/* ========== 全局重置 & 与首页完全统一的风格 ========== */
        *{margin:0;padding:0;box-sizing:border-box;}
        body {
            font-family: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
            background: #f9fafc;
            color: #0b1e33;
            line-height: 1.5;
            scroll-behavior: smooth;
        }
        .container { max-width: 1280px; margin: 0 auto; padding: 0 24px; }
        
        /* 头部 — 毛玻璃现代 (同首页) */
        header {
            background: rgba(255,255,255,0.92);
            backdrop-filter: blur(12px);
            box-shadow: 0 4px 20px rgba(0,0,0,0.02);
            position: sticky;
            top: 0;
            z-index: 50;
            border-bottom: 1px solid #eef2f6;
        }
        .header-flex {
            display: flex;
            align-items: center;
            justify-content: space-between;
            flex-wrap: wrap;
            padding: 14px 0;
        }
        .logo-area h1 {
            font-size: 1.9rem;
            font-weight: 750;
            background: linear-gradient(145deg, #0f2b4b, #2563eb);
            background-clip: text;
            -webkit-background-clip: text;
            color: transparent;
            letter-spacing: -0.5px;
        }
        .logo-area p {
            font-size: 0.75rem;
            color: #54708f;
            margin-top: 4px;
            font-weight: 400;
            letter-spacing: 0.3px;
        }
        .nav-links {
            display: flex;
            gap: 1.4rem;
            align-items: center;
            flex-wrap: wrap;
        }
        .nav-links a {
            text-decoration: none;
            font-weight: 530;
            color: #1e2f44;
            transition: color 0.15s;
            font-size: 0.95rem;
        }
        .nav-links a:hover, .nav-links a.active { color: #2563eb; }

        /* 教程特色区域 */
        .mission-hero {
            text-align: center;
            margin: 48px 0 32px;
        }
        .mission-hero h1 {
            font-size: 3.2rem;
            font-weight: 800;
            background: linear-gradient(135deg, #0b1e2e, #1e4bd2);
            background-clip: text;
            -webkit-background-clip: text;
            color: transparent;
            letter-spacing: -0.02em;
        }
        .sub-mission {
            font-size: 1.2rem;
            color: #2c405c;
            margin-top: 8px;
        }
        .progress-summary {
            background: white;
            border-radius: 60px;
            padding: 16px 32px;
            display: inline-block;
            margin-top: 24px;
            box-shadow: 0 8px 18px rgba(0,0,0,0.02);
            border: 1px solid #d4e2f5;
        }
        .progress-text { font-weight: 700; font-size: 1.2rem; }

        /* 任务卡片 (三步图文结构) */
        .tasks-grid {
            display: flex;
            flex-direction: column;
            gap: 32px;
            margin: 40px 0 50px;
        }
        .task-card {
            background: white;
            border-radius: 48px;
            padding: 36px 40px;
            box-shadow: 0 25px 40px -16px rgba(0,35,70,0.06);
            border: 1px solid #eaf0fa;
            transition: all 0.2s;
        }
        .task-card.completed {
            border-left: 12px solid #10b981;
            background: #fbfeff;
        }
        .task-header {
            display: flex;
            align-items: center;
            gap: 20px;
            margin-bottom: 24px;
        }
        .task-number {
            background: #1e3b63;
            color: white;
            width: 56px;
            height: 56px;
            border-radius: 30px;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.8rem;
            font-weight: 800;
        }
        .task-title { font-size: 2rem; font-weight: 750; flex: 1; }
        .complete-btn {
            background: #eef4ff;
            border: none;
            padding: 12px 28px;
            border-radius: 60px;
            font-weight: 700;
            font-size: 1rem;
            color: #1e3b63;
            cursor: pointer;
            transition: all 0.15s;
            border: 1.5px solid transparent;
        }
        .complete-btn:hover { background: #2563eb; color: white; }
        .complete-btn.done { background: #10b981; color: white; border-color: #10b981; }
        .task-content {
            display: grid;
            grid-template-columns: 1.2fr 0.8fr;
            gap: 30px;
        }
        .task-steps { list-style: none; }
        .task-steps li {
            margin-bottom: 18px;
            display: flex;
            align-items: flex-start;
            gap: 14px;
            font-size: 1.05rem;
        }
        .step-check { color: #10b981; font-weight: bold; font-size: 1.4rem; }
        .task-visual {
            background: #f2f8ff;
            border-radius: 36px;
            padding: 20px;
            display: flex;
            flex-direction: column;
            justify-content: center;
        }
        .code-mini {
            background: #0a1c2f;
            color: #bdd3ff;
            padding: 12px 16px;
            border-radius: 24px;
            font-family: 'SF Mono', monospace;
            font-size: 0.9rem;
            margin-top: 16px;
        }

        /* 常见错误 & TUN引流卡片 (融合创意) */
        .extra-guide-row {
            display: flex;
            flex-wrap: wrap;
            gap: 30px;
            margin: 40px 0 60px;
        }
        .error-box {
            flex: 1.5;
            background: #fff7e6;
            border-radius: 32px;
            padding: 32px;
            border: 1px solid #ffddb0;
        }
        .error-box h3 { font-size: 1.8rem; margin-bottom: 20px; display: flex; gap: 10px; }
        .error-list li { margin-bottom: 16px; color: #5f3e1c; }
        .tun-teaser {
            flex: 1;
            background: linear-gradient(135deg, #1e3b63, #2563eb);
            border-radius: 32px;
            padding: 32px;
            color: white;
            display: flex;
            flex-direction: column;
        }
        .tun-teaser h3 { font-size: 1.8rem; margin-bottom: 16px; }
        .tun-teaser p { opacity: 0.9; margin-bottom: 24px; }
        .tun-link {
            background: white;
            color: #1e3b63;
            padding: 14px 20px;
            border-radius: 60px;
            font-weight: 700;
            text-decoration: none;
            text-align: center;
            margin-top: auto;
        }

        /* CTA 下载号召 */
        .cta-tutorial {
            background: #0f2b4b;
            border-radius: 60px;
            padding: 52px 48px;
            margin: 60px 0 40px;
            color: white;
            text-align: center;
        }
        .cta-tutorial h3 { font-size: 2.5rem; font-weight: 700; margin-bottom: 20px; }
        .btn-download-large {
            background: white;
            color: #0f2b4b;
            padding: 18px 54px;
            border-radius: 60px;
            font-weight: 700;
            font-size: 1.3rem;
            text-decoration: none;
            display: inline-block;
            margin-top: 20px;
            transition: 0.2s;
        }
        .btn-download-large:hover { background: #e0edff; transform: scale(1.02); }

        footer {
            background: #0b1a2a;
            color: #b0c7de;
            padding: 40px 0 24px;
            margin-top: 20px;
            border-top: 1px solid #1e3347;
        }
        .footer-grid { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 32px; }
        .footer-copyright {
            text-align: center;
            padding-top: 32px;
            font-size: 0.85rem;
            border-top: 1px solid #1e3347;
            margin-top: 24px;
        }

        @media (max-width: 700px) {
            .task-content { grid-template-columns: 1fr; }
            .mission-hero h1 { font-size: 2.2rem; }
            .task-card { padding: 24px; }
            .header-flex { flex-direction: column; gap: 12px; }
            .nav-links { justify-content: center; }
            .extra-guide-row { flex-direction: column; }
        }