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

    body {
        font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
        line-height: 1.6;
        color: #333;
        background-color: #fff;
    }

    .hed19-header {
        background: #fff;
        box-shadow: 0 2px 10px rgba(0,0,0,0.1);
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        z-index: 1000;
    }

    .hed19-nav {
        max-width: 1200px;
        margin: 0 auto;
        display: flex;
        align-items: center;
        justify-content: space-between;
        padding: 0 20px;
        height: 70px;
    }

    .hed19-logo img {
        height: 40px;
        width: auto;
    }

    .hed19-menu-toggle {
        display: none;
        flex-direction: column;
        background: none;
        border: none;
        cursor: pointer;
        padding: 5px;
    }

    .hed19-menu-toggle span {
        width: 25px;
        height: 3px;
        background: #333;
        margin: 3px 0;
        transition: 0.3s;
    }

    .hed19-nav-menu {
        display: flex;
        list-style: none;
        gap: 30px;
    }

    .hed19-nav-menu a {
        text-decoration: none;
        color: #333;
        font-weight: 500;
        transition: color 0.3s;
    }

    .hed19-nav-menu a:hover,
    .hed19-nav-menu a.active {
        color: #4285f4;
    }

    .hed19-nav-overlay {
        display: none;
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background: rgba(0,0,0,0.5);
        z-index: 999;
    }

    .hed19-tutorial-header {
        background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
        color: white;
        padding: 120px 0 80px;
        text-align: center;
    }

    .hed19-tutorial-header .container {
        max-width: 1200px;
        margin: 0 auto;
        padding: 0 20px;
    }

    .hed19-breadcrumb {
        display: flex;
        align-items: center;
        justify-content: center;
        gap: 10px;
        margin-bottom: 30px;
        font-size: 14px;
        opacity: 0.9;
    }

    .hed19-breadcrumb a {
        color: white;
        text-decoration: none;
    }

    .hed19-breadcrumb span {
        opacity: 0.7;
    }

    .hed19-tutorial-title {
        font-size: 3rem;
        font-weight: 700;
        margin-bottom: 20px;
    }

    .hed19-tutorial-subtitle {
        font-size: 1.2rem;
        opacity: 0.9;
        max-width: 600px;
        margin: 0 auto;
    }

    .hed19-tutorial-nav {
        background: #f8f9fa;
        padding: 40px 0;
        border-bottom: 1px solid #e9ecef;
    }

    .hed19-tutorial-nav .container {
        max-width: 1200px;
        margin: 0 auto;
        padding: 0 20px;
    }

    .hed19-tutorial-categories {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
        gap: 20px;
    }

    .hed19-category-card {
        background: white;
        border-radius: 12px;
        padding: 30px;
        text-align: center;
        box-shadow: 0 4px 20px rgba(0,0,0,0.1);
        transition: transform 0.3s, box-shadow 0.3s;
        cursor: pointer;
        border: 2px solid transparent;
    }

    .hed19-category-card:hover {
        transform: translateY(-5px);
        box-shadow: 0 8px 30px rgba(0,0,0,0.15);
        border-color: #4285f4;
    }

    .hed19-category-icon {
        font-size: 3rem;
        margin-bottom: 20px;
        display: block;
    }

    .hed19-category-title {
        font-size: 1.3rem;
        font-weight: 600;
        margin-bottom: 10px;
        color: #333;
    }

    .hed19-category-desc {
        color: #666;
        font-size: 0.9rem;
        line-height: 1.5;
    }

    .hed19-tutorial-content {
        padding: 60px 0;
    }

    .hed19-tutorial-content .container {
        max-width: 1200px;
        margin: 0 auto;
        padding: 0 20px;
    }

    .hed19-content-grid {
        display: grid;
        grid-template-columns: 300px 1fr;
        gap: 40px;
        align-items: start;
    }

    .hed19-sidebar {
        position: sticky;
        top: 120px;
    }

    .hed19-sidebar-menu {
        background: white;
        border-radius: 12px;
        box-shadow: 0 4px 20px rgba(0,0,0,0.1);
        overflow: hidden;
    }

    .hed19-sidebar-title {
        background: #4285f4;
        color: white;
        padding: 20px;
        font-weight: 600;
        font-size: 1.1rem;
    }

    .hed19-sidebar-list {
        list-style: none;
    }

    .hed19-sidebar-item {
        border-bottom: 1px solid #f0f0f0;
    }

    .hed19-sidebar-item:last-child {
        border-bottom: none;
    }

    .hed19-sidebar-link {
        display: block;
        padding: 15px 20px;
        color: #333;
        text-decoration: none;
        transition: all 0.3s;
        font-size: 0.9rem;
    }

    .hed19-sidebar-link:hover,
    .hed19-sidebar-link.active {
        background: #f8f9ff;
        color: #4285f4;
        padding-left: 30px;
    }

    .hed19-main-content {
        background: white;
        border-radius: 12px;
        box-shadow: 0 4px 20px rgba(0,0,0,0.1);
        overflow: hidden;
    }

    .hed19-tutorial-section {
        padding: 40px;
        border-bottom: 1px solid #f0f0f0;
    }

    .hed19-tutorial-section:last-child {
        border-bottom: none;
    }

    .hed19-section-title {
        font-size: 1.8rem;
        font-weight: 600;
        margin-bottom: 20px;
        color: #333;
        display: flex;
        align-items: center;
        gap: 15px;
    }

    .hed19-section-icon {
        font-size: 2rem;
    }

    .hed19-section-content {
        color: #666;
        line-height: 1.8;
        margin-bottom: 30px;
    }

    .hed19-steps-grid {
        display: grid;
        gap: 20px;
    }

    .hed19-step-item {
        display: flex;
        gap: 20px;
        padding: 25px;
        background: #f8f9fa;
        border-radius: 12px;
        border-left: 4px solid #4285f4;
    }

    .hed19-step-number {
        background: #4285f4;
        color: white;
        width: 40px;
        height: 40px;
        border-radius: 50%;
        display: flex;
        align-items: center;
        justify-content: center;
        font-weight: 600;
        flex-shrink: 0;
    }

    .hed19-step-content h4 {
        font-size: 1.1rem;
        font-weight: 600;
        margin-bottom: 8px;
        color: #333;
    }

    .hed19-step-content p {
        color: #666;
        line-height: 1.6;
    }

    .hed19-feature-grid {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
        gap: 25px;
        margin-top: 30px;
    }

    .hed19-feature-item {
        background: white;
        border: 1px solid #e9ecef;
        border-radius: 12px;
        padding: 25px;
        transition: all 0.3s;
    }

    .hed19-feature-item:hover {
        box-shadow: 0 8px 25px rgba(0,0,0,0.1);
        transform: translateY(-2px);
    }

    .hed19-feature-icon {
        font-size: 2.5rem;
        margin-bottom: 15px;
        display: block;
    }

    .hed19-feature-title {
        font-size: 1.2rem;
        font-weight: 600;
        margin-bottom: 10px;
        color: #333;
    }

    .hed19-feature-desc {
        color: #666;
        line-height: 1.6;
    }

    .hed19-tutorial-image {
        width: 100%;
        height: 300px;
        object-fit: cover;
        border-radius: 12px;
        margin: 30px 0;
        box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    }

    .hed19-tips-box {
        background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
        color: white;
        padding: 30px;
        border-radius: 12px;
        margin: 30px 0;
    }

    .hed19-tips-title {
        font-size: 1.3rem;
        font-weight: 600;
        margin-bottom: 15px;
        display: flex;
        align-items: center;
        gap: 10px;
    }

    .hed19-tips-content {
        line-height: 1.7;
        opacity: 0.95;
    }

    .hed19-footer {
        background: #2c3e50;
        color: white;
        padding: 60px 0 30px;
    }

    .hed19-footer .container {
        max-width: 1200px;
        margin: 0 auto;
        padding: 0 20px;
    }

    .hed19-footer-grid {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
        gap: 40px;
        margin-bottom: 40px;
    }

    .hed19-footer-section h3 {
        font-size: 1.2rem;
        margin-bottom: 20px;
        color: #ecf0f1;
    }

    .hed19-footer-links {
        list-style: none;
    }

    .hed19-footer-links li {
        margin-bottom: 10px;
    }

    .hed19-footer-links a {
        color: #bdc3c7;
        text-decoration: none;
        transition: color 0.3s;
    }

    .hed19-footer-links a:hover {
        color: #3498db;
    }

    .hed19-footer-bottom {
        border-top: 1px solid #34495e;
        padding-top: 30px;
        text-align: center;
        color: #95a5a6;
    }

    @media (max-width: 768px) {
        .hed19-menu-toggle {
            display: flex;
        }

        .hed19-nav-menu {
            display: none;
            position: fixed;
            top: 70px;
            left: 0;
            right: 0;
            background: white;
            flex-direction: column;
            padding: 20px;
            box-shadow: 0 4px 20px rgba(0,0,0,0.1);
        }

        .hed19-nav-menu.active {
            display: flex;
        }

        .hed19-nav-overlay.active {
            display: block;
        }

        .hed19-tutorial-title {
            font-size: 2rem;
        }

        .hed19-tutorial-categories {
            grid-template-columns: 1fr;
        }

        .hed19-content-grid {
            grid-template-columns: 1fr;
            gap: 30px;
        }

        .hed19-sidebar {
            position: static;
            order: 2;
        }

        .hed19-main-content {
            order: 1;
        }

        .hed19-tutorial-section {
            padding: 30px 20px;
        }

        .hed19-section-title {
            font-size: 1.5rem;
        }

        .hed19-feature-grid {
            grid-template-columns: 1fr;
        }

        .hed19-step-item {
            flex-direction: column;
            text-align: center;
        }
    }

    @media (max-width: 480px) {
        .hed19-nav {
            padding: 0 15px;
        }

        .hed19-tutorial-header {
            padding: 100px 0 60px;
        }

        .hed19-tutorial-title {
            font-size: 1.8rem;
        }

        .hed19-category-card {
            padding: 20px;
        }

        .hed19-tutorial-section {
            padding: 20px 15px;
        }
    }