:root {
      --main: #22d3ee;
      --accent: #fb923c;
      --bg: #0f172a;
      --text: #e2e8f0;
      --card-bg: #1e293b;
      --line: #334155;
      --radius: 8px;
      --shadow: 0 4px 16px rgba(0,0,0,0.3);
    }
    * { font-family: 'Inter', system-ui, sans-serif; }
    body {
      background-color: var(--bg);
      color: var(--text);
      line-height: 1.75;
      background-image: radial-gradient(circle, rgba(34,211,238,0.06) 1px, transparent 1px);
      background-size: 24px 24px;
    }
    .container { max-width: 1200px; }
    h1,h2,h3,.navbar-brand,.display-5 {
      font-family: 'Inter', 'Comic Sans MS', 'Chalkboard SE', 'Segoe Script', cursive, sans-serif;
      font-weight: 800;
      letter-spacing: 0.01em;
    }
    a { text-decoration: none; color: var(--main); }
    a:hover { color: var(--accent); }

    /* navbar */
    .navbar {
      background: rgba(15,23,42,0.85) !important;
      backdrop-filter: blur(10px);
      border-bottom: 1px solid var(--line);
      padding: 12px 0;
    }
    .navbar-brand {
      font-size: 1.8rem;
      font-weight: 900;
      color: var(--text) !important;
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .navbar-brand i { color: var(--accent); font-size: 2rem; }
    .nav-link {
      color: var(--text) !important;
      font-weight: 500;
      margin: 0 8px;
      transition: color 0.2s;
    }
    .nav-link:hover { color: var(--main) !important; }
    .btn-outline-main {
      border: 1px solid var(--main);
      color: var(--main);
      border-radius: var(--radius);
    }
    .btn-outline-main:hover { background: var(--main); color: #0f172a; }

    /* hero */
    .hero-section {
      background: linear-gradient(180deg, rgba(15,23,42,0.7) 0%, var(--bg) 100%), url('{随机图片}') center/cover fixed;
      padding: 7rem 0 5rem;
      border-bottom: 1px solid var(--line);
    }
    .hero-tag {
      display: inline-block;
      background: rgba(34,211,238,0.12);
      border: 1px solid var(--main);
      color: var(--main);
      border-radius: 30px;
      padding: 6px 18px;
      margin: 8px 8px 8px 0;
      font-size: 0.9rem;
      font-weight: 500;
      animation: fadeTag 0.8s ease backwards;
    }
    @keyframes fadeTag {
      0% { opacity: 0; transform: translateY(8px); }
      100% { opacity: 1; transform: translateY(0); }
    }
    .hero-title {
      font-size: 3.8rem;
      font-weight: 900;
      margin-top: 30px;
    }
    .hero-subtitle { font-size: 1.3rem; color: #cbd5e1; max-width: 650px; }

    /* section */
    .section-padding { padding: 5rem 0; }
    .section-title {
      font-size: 2.2rem;
      font-weight: 800;
      margin-bottom: 20px;
      position: relative;
      display: inline-block;
    }
    .section-title::after {
      content: '';
      display: block;
      width: 60px;
      height: 4px;
      background: var(--accent);
      border-radius: 4px;
      margin-top: 8px;
    }
    .divider { border-top: 1px solid var(--line); margin: 3rem 0; }

    /* card grid */
    .feature-card {
      background: var(--card-bg);
      border-radius: var(--radius);
      padding: 30px 24px;
      border: 1px solid var(--line);
      transition: transform 0.25s, border-color 0.25s, box-shadow 0.25s;
      box-shadow: 0 6px 12px rgba(0,0,0,0.2);
    }
    .feature-card:hover {
      transform: scale(1.02);
      border-color: var(--main);
      box-shadow: 0 8px 22px rgba(34,211,238,0.2);
    }
    .feature-icon {
      font-size: 2.6rem;
      color: var(--main);
      margin-bottom: 16px;
    }

    /* comparison table */
    .table {
      --bs-table-bg: transparent;
      --bs-table-border-color: var(--line);
      color: var(--text);
    }
    .table th, .table td {
      padding: 1rem;
      vertical-align: middle;
      border-color: var(--line);
    }
    .table thead th {
      background: #1e293b;
      color: var(--main);
      font-weight: 700;
      border-bottom: 2px solid var(--main);
    }
    .table-striped tbody tr:nth-of-type(odd) {
      background: rgba(30,41,59,0.4);
    }

    /* steps */
    .step-number {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      width: 36px;
      height: 36px;
      background: var(--accent);
      color: #0f172a;
      font-weight: 800;
      border-radius: 50%;
      margin-right: 12px;
      font-size: 1.2rem;
    }
    .step-item {
      background: rgba(30,41,59,0.5);
      border-radius: var(--radius);
      padding: 20px 24px;
      margin-bottom: 16px;
      border-left: 4px solid var(--main);
    }

    /* long article */
    .long-article {
      background: rgba(30,41,59,0.3);
      padding: 3rem 2rem;
      border-radius: 16px;
      border: 1px solid var(--line);
    }

    /* FAQ */
    .accordion-item {
      background-color: transparent;
      border: 1px solid var(--line);
      border-radius: var(--radius) !important;
      margin-bottom: 12px;
      overflow: hidden;
    }
    .accordion-button {
      background: var(--card-bg);
      color: var(--text);
      font-weight: 600;
      padding: 1.2rem 1.5rem;
    }
    .accordion-button:not(.collapsed) {
      background: #1e293b;
      color: var(--main);
    }
    .accordion-button:focus { box-shadow: none; }
    .accordion-body { background: rgba(30,41,59,0.5); }

    /* CTA */
    .cta-box {
      background: linear-gradient(120deg, rgba(34,211,238,0.1), rgba(251,146,60,0.1));
      border: 1px solid var(--main);
      border-radius: 16px;
      padding: 3rem 2rem;
    }
    .btn-main {
      background: var(--main);
      color: #0f172a;
      font-weight: 700;
      padding: 14px 36px;
      border-radius: 50px;
      border: none;
      transition: 0.2s;
    }
    .btn-main:hover {
      background: var(--accent);
      color: #0f172a;
      transform: translateY(-2px);
    }

    /* footer */
    footer {
      background: rgba(15,23,42,0.9);
      border-top: 1px solid var(--line);
      padding: 3rem 0;
    }
    .friend-links {
      background: #1e293b;
      padding: 2rem 1.5rem;
      border-radius: var(--radius);
      margin: 3rem 0;
      border: 1px dashed var(--line);
    }

    /* responsive */
    @media (max-width: 768px) {
      .hero-title { font-size: 2.5rem; }
      .hero-section { padding: 4rem 0; }
      .navbar-nav { margin-top: 10px; }
    }

/* --- 子页面追加 --- */
.about-hero {
            background: linear-gradient(135deg, rgba(34, 211, 238, 0.15), rgba(251, 146, 60, 0.1));
            border-bottom: 1px solid var(--line);
            padding: 80px 0 60px;
            text-align: center;
        }
.about-hero .hero-tag {
            display: inline-block;
            padding: 6px 18px;
            background: rgba(34, 211, 238, 0.15);
            border: 1px solid rgba(34, 211, 238, 0.3);
            border-radius: 30px;
            font-size: 14px;
            color: var(--main);
            margin-bottom: 20px;
            letter-spacing: 1px;
        }
.about-hero h1 {
            font-size: 2.6rem;
            font-weight: 800;
            color: var(--text);
            margin-bottom: 16px;
            line-height: 1.3;
        }
.about-hero h1 span {
            color: var(--main);
        }
.about-hero .hero-subtitle {
            max-width: 720px;
            margin: 0 auto;
            color: rgba(226, 232, 240, 0.8);
            font-size: 1.1rem;
            line-height: 1.8;
        }
.about-section {
            padding: 60px 0;
            border-bottom: 1px solid var(--line);
        }
.about-section:last-of-type {
            border-bottom: none;
        }
.about-section .section-title {
            font-size: 1.8rem;
            font-weight: 700;
            margin-bottom: 30px;
            position: relative;
            padding-bottom: 14px;
        }
.about-section .section-title::after {
            content: '';
            position: absolute;
            bottom: 0;
            left: 0;
            width: 60px;
            height: 3px;
            background: var(--main);
            border-radius: 3px;
        }
.about-section .section-title i {
            color: var(--main);
            margin-right: 10px;
        }
.about-text {
            color: rgba(226, 232, 240, 0.9);
            line-height: 1.9;
            font-size: 1rem;
        }
.about-text p {
            margin-bottom: 16px;
        }
.about-text strong {
            color: var(--main);
            font-weight: 600;
        }
.stat-grid {
            display: grid;
            grid-template-columns: repeat(4, 1fr);
            gap: 20px;
            margin-top: 30px;
        }
.stat-item {
            background: var(--card-bg);
            border: 1px solid var(--line);
            border-radius: var(--radius);
            padding: 24px 16px;
            text-align: center;
            transition: transform 0.3s, border-color 0.3s;
        }
.stat-item:hover {
            transform: translateY(-4px);
            border-color: var(--main);
        }
.stat-item .stat-num {
            font-size: 2.2rem;
            font-weight: 800;
            color: var(--main);
            display: block;
            margin-bottom: 6px;
        }
.stat-item .stat-label {
            font-size: 0.9rem;
            color: rgba(226, 232, 240, 0.7);
        }
.timeline {
            position: relative;
            padding-left: 30px;
            margin-top: 20px;
        }
.timeline::before {
            content: '';
            position: absolute;
            left: 8px;
            top: 0;
            bottom: 0;
            width: 2px;
            background: var(--line);
        }
.timeline-item {
            position: relative;
            margin-bottom: 30px;
        }
.timeline-item::before {
            content: '';
            position: absolute;
            left: -26px;
            top: 6px;
            width: 12px;
            height: 12px;
            border-radius: 50%;
            background: var(--main);
            box-shadow: 0 0 0 4px rgba(34, 211, 238, 0.2);
        }
.timeline-item .timeline-date {
            font-size: 0.85rem;
            color: var(--main);
            font-weight: 600;
            margin-bottom: 6px;
        }
.timeline-item .timeline-title {
            font-size: 1.1rem;
            font-weight: 600;
            color: var(--text);
            margin-bottom: 8px;
        }
.timeline-item .timeline-desc {
            font-size: 0.95rem;
            color: rgba(226, 232, 240, 0.8);
            line-height: 1.7;
        }
.feature-list {
            list-style: none;
            padding: 0;
            margin: 0;
        }
.feature-list li {
            padding: 12px 0;
            border-bottom: 1px solid rgba(51, 65, 85, 0.5);
            display: flex;
            align-items: flex-start;
            gap: 14px;
        }
.feature-list li:last-child {
            border-bottom: none;
        }
.feature-list li i {
            color: var(--main);
            font-size: 1.1rem;
            margin-top: 4px;
            width: 24px;
            text-align: center;
            flex-shrink: 0;
        }
.feature-list li .feature-text {
            color: rgba(226, 232, 240, 0.9);
            line-height: 1.7;
        }
.feature-list li .feature-text strong {
            color: var(--text);
            font-weight: 600;
        }
.values-grid {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 20px;
            margin-top: 20px;
        }
.value-card {
            background: var(--card-bg);
            border: 1px solid var(--line);
            border-radius: var(--radius);
            padding: 24px;
            transition: transform 0.3s, border-color 0.3s;
        }
.value-card:hover {
            transform: translateY(-4px);
            border-color: var(--accent);
        }
.value-card .value-icon {
            font-size: 2rem;
            color: var(--main);
            margin-bottom: 14px;
        }
.value-card h4 {
            font-size: 1.1rem;
            font-weight: 600;
            color: var(--text);
            margin-bottom: 10px;
        }
.value-card p {
            font-size: 0.9rem;
            color: rgba(226, 232, 240, 0.8);
            line-height: 1.7;
        }
.cta-box h3 {
            font-size: 1.6rem;
            font-weight: 700;
            color: var(--text);
            margin-bottom: 12px;
        }
.cta-box p {
            color: rgba(226, 232, 240, 0.8);
            margin-bottom: 20px;
            font-size: 1rem;
        }
.about-hero {
                padding: 60px 0 40px;
            }
.about-hero h1 {
                font-size: 1.8rem;
            }
.about-hero .hero-subtitle {
                font-size: 1rem;
            }
.stat-grid {
                grid-template-columns: repeat(2, 1fr);
            }
.values-grid {
                grid-template-columns: 1fr;
            }
.about-section .section-title {
                font-size: 1.4rem;
            }
.cta-box h3 {
                font-size: 1.3rem;
            }

/* --- 子页面追加 --- */
/* 隐私政策页面专属样式 */
        .privacy-section {
            background: var(--card-bg);
            border-radius: var(--radius);
            padding: 2rem;
            margin-bottom: 1.5rem;
            box-shadow: var(--shadow);
        }
.privacy-section h2 {
            color: var(--main);
            font-size: 1.5rem;
            font-weight: 700;
            margin-bottom: 1rem;
            display: flex;
            align-items: center;
            gap: 0.75rem;
        }
.privacy-section h2 i {
            color: var(--accent);
            font-size: 1.25rem;
        }
.privacy-section p, .privacy-section li {
            color: var(--text);
            line-height: 1.8;
            font-size: 0.95rem;
        }
.privacy-section ul {
            padding-left: 1.5rem;
            margin-top: 0.75rem;
        }
.privacy-section ul li {
            margin-bottom: 0.5rem;
        }
.privacy-section strong {
            color: var(--accent);
        }
.privacy-updated {
            background: rgba(34, 211, 238, 0.1);
            border-left: 4px solid var(--main);
            padding: 1rem 1.5rem;
            border-radius: 0 var(--radius) var(--radius) 0;
            margin-bottom: 2rem;
        }
.privacy-updated p {
            margin: 0;
            font-size: 0.9rem;
            color: var(--text);
        }
.privacy-updated i {
            color: var(--main);
            margin-right: 0.5rem;
        }
.contact-highlight {
            background: rgba(251, 146, 60, 0.1);
            border-left: 4px solid var(--accent);
            padding: 1rem 1.5rem;
            border-radius: 0 var(--radius) var(--radius) 0;
            margin-top: 1.5rem;
        }
.contact-highlight p {
            margin: 0;
            font-size: 0.95rem;
        }
.contact-highlight a {
            color: var(--main);
            font-weight: 600;
            text-decoration: none;
        }
.contact-highlight a:hover {
            color: var(--accent);
        }
.table-of-content {
            background: rgba(30, 41, 59, 0.6);
            border-radius: var(--radius);
            padding: 1.5rem 2rem;
            margin-bottom: 2rem;
            border: 1px solid var(--line);
        }
.table-of-content h3 {
            color: var(--main);
            font-size: 1.1rem;
            font-weight: 600;
            margin-bottom: 1rem;
        }
.table-of-content ul {
            list-style: none;
            padding: 0;
            margin: 0;
            columns: 2;
            column-gap: 2rem;
        }
.table-of-content li {
            margin-bottom: 0.5rem;
        }
.table-of-content a {
            color: var(--text);
            text-decoration: none;
            font-size: 0.9rem;
            display: flex;
            align-items: center;
            gap: 0.5rem;
            transition: color 0.2s ease;
        }
.table-of-content a:hover {
            color: var(--main);
        }
.table-of-content a i {
            font-size: 0.8rem;
            color: var(--accent);
        }
.table-of-content ul {
                columns: 1;
            }
.privacy-section {
                padding: 1.5rem;
            }
/* 覆盖 Bootstrap 卡片样式以防万一 */
        .card, .card-body, .card-title, .card-text {
            background: var(--card-bg);
            color: var(--text);
            border-color: var(--line);
        }
.list-group-item {
            background: var(--card-bg);
            color: var(--text);
            border-color: var(--line);
        }
.accordion-item, .accordion-button, .accordion-body {
            background: var(--card-bg);
            color: var(--text);
            border-color: var(--line);
        }

/* --- Bootstrap 组件配色适配(程序自动补,避免白底黑字) --- */
.accordion-header { background:transparent !important; }