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

        html {
            scroll-behavior: smooth;
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvetica Neue', Arial, sans-serif;
            color: #333;
            background-color: #f8f9fa;
            line-height: 1.6;
        }

        .bpxvn-navbar {
            background: #fff;
            box-shadow: 0 2px 8px rgba(0,0,0,0.08);
            position: sticky;
            top: 0;
            z-index: 1000;
        }

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

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

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

        .bpxvn-nav-item a {
            color: #333;
            text-decoration: none;
            font-size: 14px;
            font-weight: 500;
            transition: color 0.3s;
            position: relative;
        }

        .bpxvn-nav-item a:hover {
            color: #ff5722;
        }

        .bpxvn-nav-item a.active::after {
            content: '';
            position: absolute;
            bottom: -8px;
            left: 0;
            right: 0;
            height: 3px;
            background: #ff5722;
            border-radius: 2px;
        }

        .bpxvn-support-header {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: #fff;
            padding: 40px 20px;
            text-align: center;
        }

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

        .bpxvn-support-title {
            font-size: 42px;
            font-weight: 700;
            margin-bottom: 15px;
        }

        .bpxvn-support-subtitle {
            font-size: 18px;
            opacity: 0.95;
            margin-bottom: 30px;
        }

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

        .bpxvn-search-input {
            width: 100%;
            padding: 15px 20px 15px 20px;
            border: none;
            border-radius: 8px;
            font-size: 16px;
            background: #fff;
            color: #333;
        }

        .bpxvn-search-input::placeholder {
            color: #999;
        }

        .bpxvn-search-btn {
            position: absolute;
            right: 5px;
            top: 50%;
            transform: translateY(-50%);
            background: #ff5722;
            border: none;
            padding: 8px 20px;
            border-radius: 6px;
            color: #fff;
            cursor: pointer;
            font-size: 14px;
            transition: background 0.3s;
        }

        .bpxvn-search-btn:hover {
            background: #e64a19;
        }

        .bpxvn-breadcrumb {
            max-width: 1200px;
            margin: 20px auto;
            padding: 0 20px;
            font-size: 13px;
            color: #666;
        }

        .bpxvn-breadcrumb a {
            color: #667eea;
            text-decoration: none;
            transition: color 0.3s;
        }

        .bpxvn-breadcrumb a:hover {
            color: #764ba2;
        }

        .bpxvn-main-content {
            max-width: 1200px;
            margin: 0 auto;
            padding: 40px 20px;
        }

        .bpxvn-category-tabs {
            display: flex;
            gap: 15px;
            margin-bottom: 40px;
            flex-wrap: wrap;
        }

        .bpxvn-category-btn {
            padding: 12px 24px;
            border: 2px solid #ddd;
            background: #fff;
            border-radius: 8px;
            cursor: pointer;
            font-size: 14px;
            font-weight: 600;
            color: #333;
            transition: all 0.3s;
        }

        .bpxvn-category-btn:hover {
            border-color: #667eea;
            color: #667eea;
        }

        .bpxvn-category-btn.active {
            background: #667eea;
            color: #fff;
            border-color: #667eea;
        }

        .bpxvn-content-grid {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 40px;
            margin-bottom: 60px;
        }

        .bpxvn-faq-section {
            grid-column: 1 / -1;
        }

        .bpxvn-section-title {
            font-size: 28px;
            font-weight: 700;
            margin-bottom: 30px;
            color: #222;
            padding-bottom: 15px;
            border-bottom: 3px solid #667eea;
            display: inline-block;
        }

        .bpxvn-quick-links {
            display: grid;
            gap: 15px;
        }

        .bpxvn-quick-link-card {
            padding: 20px;
            background: #fff;
            border-radius: 8px;
            border-left: 4px solid #667eea;
            cursor: pointer;
            transition: all 0.3s;
            box-shadow: 0 2px 4px rgba(0,0,0,0.05);
        }

        .bpxvn-quick-link-card:hover {
            box-shadow: 0 8px 16px rgba(102, 126, 234, 0.15);
            transform: translateX(5px);
        }

        .bpxvn-quick-link-title {
            font-size: 16px;
            font-weight: 600;
            color: #222;
            margin-bottom: 8px;
        }

        .bpxvn-quick-link-desc {
            font-size: 13px;
            color: #666;
            line-height: 1.5;
        }

        .bpxvn-contact-card {
            padding: 25px;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            border-radius: 8px;
            color: #fff;
            margin-bottom: 20px;
        }

        .bpxvn-contact-method {
            margin-bottom: 20px;
        }

        .bpxvn-contact-method:last-child {
            margin-bottom: 0;
        }

        .bpxvn-contact-label {
            font-size: 13px;
            opacity: 0.9;
            margin-bottom: 5px;
        }

        .bpxvn-contact-value {
            font-size: 16px;
            font-weight: 600;
        }

        .bpxvn-faq-list {
            display: grid;
            gap: 15px;
        }

        .bpxvn-faq-item {
            background: #fff;
            border-radius: 8px;
            overflow: hidden;
            box-shadow: 0 2px 4px rgba(0,0,0,0.05);
            transition: all 0.3s;
        }

        .bpxvn-faq-item:hover {
            box-shadow: 0 8px 16px rgba(0,0,0,0.1);
        }

        .bpxvn-faq-question {
            padding: 20px;
            background: #f8f9fa;
            cursor: pointer;
            display: flex;
            justify-content: space-between;
            align-items: center;
            transition: background 0.3s;
        }

        .bpxvn-faq-item.active .bpxvn-faq-question {
            background: #667eea;
            color: #fff;
        }

        .bpxvn-faq-question-text {
            font-size: 15px;
            font-weight: 600;
            flex: 1;
        }

        .bpxvn-faq-toggle {
            font-size: 20px;
            transition: transform 0.3s;
        }

        .bpxvn-faq-item.active .bpxvn-faq-toggle {
            transform: rotate(180deg);
        }

        .bpxvn-faq-answer {
            padding: 0;
            max-height: 0;
            overflow: hidden;
            transition: all 0.3s ease;
        }

        .bpxvn-faq-item.active .bpxvn-faq-answer {
            padding: 20px;
            max-height: 500px;
        }

        .bpxvn-faq-answer-text {
            font-size: 14px;
            color: #666;
            line-height: 1.8;
        }

        .bpxvn-tutorial-section {
            margin-bottom: 60px;
        }

        .bpxvn-tutorial-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
            gap: 25px;
        }

        .bpxvn-tutorial-card {
            background: #fff;
            border-radius: 8px;
            overflow: hidden;
            box-shadow: 0 2px 8px rgba(0,0,0,0.08);
            transition: all 0.3s;
            cursor: pointer;
        }

        .bpxvn-tutorial-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 12px 24px rgba(102, 126, 234, 0.2);
        }

        .bpxvn-tutorial-icon {
            font-size: 48px;
            padding: 25px;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: #fff;
            text-align: center;
        }

        .bpxvn-tutorial-content {
            padding: 20px;
        }

        .bpxvn-tutorial-title {
            font-size: 16px;
            font-weight: 700;
            color: #222;
            margin-bottom: 10px;
        }

        .bpxvn-tutorial-desc {
            font-size: 13px;
            color: #666;
            line-height: 1.6;
            margin-bottom: 15px;
        }

        .bpxvn-tutorial-link {
            color: #667eea;
            text-decoration: none;
            font-size: 13px;
            font-weight: 600;
            transition: color 0.3s;
        }

        .bpxvn-tutorial-link:hover {
            color: #764ba2;
        }

        .bpxvn-step-guide {
            background: #fff;
            border-radius: 8px;
            padding: 30px;
            box-shadow: 0 2px 8px rgba(0,0,0,0.08);
            margin-bottom: 30px;
        }

        .bpxvn-steps {
            display: grid;
            gap: 25px;
        }

        .bpxvn-step {
            display: grid;
            grid-template-columns: 60px 1fr;
            gap: 20px;
            align-items: start;
        }

        .bpxvn-step-number {
            width: 60px;
            height: 60px;
            border-radius: 50%;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: #fff;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 24px;
            font-weight: 700;
            flex-shrink: 0;
        }

        .bpxvn-step-content h4 {
            font-size: 16px;
            color: #222;
            margin-bottom: 8px;
        }

        .bpxvn-step-content p {
            font-size: 14px;
            color: #666;
            line-height: 1.6;
        }

        .bpxvn-troubleshoot {
            background: #fff3cd;
            border-left: 4px solid #ffc107;
            padding: 20px;
            border-radius: 4px;
            margin: 30px 0;
        }

        .bpxvn-troubleshoot-title {
            font-weight: 700;
            color: #856404;
            margin-bottom: 10px;
            font-size: 15px;
        }

        .bpxvn-troubleshoot-list {
            list-style: none;
            padding-left: 0;
        }

        .bpxvn-troubleshoot-item {
            padding: 8px 0;
            color: #856404;
            font-size: 14px;
        }

        .bpxvn-troubleshoot-item::before {
            content: '• ';
            margin-right: 10px;
        }

        .bpxvn-cta-section {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: #fff;
            padding: 50px 20px;
            text-align: center;
            border-radius: 8px;
            margin: 60px 0;
        }

        .bpxvn-cta-title {
            font-size: 28px;
            font-weight: 700;
            margin-bottom: 15px;
        }

        .bpxvn-cta-subtitle {
            font-size: 16px;
            opacity: 0.95;
            margin-bottom: 30px;
            max-width: 600px;
            margin-left: auto;
            margin-right: auto;
        }

        .bpxvn-cta-buttons {
            display: flex;
            gap: 15px;
            justify-content: center;
            flex-wrap: wrap;
        }

        .bpxvn-btn {
            padding: 14px 32px;
            border: none;
            border-radius: 6px;
            font-size: 15px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s;
            text-decoration: none;
            display: inline-block;
        }

        .bpxvn-btn-primary {
            background: #ff5722;
            color: #fff;
        }

        .bpxvn-btn-primary:hover {
            background: #e64a19;
            transform: translateY(-2px);
        }

        .bpxvn-btn-secondary {
            background: #fff;
            color: #667eea;
        }

        .bpxvn-btn-secondary:hover {
            background: #f0f0f0;
            transform: translateY(-2px);
        }

        .bpxvn-footer {
            background: #222;
            color: #aaa;
            padding: 50px 20px 30px;
            margin-top: 80px;
        }

        .bpxvn-footer-container {
            max-width: 1200px;
            margin: 0 auto;
        }

        .bpxvn-footer-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 40px;
            margin-bottom: 40px;
        }

        .bpxvn-footer-col h4 {
            color: #fff;
            font-size: 15px;
            font-weight: 700;
            margin-bottom: 20px;
        }

        .bpxvn-footer-links {
            list-style: none;
            display: grid;
            gap: 12px;
        }

        .bpxvn-footer-links a {
            color: #aaa;
            text-decoration: none;
            font-size: 13px;
            transition: color 0.3s;
        }

        .bpxvn-footer-links a:hover {
            color: #fff;
        }

        .bpxvn-footer-divider {
            border-top: 1px solid #444;
            padding-top: 30px;
            margin-top: 30px;
        }

        .bpxvn-footer-bottom {
            display: flex;
            justify-content: space-between;
            align-items: center;
            flex-wrap: wrap;
            gap: 20px;
            font-size: 13px;
            color: #888;
        }

        .bpxvn-footer-brand {
            font-size: 16px;
            font-weight: 700;
            color: #fff;
        }

        .bpxvn-social-links {
            display: flex;
            gap: 15px;
        }

        .bpxvn-social-links a {
            width: 40px;
            height: 40px;
            border-radius: 50%;
            background: #444;
            display: flex;
            align-items: center;
            justify-content: center;
            color: #aaa;
            text-decoration: none;
            font-size: 18px;
            transition: all 0.3s;
        }

        .bpxvn-social-links a:hover {
            background: #667eea;
            color: #fff;
        }

        @media (max-width: 768px) {
            .bpxvn-navbar-container {
                padding: 0 15px;
                height: 60px;
            }

            .bpxvn-nav-menu {
                gap: 15px;
                font-size: 13px;
            }

            .bpxvn-support-title {
                font-size: 28px;
            }

            .bpxvn-support-subtitle {
                font-size: 15px;
            }

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

            .bpxvn-section-title {
                font-size: 22px;
            }

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

            .bpxvn-step {
                grid-template-columns: 50px 1fr;
            }

            .bpxvn-step-number {
                width: 50px;
                height: 50px;
                font-size: 20px;
            }

            .bpxvn-cta-title {
                font-size: 22px;
            }

            .bpxvn-footer-grid {
                grid-template-columns: repeat(2, 1fr);
                gap: 25px;
            }

            .bpxvn-footer-bottom {
                flex-direction: column;
                align-items: flex-start;
            }
        }

        @media (max-width: 480px) {
            .bpxvn-navbar-container {
                height: auto;
                padding: 15px;
            }

            .bpxvn-nav-menu {
                display: none;
            }

            .bpxvn-support-header {
                padding: 25px 15px;
            }

            .bpxvn-support-title {
                font-size: 22px;
            }

            .bpxvn-search-input {
                padding: 12px 15px;
                font-size: 14px;
            }

            .bpxvn-main-content {
                padding: 20px 15px;
            }

            .bpxvn-category-tabs {
                gap: 10px;
            }

            .bpxvn-category-btn {
                padding: 10px 16px;
                font-size: 12px;
            }

            .bpxvn-section-title {
                font-size: 18px;
            }

            .bpxvn-quick-link-card {
                padding: 15px;
            }

            .bpxvn-step-guide {
                padding: 20px;
            }

            .bpxvn-cta-buttons {
                flex-direction: column;
            }

            .bpxvn-btn {
                width: 100%;
            }

            .bpxvn-footer-grid {
                grid-template-columns: 1fr;
            }
        }