:root {
            --primary-color: #0a192f;
            --accent-color: #d97706;
            --border-color: #cbd5e1;
            --bg-light: #f8fafc;
        }

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background-color: var(--bg-light);
            color: #334155;
            margin: 0;
            padding: 20px;
        }

        .container {
            max-width: 850px;
            margin: 0 auto;
            background: #ffffff;
            border: 1px solid var(--border-color);
            border-radius: 8px;
            padding: 30px;
            box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
        }

        .header-libro {
            text-align: center;
            border-bottom: 2px solid var(--primary-color);
            padding-bottom: 15px;
            margin-bottom: 25px;
        }

        .header-libro h1 {
            color: var(--primary-color);
            margin: 0 0 5px 0;
            font-size: 1.5rem;
            text-transform: uppercase;
        }

        .hoja-info {
            display: flex;
            justify-content: space-between;
            background-color: #f1f5f9;
            padding: 10px 15px;
            border-radius: 6px;
            font-weight: 600;
            font-size: 0.9rem;
            margin-bottom: 20px;
        }

        .section-title {
            background-color: var(--primary-color);
            color: #ffffff;
            padding: 8px 12px;
            font-size: 0.95rem;
            font-weight: bold;
            border-radius: 4px;
            margin-top: 20px;
            margin-bottom: 15px;
            text-transform: uppercase;
        }

        .form-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
            gap: 15px;
        }

        .form-group {
            display: flex;
            flex-direction: column;
        }

        .form-group.full-width {
            grid-column: 1 / -1;
        }

        label {
            font-size: 0.85rem;
            font-weight: 600;
            margin-bottom: 5px;
            color: #475569;
        }

        input[type="text"],
        input[type="email"],
        input[type="tel"],
        input[type="date"],
        input[type="number"],
        select,
        textarea {
            padding: 10px;
            border: 1px solid var(--border-color);
            border-radius: 4px;
            font-size: 0.9rem;
            outline: none;
            transition: border-color 0.2s;
        }

        input:focus, select:focus, textarea:focus {
            border-color: var(--primary-color);
        }

        .radio-group {
            display: flex;
            gap: 20px;
            align-items: center;
            margin-top: 5px;
        }

        .radio-group label {
            font-weight: normal;
            cursor: pointer;
        }

        .info-box {
            font-size: 0.8rem;
            color: #64748b;
            background: #fffbe3;
            border-left: 4px solid var(--accent-color);
            padding: 10px;
            margin-top: 10px;
            border-radius: 0 4px 4px 0;
        }

        .legal-terms {
            font-size: 0.75rem;
            color: #64748b;
            margin-top: 20px;
            line-height: 1.4;
        }

        .btn-submit {
            background-color: var(--primary-color);
            color: white;
            border: none;
            padding: 12px 25px;
            font-size: 1rem;
            font-weight: bold;
            border-radius: 6px;
            cursor: pointer;
            width: 100%;
            margin-top: 20px;
            transition: background 0.2s;
        }

        .btn-submit:hover {
            background-color: #1e3a8a;
        }