* {
        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: sticky;
        top: 0;
        z-index: 1000;
    }

    .hed19-nav {
        max-width: 1200px;
        margin: 0 auto;
        padding: 0 20px;
        display: flex;
        align-items: center;
        justify-content: space-between;
        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;
        padding: 10px 0;
    }

    .hed19-nav-menu a:hover,
    .hed19-nav-menu a.active {
        color: #2196F3;
    }

    .hed19-nav-overlay {
        display: none;
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background: rgba(0,0,0,0.5);
        z-index: 999;
    }

    .hed19-support-header {
        background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
        color: white;
        padding: 60px 0;
        text-align: center;
    }

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

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

    .hed19-support-subtitle {
        font-size: 1.2rem;
        opacity: 0.9;
        margin-bottom: 40px;
    }

    .hed19-search-container {
        max-width: 600px;
        margin: 0 auto;
        position: relative;
    }

    .hed19-search-box {
        width: 100%;
        padding: 15px 50px 15px 20px;
        font-size: 1.1rem;
        border: none;
        border-radius: 50px;
        outline: none;
        box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    }

    .hed19-search-btn {
        position: absolute;
        right: 5px;
        top: 50%;
        transform: translateY(-50%);
        background: #2196F3;
        color: white;
        border: none;
        padding: 10px 20px;
        border-radius: 50px;
        cursor: pointer;
        font-weight: 600;
        transition: background 0.3s;
    }

    .hed19-search-btn:hover {
        background: #1976D2;
    }

    .hed19-main-content {
        max-width: 1200px;
        margin: 0 auto;
        padding: 80px 20px;
    }

    .hed19-help-categories {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
        gap: 30px;
        margin-bottom: 80px;
    }

    .hed19-category-card {
        background: white;
        border-radius: 15px;
        padding: 30px;
        box-shadow: 0 5px 20px rgba(0,0,0,0.1);
        transition: transform 0.3s, box-shadow 0.3s;
        cursor: pointer;
    }

    .hed19-category-card:hover {
        transform: translateY(-5px);
        box-shadow: 0 10px 30px rgba(0,0,0,0.15);
    }

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

    .hed19-category-title {
        font-size: 1.5rem;
        font-weight: 700;
        color: #333;
        margin-bottom: 15px;
    }

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

    .hed19-faq-section {
        margin-bottom: 80px;
    }

    .hed19-section-title {
        font-size: 2.5rem;
        font-weight: 700;
        text-align: center;
        margin-bottom: 50px;
        color: #333;
    }

    .hed19-faq-list {
        max-width: 800px;
        margin: 0 auto;
    }

    .hed19-faq-item {
        background: white;
        border-radius: 10px;
        margin-bottom: 20px;
        box-shadow: 0 2px 10px rgba(0,0,0,0.1);
        overflow: hidden;
    }

    .hed19-faq-question {
        padding: 25px 30px;
        background: #f8f9fa;
        cursor: pointer;
        display: flex;
        justify-content: space-between;
        align-items: center;
        font-weight: 600;
        font-size: 1.1rem;
        transition: background 0.3s;
    }

    .hed19-faq-question:hover {
        background: #e9ecef;
    }

    .hed19-faq-toggle {
        font-size: 1.5rem;
        color: #2196F3;
        transition: transform 0.3s;
    }

    .hed19-faq-item.active .hed19-faq-toggle {
        transform: rotate(45deg);
    }

    .hed19-faq-answer {
        padding: 0 30px;
        max-height: 0;
        overflow: hidden;
        transition: max-height 0.3s, padding 0.3s;
    }

    .hed19-faq-item.active .hed19-faq-answer {
        padding: 25px 30px;
        max-height: 500px;
    }

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

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

    .hed19-contact-title {
        font-size: 2.5rem;
        font-weight: 700;
        margin-bottom: 20px;
    }

    .hed19-contact-subtitle {
        font-size: 1.2rem;
        opacity: 0.9;
        margin-bottom: 50px;
    }

    .hed19-contact-methods {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
        gap: 30px;
        margin-bottom: 50px;
    }

    .hed19-contact-method {
        background: rgba(255,255,255,0.1);
        padding: 30px;
        border-radius: 15px;
        backdrop-filter: blur(10px);
    }

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

    .hed19-contact-method h3 {
        font-size: 1.3rem;
        margin-bottom: 10px;
    }

    .hed19-contact-method p {
        opacity: 0.9;
    }

    .hed19-install-guide {
        background: #f8f9fa;
        padding: 80px 0;
    }

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

    .hed19-guide-steps {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
        gap: 30px;
        margin-top: 50px;
    }

    .hed19-guide-step {
        background: white;
        padding: 30px;
        border-radius: 15px;
        text-align: center;
        box-shadow: 0 5px 20px rgba(0,0,0,0.1);
        position: relative;
    }

    .hed19-step-number {
        width: 50px;
        height: 50px;
        background: #2196F3;
        color: white;
        border-radius: 50%;
        display: flex;
        align-items: center;
        justify-content: center;
        font-size: 1.5rem;
        font-weight: 700;
        margin: 0 auto 20px;
    }

    .hed19-step-title {
        font-size: 1.3rem;
        font-weight: 700;
        margin-bottom: 15px;
        color: #333;
    }

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

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

    .hed19-footer-content {
        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: 1.3rem;
        margin-bottom: 20px;
        color: #ecf0f1;
    }

    .hed19-footer-section ul {
        list-style: none;
    }

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

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

    .hed19-footer-section ul li 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;
            width: 100%;
            background: white;
            flex-direction: column;
            padding: 20px;
            box-shadow: 0 2px 10px rgba(0,0,0,0.1);
        }

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

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

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

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

        .hed19-faq-question {
            padding: 20px;
            font-size: 1rem;
        }

        .hed19-faq-item.active .hed19-faq-answer {
            padding: 20px;
        }

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

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

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

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

        .hed19-main-content {
            padding: 40px 15px;
        }

        .hed19-support-header {
            padding: 40px 0;
        }

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

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

        .hed19-contact-section {
            padding: 60px 0;
        }

        .hed19-install-guide {
            padding: 60px 0;
        }
    }