:root {
            --primary: #2563eb;
            --primary-hover: #1d4ed8;
            --bg-color: #f8fafc;
            --text-main: #0f172a;
            --text-muted: #64748b;
            --card-bg: #ffffff;
            --border-color: #e2e8f0;
        }

        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
        }

        body {
            background-color: var(--bg-color);
            color: var(--text-main);
            line-height: 1.6;
        }

        /* Navbar */
        header {
            background: var(--card-bg);
            padding: 1rem 5%;
            display: flex;
            justify-content: space-between;
            align-items: center;
            border-bottom: 1px solid var(--border-color);
            position: sticky;
            top: 0;
            z-index: 100;
        }

        .logo {
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--primary);
            text-decoration: none;
            display: flex;
            align-items: center;
            gap: 8px;
        }

        nav {
            display: flex;
            align-items: center;
            gap: 20px;
        }

        nav a {
            text-decoration: none;
            color: var(--text-muted);
            font-weight: 500;
            transition: color 0.2s;
        }

        nav a:hover {
            color: var(--primary);
        }

        .btn-login {
            background: var(--primary);
            color: white;
            padding: 8px 20px;
            border-radius: 6px;
            font-weight: 500;
            border: none;
            cursor: pointer;
            transition: background 0.2s;
        }

        .btn-login:hover {
            background: var(--primary-hover);
            color: white;
        }

        /* Main Content */
        main {
            padding: 4rem 5%;
            text-align: center;
            min-height: 70vh;
            display: flex;
            flex-direction: column;
            align-items: center;
        }

        .hero h1 {
            font-size: 3rem;
            margin-bottom: 12px;
            font-weight: 800;
            letter-spacing: -0.02em;
        }

        .hero p {
            font-size: 1.1rem;
            color: var(--text-muted);
            margin-bottom: 40px;
            max-width: 600px;
            margin-left: auto;
            margin-right: auto;
        }

        /* Upload Box */
        .upload-box {
            background: var(--card-bg);
            border: 2px dashed #cbd5e1;
            border-radius: 12px;
            padding: 50px;
            width: 100%;
            max-width: 650px;
            transition: all 0.3s ease;
            box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
            position: relative;
        }

        .upload-box:hover,
        .upload-box.dragover {
            border-color: var(--primary);
            background: #f0fdf4;
            box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.05);
        }

        .upload-icon svg {
            width: 64px;
            height: 64px;
            fill: #94a3b8;
            margin-bottom: 20px;
            transition: fill 0.3s;
        }

        .upload-box:hover .upload-icon svg {
            fill: var(--primary);
        }

        .btn-upload {
            background: var(--primary);
            color: white;
            border: none;
            padding: 12px 28px;
            font-size: 1rem;
            border-radius: 6px;
            cursor: pointer;
            font-weight: 500;
            transition: background 0.2s;
            margin-top: 15px;
        }

        .btn-upload:hover {
            background: var(--primary-hover);
        }

        #file-input {
            display: none;
        }

        /* Progress & Messages */
        .progress-container {
            display: none;
            margin-top: 25px;
            text-align: left;
            background: var(--bg-color);
            padding: 15px;
            border-radius: 8px;
            border: 1px solid var(--border-color);
        }

        .progress-bar {
            width: 100%;
            background: #e2e8f0;
            border-radius: 999px;
            overflow: hidden;
            margin-top: 8px;
            height: 8px;
        }

        .progress-fill {
            height: 100%;
            background: var(--primary);
            width: 0%;
            transition: width 0.3s ease;
        }

        .msg {
            margin-top: 20px;
            font-size: 0.95rem;
            color: #b91c1c;
            display: none;
            background: #fef2f2;
            padding: 12px;
            border-radius: 6px;
            border: 1px solid #fecaca;
        }

        /* Features */
        .features {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
            gap: 30px;
            width: 100%;
            max-width: 1000px;
            margin-top: 60px;
        }

        .feature-card {
            background: var(--card-bg);
            padding: 30px;
            border-radius: 12px;
            border: 1px solid var(--border-color);
            box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
            text-align: left;
        }

        .feature-card h3 {
            color: var(--text-main);
            margin-bottom: 12px;
            font-size: 1.25rem;
            display: flex;
            align-items: center;
            gap: 10px;
        }

        .feature-card p {
            color: var(--text-muted);
            font-size: 0.95rem;
            line-height: 1.6;
        }

        /* Modal Styles */
        .modal-overlay {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(15, 23, 42, 0.6);
            backdrop-filter: blur(4px);
            display: none;
            justify-content: center;
            align-items: center;
            z-index: 1000;
        }

        .modal {
            background: var(--card-bg);
            width: 100%;
            max-width: 400px;
            border-radius: 12px;
            padding: 30px;
            box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
            position: relative;
        }

        .close-modal {
            position: absolute;
            top: 15px;
            right: 20px;
            background: none;
            border: none;
            font-size: 1.5rem;
            cursor: pointer;
            color: var(--text-muted);
        }

        .modal h2 {
            margin-bottom: 20px;
            font-size: 1.5rem;
            color: var(--text-main);
        }

        .form-group {
            margin-bottom: 15px;
            text-align: left;
        }

        .form-group label {
            display: block;
            margin-bottom: 5px;
            font-size: 0.9rem;
            color: var(--text-muted);
        }

        .form-group input {
            width: 100%;
            padding: 10px 12px;
            border: 1px solid var(--border-color);
            border-radius: 6px;
            font-size: 1rem;
            outline: none;
            transition: border 0.2s;
        }

        .form-group input:focus {
            border-color: var(--primary);
        }

        .btn-submit {
            width: 100%;
            background: var(--primary);
            color: white;
            border: none;
            padding: 12px;
            font-size: 1rem;
            border-radius: 6px;
            cursor: pointer;
            font-weight: 500;
            margin-top: 10px;
        }

        .btn-submit:disabled {
            opacity: 0.7;
            cursor: not-allowed;
        }

        .auth-error {
            color: #b91c1c;
            font-size: 0.9rem;
            margin-top: 15px;
            display: none;
            text-align: center;
        }

        footer {
            background: #0f172a;
            color: #94a3b8;
            text-align: center;
            padding: 30px 0;
            width: 100%;
            margin-top: auto;
        }

        footer a {
            color: #cbd5e1;
            text-decoration: none;
            margin: 0 12px;
            font-size: 0.9rem;
        }

        footer a:hover {
            color: white;
        }

        @media (max-width: 768px) {
            .hero h1 {
                font-size: 2.2rem;
            }

            nav {
                display: none;
            }

            /* Hide links on mobile for simplicity, keep logo */
        }