:root {
            --brand-green: #2E8B57;
            --brand-dark-green: #256d44;
            --background-color: #F9F6F2;
            --text-color: #333333;
            --card-background: #FFFFFF;
            --shadow-color: rgba(0, 0, 0, 0.08);
            --section-bg-1: #EBF5EE;
            --section-bg-2: #FEF6E8;
            --section-bg-3: #E8F1F5;
        }

        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Nunito', sans-serif;
            scroll-behavior: smooth;
        }

        body {
            background-color: var(--background-color);
            color: var(--text-color);
            overflow-x: hidden;
        }

        .wavy-underline {
            background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 12'%3E%3Cpath d='M0 6 Q 25 12, 50 6 T 100 6' stroke='%232E8B57' stroke-width='3' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
            background-repeat: no-repeat;
            background-position: bottom center;
            background-size: 100% 12px;
            padding-bottom: 12px;
        }

        .navbar {
            position: fixed;
            top: 0;
            width: 100%;
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 15px 5%;
            background: rgba(249, 246, 242, 0.85);
            backdrop-filter: blur(10px);
            border-bottom: 1px solid rgba(0,0,0,0.1);
            z-index: 1000;
        }

        .brand {
            display: flex;
            align-items: center;
            cursor: pointer;
        }

        .brand img {
            width: 50px;
            margin-right: 15px;
        }

        .brand h1 {
            font-size: 1.4rem;
            font-weight: 800;
            color: var(--text-color);
        }

        .nav-links {
            list-style-type: none;
            display: flex;
            gap: 15px;
        }

        .nav-links li, .nav-links li a {
            padding: 8px 15px;
            font-weight: 700;
            font-size: 1rem;
            cursor: pointer;
            text-decoration: none;
            color: var(--text-color);
            border-radius: 20px;
            transition: all 0.3s ease;
        }

        .nav-links li:hover, .nav-links li a:hover {
            background-color: var(--brand-green);
            color: white;
        }

        .hero-container {
            display: flex;
            justify-content: center;
            align-items: center;
            min-height: 90vh;
            padding: 100px 5% 50px;
            text-align: center;
        }

        .hero-content {
            max-width: 800px;
        }

        .hero-content h2 {
            font-size: 4.5rem;
            font-weight: 800;
            line-height: 1.1;
            margin-bottom: 30px;
        }

        .hero-content .cta-button {
            color: white;
            background-color: var(--brand-green);
            padding: 15px 40px;
            border: none;
            border-radius: 50px;
            text-decoration: none;
            font-size: 1.2rem;
            font-weight: 700;
            cursor: pointer;
            transition: all 0.3s ease;
            box-shadow: 0 4px 15px rgba(46, 139, 87, 0.4);
        }

        .hero-content .cta-button:hover {
            transform: translateY(-3px);
            background-color: var(--brand-dark-green);
            box-shadow: 0 6px 20px rgba(46, 139, 87, 0.5);
        }
        
        .hero-divider {
            margin-top: 50px;
            height: 20px;
            width: 150px;
            background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 12'%3E%3Cpath d='M0 6 Q 25 12, 50 6 T 100 6' stroke='%23dddddd' stroke-width='3' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
            background-repeat: no-repeat;
            background-position: center;
            background-size: contain;
        }

        .content-section {
            min-height: 100vh;
            padding: 100px 8%;
            display: flex;
            flex-direction: column;
            align-items: center;
        }
        
        #secnoithat { background-color: var(--section-bg-1); }
        #secit { background-color: var(--section-bg-2); }
        #secgraphic { background-color: var(--section-bg-3); }
        #secvideo { background-color: var(--section-bg-1); }
        #secmod { background-color: var(--section-bg-2); }

        .section-title {
            font-size: 3.5rem;
            font-weight: 800;
            margin-bottom: 80px;
            display: inline-block;
        }

        .software-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
            gap: 40px;
            width: 100%;
        }

        .software-card {
            background: var(--card-background);
            border-radius: 20px;
            padding: 25px;
            text-align: center;
            transition: transform 0.3s ease, box-shadow 0.3s ease;
            box-shadow: 0px 8px 24px var(--shadow-color);
            display: flex;
            flex-direction: column;
        }

        .software-card:hover {
            transform: translateY(-8px);
            box-shadow: 0px 12px 30px rgba(0, 0, 0, 0.12);
        }

        .software-card .logo-container {
            height: 120px;
            display: flex;
            justify-content: center;
            align-items: center;
            margin-bottom: 20px;
        }
        
        .software-card .logo-container img {
            max-width: 120px;
            max-height: 100%;
            object-fit: contain;
        }

        .software-card h3 {
            font-size: 1.5rem;
            font-weight: 700;
            margin-bottom: 20px;
            flex-grow: 1;
        }

        .download-links {
            display: flex;
            flex-direction: column;
            gap: 12px;
            margin-top: auto;
        }

        .download-links a {
            text-decoration: none;
            color: var(--brand-green);
            background: var(--section-bg-1);
            padding: 12px;
            border-radius: 12px;
            font-weight: 700;
            transition: all 0.3s;
        }

        .download-links a:hover {
            background-color: var(--brand-green);
            color: white;
            transform: scale(1.05);
        }
        
        .download-links a.disabled {
            background: #e0e0e0;
            color: #999;
            cursor: not-allowed;
            pointer-events: none;
        }

        .section-tutorial-wrapper {
            margin-top: 60px;
            width: 100%;
            text-align: center;
        }

        .section-tutorial-link {
            display: inline-flex;
            align-items: center;
            gap: 10px;
            background-color: var(--brand-dark-green);
            color: white;
            padding: 12px 28px;
            border-radius: 50px;
            text-decoration: none;
            font-size: 1.1rem;
            font-weight: 700;
            transition: all 0.3s ease;
            box-shadow: 0 4px 15px rgba(0,0,0,0.1);
        }

        .section-tutorial-link:hover {
            transform: translateY(-3px);
            box-shadow: 0 6px 20px rgba(0,0,0,0.15);
        }

        .section-tutorial-link svg {
            width: 18px;
            height: 18px;
            fill: currentColor;
        }

        .hidden {
            opacity: 0;
            filter: blur(5px);
            transform: translateY(50px);
            transition: all 1s cubic-bezier(0.165, 0.84, 0.44, 1);
        }

        .show {
            opacity: 1;
            filter: blur(0);
            transform: translateY(0);
        }

        #progress {
            position: fixed;
            bottom: 30px;
            right: 30px;
            height: 55px;
            width: 55px;
            display: grid;
            place-items: center;
            border-radius: 50%;
            background: var(--card-background);
            box-shadow: 0 5px 15px rgba(0,0,0,0.15);
            cursor: pointer;
            z-index: 999;
            opacity: 0;
            transform: scale(0.8);
            transition: opacity 0.4s, transform 0.4s;
        }
        #progress.active {
            opacity: 1;
            transform: scale(1);
        }
        #progress:hover {
            transform: scale(1.1) !important;
        }
        #progress-button {
            font-size: 28px;
            color: var(--brand-green);
            background: none;
            border: none;
            cursor: pointer;
        }

        /* --- CSS CHO CHATBOT (Đã cập nhật) --- */
        .message {
            padding: 10px 15px; /* Tăng padding một chút */
            border-radius: 18px;
            max-width: 85%; /* Cho phép tin nhắn rộng hơn một chút nếu cần */
            word-wrap: break-word;
            line-height: 1.5; /* Cải thiện khả năng đọc */
            margin-bottom: 8px; /* Khoảng cách giữa các tin nhắn */
        }
        .user-message {
            background-color: var(--brand-green);
            color: white;
            align-self: flex-end; 
            margin-left: auto; 
            border-bottom-right-radius: 5px; /* Tạo kiểu dáng khác biệt một chút */
        }
        .bot-message {
            background-color: #FFFFFF; /* Nền trắng cho tin nhắn bot */
            color: var(--text-color);
            align-self: flex-start; 
            margin-right: auto;
            border: 1px solid var(--section-bg-1); /* Thêm viền nhẹ */
            border-bottom-left-radius: 5px; /* Tạo kiểu dáng khác biệt một chút */
            box-shadow: 0 2px 5px rgba(0,0,0,0.05); /* Thêm bóng đổ nhẹ cho cảm giác nổi bật */
        }
        /* --- KẾT THÚC CSS CHATBOT --- */