius: 30px;
            margin-bottom: 18px;
        }
        h1 {
            font-family: var(--font-display);
            font-size: clamp(2.2rem, 5vw, 3.8rem);
            font-weight: 900;
            line-height: 1.2;
            letter-spacing: -0.02em;
            background: linear-gradient(180deg, #fff 20%, #c0b8a0 70%, #8a7a5a 100%);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
            margin-bottom: 15px;
        }
        .hero-subtitle {
            font-size: 1.1rem;
            color: var(--text-secondary);
            max-width: 700px;
            margin: 0 auto;
            font-weight: 400;
        }

        /* Section headers */
        .section-title {
            display: flex;
            align-items: center;
            gap: 12px;
            margin: 40px 0 20px;
        }
        .section-title .icon {
            font-size: 1.6rem;
            background: var(--bg-elevated);
            border-radius: 12px;
            width: 44px;
            height: 44px;
            display: flex;
            align-items: center;
            justify-content: center;
            border: 1px solid var(--border-medium);
        }
        .section-title h2 {
            font-family: var(--font-display);
            font-size: 1.8rem;
            font-weight: 700;
            letter-spacing: -0.01em;
        }
        .section-title .tag {
            font-family: var(--font-mono);
            font-size: 0.7rem;
            background: var(--bg-elevated);
            padding: 4px 12px;
            border-radius: 14px;
            color: var(--text-tertiary);
        }

        /* Cards grid */
        .cards-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
            gap: 20px;
            margin-bottom: 40px;
        }
        .card {
            background: var(--bg-card);
            border: 1px solid var(--border-subtle);
            border-radius: var(--radius-lg);
            padding: 24px;
            transition: var(--transition-smooth);
            position: relative;
            cursor: default;
            overflow: hidden;
        }
        .card:hover {
            background: var(--bg-card-hover);
            border-color: var(--border-medium);
            box-shadow: var(--shadow-card);
            transform: translateY(-3px);
        }
        .card .badge {
            display: inline-block;
            font-family: var(--font-mono);
            font-size: 0.6rem;
            letter-spacing: 0.08em;
            padding: 3px 10px;
            border-radius: 12px;
            margin-bottom: 10px;
            font-weight: 600;
            text-transform: uppercase;
        }
        .badge-red {
            background: rgba(192, 57, 43, 0.2);
            color: var(--accent-crimson);
            border: 1px solid rgba(192, 57, 43, 0.3);
        }
        .badge-gold {
            background: rgba(212, 168, 83, 0.2);
            color: var(--accent-gold);
            border: 1px solid rgba(212, 168, 83, 0.3);
        }
        .badge-teal {
            background: rgba(46, 204, 172, 0.2);
            color: var(--accent-teal);
            border: 1px solid rgba(46, 204, 172, 0.3);
        }
        .badge-cool {
            background: rgba(74, 158, 181, 0.2);
            color: var(--accent-cool);
            border: 1px solid rgba(74, 158, 181, 0.3);
        }
        .badge-purple {
            background: rgba(142, 68, 173, 0.2);
            color: var(--accent-purple);
            border: 1px solid rgba(142, 68, 173, 0.3);
        }
        .card h3 {
            font-size: 1.2rem;
            font-weight: 700;
            margin-bottom: 6px;
        }
        .card .algo-ref {
            font-family: var(--font-mono);
            font-size: 0.65rem;
            color: var(--text-tertiary);
            margin-bottom: 8px;
        }
        .card p {
            font-size: 0.88rem;
            color: var(--text-secondary);
            line-height: 1.6;
        }
        .card .chip-row {
            display: flex;
            flex-wrap: wrap;
            gap: 8px;
            margin-top: 14px;
        }
        .chip {
            font-family: var(--font-mono);
            font-size: 0.68rem;
            background: var(--bg-elevated);
            padding: 5px 10px;
            border-radius: 14px;
            color: var(--text-tertiary);
            letter-spacing: 0.03em;
        }
        .chip.highlight {
            background: rgba(240, 192, 96, 0.12);
            color: var(--accent-amber);
            border: 1px solid rgba(240, 192, 96, 0.3);
            font-weight: 600;
        }
        .card .link-arrow {
            display: inline-flex;
            align-items: center;
            gap: 6px;
            margin-top: 12px;
            color: var(--accent-cool);
            text-decoration: none;
            font-weight: 600;
            font-size: 0.85rem;
            transition: var(--transition-fast);
        }
        .card .link-arrow:hover {
            gap: 12px;
            color: var(--accent-teal);
        }

        /* Accordion */
        .accordion {
            margin-bottom: 12px;
            border: 1px solid var(--border-subtle);
            border-radius: var(--radius-md);
            overflow: hidden;
        }
        .accordion-header {
            background: var(--bg-card);
            padding: 16px 20px;
            cursor: pointer;
            font-weight: 600;
            display: flex;
            justify-content: space-between;
            align-items: center;
            transition: var(--transition-fast);
            border-bottom: 1px solid transparent;
        }
        .accordion-header:hover {
            background: var(--bg-card-hover);
        }
        .accordion-header.active {
            border-bottom: 1px solid var(--border-medium);
        }
        .accordion-content {
            max-height: 0;
            overflow: hidden;
            transition: max-height 0.4s ease;
            background: var(--bg-primary);
            padding: 0 20px;
        }
        .accordion-content.open {
            max-height: 500px;
            padding: 16px 20px;
        }

        /* Table */
        .table-wrap {
            overflow-x: auto;
            margin: 30px 0;
            border-radius: var(--radius-lg);
            border: 1px solid var(--border-subtle);
        }
        table {
            width: 100%;
            border-collapse: collapse;
            font-size: 0.82rem;
            min-width: 700px;
        }
        th {
            background: var(--bg-elevated);
            padding: 14px 16px;
            text-align: left;
            font-weight: 600;
            letter-spacing: 0.04em;
            color: var(--text-primary);
            font-size: 0.7rem;
            text-transform: uppercase;
            border-bottom: 2px solid var(--border-medium);
        }
        td {
            padding: 12px 16px;
            border-bottom: 1px solid var(--border-subtle);
            color: var(--text-secondary);
        }
        tr:hover td {
            background: rgba(255, 255, 255, 0.015);
            color: var(--text-primary);
        }

        /* Modal */
        .modal-overlay {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(0,0,0,0.8);
            display: flex;
            align-items: center;
            justify-content: center;
            z-index: 5000;
            visibility: hidden;
            opacity: 0;
            transition: opacity var(--modal-anim), visibility var(--modal-anim);
        }
        .modal-overlay.active {
            visibility: visible;
            opacity: 1;
        }
        .modal-box {
            background: var(--bg-modal);
            border: 1px solid var(--border-medium);
            border-radius: var(--radius-xl);
            max-width: 650px;
            width: 90%;
            padding: 30px;
            position: relative;
            max-height: 85vh;
            overflow-y: auto;
            box-shadow: 0 20px 60px rgba(0,0,0,0.8);
            transform: translateY(20px);
            transition: transform var(--modal-anim);
        }
        .modal-overlay.active .modal-box {
            transform: translateY(0);
        }
        .modal-close {
            position: absolute;
            top: 14px;
            right: 20px;
            background: none;
            border: none;
            color: var(--text-tertiary);
            font-size: 1.5rem;
            cursor: pointer;
            transition: color 0.2s;
        }
        .modal-close:hover {
            color: var(--accent-crimson);
        }

        /* Tooltips */
        [data-tooltip] {
            position: relative;
            border-bottom: 1px dotted var(--accent-amber);
            cursor: help;
        }
        [data-tooltip]:hover::after {
            content: attr(data-tooltip);
            position: absolute;
            bottom: 130%;
            left: 50%;
            transform: translateX(-50%);
            background: var(--bg-elevated);
            color: var(--text-primary);
            padding: 6px 12px;
            border-radius: 6px;
            font-size: 0.75rem;
            white-space: nowrap;
            border: 1px solid var(--border-medium);
            pointer-events: none;
            z-index: 10;
        }

        /* References */
        .references {
            margin-top: 40px;
            font-size: 0.8rem;
            color: var(--text-tertiary);
            line-height: 1.8;
        }
        .references a {
            color: var(--accent-cool);
            text-decoration: underline;
        }

        /* Language display control */
        body[data-lang='es'] .lang-en,
        body[data-lang='en'] .lang-es {
            display: none;
        }

        @media (max-width: 768px) {
            .cards-grid {
                grid-template-columns: 1fr;
            }
            .main-nav {
                gap: 2px;
                justify-content: flex-start;
                overflow-x: auto;
                flex-wrap: nowrap;
            }
            .main-nav a {
                padding: 6px 12px;
                font-size: 0.7rem;
                white-space: nowrap;
            }
        }