/* --- RESET & BASIC --- */
        * { margin: 0; padding: 0; box-sizing: border-box; }
        html { scroll-behavior: smooth; }
        body { 
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; 
            color: #1f2937;
            line-height: 1.6;
            background-color: #fff;
        }
        .container { max-width: 1200px; margin: 0 auto; padding: 0 1.5rem; }
        a { text-decoration: none; color: inherit; transition: 0.3s; }
        
        /* --- HEADER --- */
        header {
            background: rgba(255, 255, 255, 0.95);
            backdrop-filter: blur(10px);
            box-shadow: 0 4px 6px rgba(0,0,0,0.07);
            position: sticky;
            top: 0;
            z-index: 1000;
        }
        nav {
            display: flex;
            justify-content: space-between;
            align-items: center;
            height: 75px;
        }
        .logo {
            font-size: 1.75rem;
            font-weight: 900;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            cursor: pointer;
        }
        .nav-links { display: flex; gap: 2rem; align-items: center; }
        .nav-links a { font-weight: 600; color: #4b5563; font-size: 0.95rem; }
        .nav-links a:hover { color: #667eea; }

        /* --- HERO --- */
        .hero {
            padding: 6rem 0 8rem; /* Tăng padding bottom để chừa chỗ cho Stats */
            text-align: center;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            border-radius: 0 0 50% 50% / 4%; /* Tạo đường cong nhẹ dưới đáy */
        }
        .hero h1 { font-size: 3.5rem; margin-bottom: 1.5rem; line-height: 1.2; font-weight: 800; }
        .hero p { font-size: 1.3rem; max-width: 750px; margin: 0 auto 2.5rem; opacity: 0.9; }
        .app-buttons { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; }
        .btn {
            display: inline-flex;
            align-items: center;
            padding: 1rem 2rem;
            background: white;
            color: #667eea;
            border-radius: 12px;
            font-weight: 700;
            font-size: 1.05rem;
            box-shadow: 0 10px 25px rgba(0,0,0,0.2);
            transition: all 0.3s;
        }
        .btn:hover { transform: translateY(-3px); box-shadow: 0 15px 35px rgba(0,0,0,0.3); }
        .btn-outline { background: transparent; border: 2px solid rgba(255,255,255,0.8); color: white; box-shadow: none; }
        .btn-outline:hover { background: white; color: #667eea; border-color: white; }

        /* --- STATS --- */
        .stats {
            margin-top: -4rem; /* Kéo lên đè lên Hero */
            position: relative;
            z-index: 10;
        }
        .stats-box {
            background: white;
            border-radius: 20px;
            padding: 3rem 2rem;
            box-shadow: 0 20px 40px rgba(0,0,0,0.1);
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 2rem;
            text-align: center;
        }
        .stat-number {
            font-size: 2.5rem;
            font-weight: 900;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            margin-bottom: 0.5rem;
        }
        .stat-label { color: #6b7280; font-weight: 600; font-size: 1rem; }

        /* --- FEATURES --- */
        .features { padding: 6rem 0; background: white; }
        .section-title { text-align: center; margin-bottom: 4rem; }
        .section-title h2 { font-size: 2.5rem; margin-bottom: 1rem; color: #111827; font-weight: 800; }
        .section-title p { color: #6b7280; font-size: 1.2rem; max-width: 600px; margin: 0 auto; }
        
        .feature-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
            gap: 2.5rem;
        }
        .card {
            background: white;
            padding: 2.5rem;
            border-radius: 20px;
            box-shadow: 0 10px 30px rgba(0, 0, 0, 0.05);
            transition: all 0.4s;
            border: 1px solid #f3f4f6;
        }
        .card:hover { transform: translateY(-10px); box-shadow: 0 20px 40px rgba(102, 126, 234, 0.15); border-color: #e5e7eb; }
        .icon-box {
            width: 60px;
            height: 60px;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            display: flex;
            align-items: center;
            justify-content: center;
            border-radius: 16px;
            margin-bottom: 1.5rem;
        }
        .card h3 { margin-bottom: 1rem; font-size: 1.3rem; font-weight: 700; }
        .card p { color: #6b7280; line-height: 1.7; font-size: 1rem; }

        /* --- HOW IT WORKS --- */
        .how-it-works { padding: 6rem 0; background: linear-gradient(135deg, #f8f9ff 0%, #f0f4ff 100%); }
        .steps {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
            gap: 3rem;
        }
        .step {
            text-align: center;
            padding: 2.5rem;
            background: white;
            border-radius: 20px;
            box-shadow: 0 10px 30px rgba(0,0,0,0.05);
            transition: all 0.3s;
        }
        .step:hover { transform: translateY(-10px); }
        .step-number {
            width: 70px;
            height: 70px;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 2rem;
            font-weight: 800;
            margin: 0 auto 1.5rem;
            box-shadow: 0 10px 20px rgba(118, 75, 162, 0.3);
        }

        /* --- PRICING --- */
        .pricing { padding: 6rem 0; background: white; }
        .pricing-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 2rem;
            max-width: 1000px;
            margin: 0 auto;
        }
        .pricing-card {
            background: white;
            padding: 3rem 2rem;
            border-radius: 24px;
            border: 1px solid #e5e7eb;
            text-align: center;
            transition: all 0.3s;
            position: relative;
        }
        .pricing-card:hover { transform: translateY(-10px); box-shadow: 0 20px 40px rgba(0,0,0,0.1); }
        .pricing-card.featured {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            border: none;
            transform: scale(1.05);
            box-shadow: 0 20px 40px rgba(118, 75, 162, 0.2);
            z-index: 2;
        }
        .pricing-card.featured:hover { transform: scale(1.05) translateY(-10px); }
        
        .plan-name { font-size: 1.25rem; font-weight: 700; margin-bottom: 1rem; text-transform: uppercase; letter-spacing: 1px; }
        .price { font-size: 3rem; font-weight: 900; color: #1f2937; margin-bottom: 0.5rem; }
        .pricing-card.featured .price { color: white; }
        .price span { font-size: 1rem; color: #9ca3af; font-weight: 500; }
        .pricing-card.featured .price span { color: rgba(255,255,255,0.7); }
        
        .pricing-features { list-style: none; margin: 2rem 0; text-align: left; }
        .pricing-features li { padding: 0.75rem 0; color: #4b5563; font-size: 1rem; border-bottom: 1px solid #f3f4f6; }
        .pricing-card.featured .pricing-features li { color: rgba(255,255,255,0.9); border-bottom: 1px solid rgba(255,255,255,0.1); }
        .pricing-features li::before { content: '✓'; color: #10b981; font-weight: 900; margin-right: 0.75rem; }
        .pricing-card.featured .pricing-features li::before { color: #fbbf24; }

        .btn-pricing {
            display: block;
            width: 100%;
            padding: 1rem;
            border-radius: 12px;
            font-weight: 700;
            margin-top: 1rem;
            background: #f3f4f6;
            color: #1f2937;
        }
        .pricing-card.featured .btn-pricing {
            background: #fbbf24;
            color: #78350f;
            box-shadow: 0 5px 15px rgba(251, 191, 36, 0.3);
        }

        /* --- FAQ --- */
        .faq { padding: 6rem 0; background: #f9fafb; }
        .faq-grid { max-width: 800px; margin: 0 auto; }
        .faq-item {
            background: white;
            margin-bottom: 1rem;
            border-radius: 12px;
            padding: 1.5rem 2rem;
            box-shadow: 0 2px 5px rgba(0,0,0,0.05);
        }
        .faq-item h3 { font-size: 1.1rem; margin-bottom: 0.5rem; font-weight: 700; color: #1f2937; }
        .faq-item p { color: #6b7280; margin: 0; }

        /* --- CTA --- */
        .cta {
            padding: 5rem 0;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            text-align: center;
        }
        .cta h2 { font-size: 2.5rem; margin-bottom: 1rem; }
        .cta p { font-size: 1.2rem; margin-bottom: 2.5rem; opacity: 0.9; }

        /* --- FOOTER --- */
        footer { background: #1f2937; color: #d1d5db; padding: 4rem 0 2rem; }
        .footer-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 3rem;
            margin-bottom: 3rem;
        }
        .footer-col h4 { color: white; margin-bottom: 1.5rem; font-size: 1.2rem; }
        .footer-col ul { list-style: none; }
        .footer-col ul li { margin-bottom: 0.75rem; }
        .footer-col a:hover { color: white; text-decoration: underline; }
        .footer-bottom { text-align: center; padding-top: 2rem; border-top: 1px solid #374151; font-size: 0.9rem; }

        /* --- MOBILE --- */
        @media (max-width: 768px) {
            .hero h1 { font-size: 2.5rem; }
            nav { flex-direction: column; height: auto; padding: 1rem 0; gap: 1rem; }
            .nav-links { gap: 1rem; flex-wrap: wrap; justify-content: center; }
            .pricing-card.featured { transform: scale(1); }
            .pricing-card.featured:hover { transform: scale(1); }
            .about-grid { grid-template-columns: 1fr; gap: 2rem; }
        }
        /* --- ABOUT SECTION --- */
.about-section { padding: 6rem 0; background: white; }
.about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}
.about-content h2 { 
    font-size: 2.25rem; 
    margin-bottom: 1.5rem; 
    line-height: 1.3; 
    font-weight: 800;
}
.about-content p { 
    margin-bottom: 1rem; 
    color: #6b7280; 
    text-align: justify; 
    font-size: 1.05rem;
}
.highlight-box {
    background: #eff6ff;
    border-left: 4px solid #667eea;
    padding: 1.5rem;
    margin: 1.5rem 0;
    border-radius: 0 8px 8px 0;
    color: #1f2937;
}
.dashboard-img {
    max-width: 100%;
    height: auto;
    border-radius: 16px;
    box-shadow: 0 20px 40px rgba(0,0,0,0.1);
}
/* --- VIDEO DEMO SECTION --- */
/* --- VERTICAL VIDEO DEMO (VIDEO DỌC) --- */
.video-demo { 
    padding: 6rem 0; 
    background: #f8f9ff; 
    text-align: center; 
}

.phone-video-wrapper {
    position: relative;
    width: 100%;
    /* Giới hạn chiều rộng bằng kích thước đt thật để không bị khổng lồ trên máy tính */
    max-width: 320px; 
    margin: 0 auto;
    /* Đảo ngược tỷ lệ thành 9:16 cho video dọc */
    aspect-ratio: 9 / 16; 
    
    /* Các thuộc tính mô phỏng vỏ điện thoại */
    border-radius: 32px; 
    border: 10px solid #1f2937; /* Viền đen dày giống viền đt */
    box-shadow: 0 25px 50px rgba(0,0,0,0.2); /* Bóng đổ 3D */
    overflow: hidden;
    background-color: #000;
}

.phone-video-wrapper iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: none;
}
/* --- SỬA LỖI GIAO DIỆN ABOUT TRÊN MOBILE --- */
@media (max-width: 768px) {
    .about-grid { 
        grid-template-columns: 1fr; /* Ép về 1 cột trên điện thoại */
        gap: 2rem; 
    }
    
    .about-image {
        display: flex;
        justify-content: center; /* Căn giữa hình ảnh trên điện thoại */
        margin-top: 1rem;
    }
    
    .about-image img {
        max-width: 80%; /* Thu nhỏ ảnh lại một chút cho cân đối với chữ */
    }
}