/* ==================== CSS Reset & Variables ==================== */
        *, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

        :root {
            --primary: #F7931A;
            --primary-dark: #E8850F;
            --primary-light: #FFF3E0;
            --accent: #4A90D9;
            --accent-dark: #2E6DB4;
            --dark: #1A1A2E;
            --dark-2: #16213E;
            --gray-900: #212529;
            --gray-700: #495057;
            --gray-500: #6c757d;
            --gray-300: #dee2e6;
            --gray-100: #f8f9fa;
            --white: #ffffff;
            --success: #28a745;
            --warning: #ffc107;
            --danger: #dc3545;
            --gradient-1: linear-gradient(135deg, #1A1A2E 0%, #16213E 50%, #0F3460 100%);
            --gradient-2: linear-gradient(135deg, #F7931A 0%, #F2A900 100%);
            --shadow-sm: 0 2px 8px rgba(0,0,0,0.06);
            --shadow-md: 0 4px 20px rgba(0,0,0,0.1);
            --shadow-lg: 0 10px 40px rgba(0,0,0,0.15);
            --radius: 16px;
            --radius-sm: 10px;
            --max-w: 1100px;
        }

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

        body {
            font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
            color: var(--gray-900);
            background: var(--gray-100);
            line-height: 1.8;
            -webkit-font-smoothing: antialiased;
        }

        a { color: var(--accent); text-decoration: none; transition: color .2s; }
        a:hover { color: var(--accent-dark); }
        img { max-width: 100%; display: block; }

        /* ==================== Navigation ==================== */
        .top-nav {
            background: var(--white);
            border-bottom: 1px solid var(--gray-300);
            position: sticky;
            top: 0;
            z-index: 1000;
            backdrop-filter: blur(12px);
            background: rgba(255,255,255,0.92);
        }
        .nav-inner {
            max-width: var(--max-w);
            margin: 0 auto;
            padding: 0 20px;
            display: flex;
            align-items: center;
            justify-content: space-between;
            height: 60px;
        }
        .nav-logo {
            display: flex;
            align-items: center;
            gap: 10px;
            font-weight: 700;
            font-size: 1.15rem;
            color: var(--dark);
        }
        .nav-logo .btc-icon {
            width: 34px; height: 34px;
            background: var(--gradient-2);
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            color: var(--white);
            font-weight: 900;
            font-size: 1.1rem;
        }
        .nav-links { display: flex; gap: 28px; list-style: none; }
        .nav-links a {
            color: var(--gray-700);
            font-size: .9rem;
            font-weight: 500;
            transition: color .2s;
        }
        .nav-links a:hover { color: var(--primary); }
        .mobile-toggle { display: none; background: none; border: none; font-size: 1.5rem; cursor: pointer; }

        /* ==================== Breadcrumb ==================== */
        .breadcrumb-bar {
            max-width: var(--max-w);
            margin: 0 auto;
            padding: 14px 20px 0;
            font-size: .82rem;
            color: var(--gray-500);
        }
        .breadcrumb-bar a { color: var(--gray-500); }
        .breadcrumb-bar a:hover { color: var(--primary); }
        .breadcrumb-bar span { margin: 0 6px; }

        /* ==================== Hero ==================== */
        .hero {
            background: var(--gradient-1);
            color: var(--white);
            padding: 64px 20px 56px;
            margin-top: 0;
            position: relative;
            overflow: hidden;
        }
        .hero::before {
            content: '₿';
            position: absolute;
            font-size: 320px;
            right: -30px;
            top: -40px;
            opacity: 0.04;
            font-weight: 900;
        }
        .hero-inner {
            max-width: var(--max-w);
            margin: 0 auto;
            position: relative;
            z-index: 1;
        }
        .hero-badge {
            display: inline-block;
            background: rgba(247,147,26,0.2);
            color: var(--primary);
            padding: 5px 16px;
            border-radius: 50px;
            font-size: .8rem;
            font-weight: 500;
            margin-bottom: 20px;
            border: 1px solid rgba(247,147,26,0.3);
        }
        .hero h1 {
            font-size: 2.4rem;
            font-weight: 900;
            line-height: 1.3;
            margin-bottom: 16px;
        }
        .hero h1 em { color: var(--primary); font-style: normal; }
        .hero-desc {
            font-size: 1.05rem;
            color: rgba(255,255,255,0.75);
            max-width: 640px;
            margin-bottom: 28px;
        }
        .hero-stats {
            display: flex;
            gap: 32px;
            flex-wrap: wrap;
        }
        .hero-stat {
            text-align: left;
        }
        .hero-stat strong {
            display: block;
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--primary);
        }
        .hero-stat span {
            font-size: .8rem;
            color: rgba(255,255,255,0.55);
        }

        /* ==================== TOC (Table of Contents) ==================== */
        .toc-section {
            max-width: var(--max-w);
            margin: -28px auto 0;
            padding: 0 20px;
            position: relative;
            z-index: 2;
        }
        .toc-card {
            background: var(--white);
            border-radius: var(--radius);
            box-shadow: var(--shadow-lg);
            padding: 28px 32px;
        }
        .toc-title {
            font-size: .85rem;
            font-weight: 700;
            color: var(--gray-500);
            text-transform: uppercase;
            letter-spacing: 1px;
            margin-bottom: 14px;
        }
        .toc-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
            gap: 10px;
        }
        .toc-grid a {
            display: flex;
            align-items: center;
            gap: 10px;
            padding: 10px 14px;
            border-radius: var(--radius-sm);
            color: var(--gray-700);
            font-size: .9rem;
            font-weight: 500;
            transition: all .2s;
        }
        .toc-grid a:hover {
            background: var(--primary-light);
            color: var(--primary-dark);
        }
        .toc-num {
            width: 26px; height: 26px;
            background: var(--primary-light);
            color: var(--primary);
            border-radius: 8px;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: .75rem;
            font-weight: 700;
            flex-shrink: 0;
        }

        /* ==================== Content Sections ==================== */
        .content-area {
            max-width: var(--max-w);
            margin: 40px auto;
            padding: 0 20px;
        }

        .section-block {
            background: var(--white);
            border-radius: var(--radius);
            box-shadow: var(--shadow-sm);
            padding: 40px 36px;
            margin-bottom: 28px;
        }

        .section-block h2 {
            font-size: 1.55rem;
            font-weight: 800;
            color: var(--dark);
            margin-bottom: 8px;
            display: flex;
            align-items: center;
            gap: 12px;
        }
        .section-block h2 .icon {
            width: 40px; height: 40px;
            background: var(--primary-light);
            border-radius: 12px;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.2rem;
            flex-shrink: 0;
        }
        .section-subtitle {
            color: var(--gray-500);
            font-size: .92rem;
            margin-bottom: 28px;
        }
        .section-block h3 {
            font-size: 1.15rem;
            font-weight: 700;
            margin: 28px 0 10px;
            color: var(--dark);
        }
        .section-block p {
            color: var(--gray-700);
            margin-bottom: 14px;
            font-size: .95rem;
        }

        /* ==================== Steps ==================== */
        .steps { counter-reset: step; }
        .step-item {
            display: flex;
            gap: 20px;
            padding: 24px 0;
            border-bottom: 1px solid var(--gray-300);
            position: relative;
        }
        .step-item:last-child { border-bottom: none; }
        .step-num {
            counter-increment: step;
            width: 50px; height: 50px;
            background: var(--gradient-2);
            border-radius: 14px;
            color: var(--white);
            font-weight: 800;
            font-size: 1.2rem;
            display: flex;
            align-items: center;
            justify-content: center;
            flex-shrink: 0;
        }
        .step-num::after { content: counter(step); }
        .step-body h3 { margin-top: 0 !important; font-size: 1.1rem; }
        .step-body p { margin-bottom: 8px; }

        .tip-box {
            background: #EFF6FF;
            border-left: 4px solid var(--accent);
            border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
            padding: 14px 18px;
            margin: 12px 0;
            font-size: .88rem;
            color: var(--accent-dark);
        }
        .warn-box {
            background: #FFF8E1;
            border-left: 4px solid var(--warning);
            border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
            padding: 14px 18px;
            margin: 12px 0;
            font-size: .88rem;
            color: #856404;
        }
        .danger-box {
            background: #FDEDED;
            border-left: 4px solid var(--danger);
            border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
            padding: 14px 18px;
            margin: 12px 0;
            font-size: .88rem;
            color: #842029;
        }

        /* ==================== Comparison Table ==================== */
        .compare-table {
            width: 100%;
            border-collapse: separate;
            border-spacing: 0;
            border-radius: var(--radius-sm);
            overflow: hidden;
            margin: 16px 0;
            font-size: .88rem;
        }
        .compare-table thead { background: var(--dark); color: var(--white); }
        .compare-table th {
            padding: 14px 16px;
            text-align: left;
            font-weight: 600;
        }
        .compare-table td {
            padding: 13px 16px;
            border-bottom: 1px solid var(--gray-300);
            color: var(--gray-700);
        }
        .compare-table tbody tr:hover { background: var(--primary-light); }
        .compare-table .tag-good {
            background: #d4edda;
            color: #155724;
            padding: 3px 10px;
            border-radius: 50px;
            font-size: .78rem;
            font-weight: 600;
        }
        .compare-table .tag-ok {
            background: #fff3cd;
            color: #856404;
            padding: 3px 10px;
            border-radius: 50px;
            font-size: .78rem;
            font-weight: 600;
        }

        /* ==================== FAQ Accordion ==================== */
        .faq-item {
            border: 1px solid var(--gray-300);
            border-radius: var(--radius-sm);
            margin-bottom: 12px;
            overflow: hidden;
            transition: box-shadow .2s;
        }
        .faq-item:hover { box-shadow: var(--shadow-sm); }
        .faq-question {
            width: 100%;
            background: none;
            border: none;
            padding: 18px 20px;
            display: flex;
            justify-content: space-between;
            align-items: center;
            cursor: pointer;
            font-size: .95rem;
            font-weight: 600;
            color: var(--dark);
            text-align: left;
            font-family: inherit;
        }
        .faq-question::after {
            content: '+';
            font-size: 1.3rem;
            font-weight: 300;
            color: var(--gray-500);
            transition: transform .3s;
            flex-shrink: 0;
            margin-left: 12px;
        }
        .faq-item.active .faq-question::after {
            content: '−';
        }
        .faq-answer {
            max-height: 0;
            overflow: hidden;
            transition: max-height .35s ease, padding .35s ease;
        }
        .faq-item.active .faq-answer {
            max-height: 500px;
        }
        .faq-answer-inner {
            padding: 0 20px 18px;
            font-size: .9rem;
            color: var(--gray-700);
            line-height: 1.8;
        }

        /* ==================== CTA Box ==================== */
        .cta-box {
            background: var(--gradient-1);
            border-radius: var(--radius);
            padding: 44px 40px;
            text-align: center;
            color: var(--white);
            margin-bottom: 28px;
        }
        .cta-box h2 { justify-content: center; color: var(--white); font-size: 1.6rem; margin-bottom: 12px; }
        .cta-box p { color: rgba(255,255,255,0.7); max-width: 500px; margin: 0 auto 24px; }
        .cta-btn {
            display: inline-block;
            background: var(--gradient-2);
            color: var(--white);
            padding: 14px 36px;
            border-radius: 50px;
            font-weight: 700;
            font-size: 1rem;
            transition: transform .2s, box-shadow .2s;
        }
        .cta-btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 8px 25px rgba(247,147,26,0.4);
            color: var(--white);
        }

        /* ==================== Footer ==================== */
        .site-footer {
            background: var(--dark);
            color: rgba(255,255,255,0.5);
            padding: 40px 20px;
            font-size: .82rem;
            text-align: center;
            line-height: 2;
        }
        .site-footer strong { color: rgba(255,255,255,0.8); }

        /* ==================== Responsive ==================== */
        @media (max-width: 768px) {
            .nav-links { display: none; }
            .mobile-toggle { display: block; }
            .nav-links.show {
                display: flex;
                flex-direction: column;
                position: absolute;
                top: 60px; left: 0; right: 0;
                background: var(--white);
                padding: 16px 20px;
                box-shadow: var(--shadow-md);
                gap: 14px;
            }
            .hero h1 { font-size: 1.7rem; }
            .hero { padding: 44px 20px 40px; }
            .hero-stats { gap: 20px; }
            .section-block { padding: 28px 20px; }
            .section-block h2 { font-size: 1.25rem; }
            .step-item { flex-direction: column; gap: 12px; }
            .compare-table { font-size: .78rem; }
            .compare-table th, .compare-table td { padding: 10px 8px; }
            .cta-box { padding: 32px 20px; }
            .toc-card { padding: 20px; }
        }

        /* ==================== Utility ==================== */
        .mt-0 { margin-top: 0 !important; }
        .highlight { color: var(--primary); font-weight: 700; }