:root {
            --primary: #6366f1;
            /* Indigo */
            --primary-hover: #4f46e5;
            --secondary: #ec4899;
            /* Pink */
            --bg-color: #f8fafc;
            --surface: #ffffff;
            --text-main: #1e293b;
            --text-muted: #64748b;
            --radius-lg: 16px;
            --radius-md: 12px;
            --shadow-soft: 0 10px 25px -5px rgba(0, 0, 0, 0.05);
            --shadow-hover: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
            --transition: all 0.3s cubic;
        }

        body {
            font-family: 'Outfit', sans-serif;
            background-color: var(--bg-color);
            background-image:
                radial-gradient(at 0% 0%, hsla(253, 16%, 7%, 0.05) 0, transparent 50%),
                radial-gradient(at 100% 0%, hsla(339, 49%, 30%, 0.05) 0, transparent 50%);
            color: var(--text-main);
            margin: 0;
            padding: 0;
            min-height: 100vh;
            line-height: 1.6;
        }
  
  h2 {
            font-size: 2.5rem;
            font-weight: 800;
            margin: 0.5rem 0;
        }

h3 {        font-size: 1.25rem;
            font-weight: 400;
            opacity: 0.9;
            margin: 0;
        }
p    {color: #333; font-size: 16px; line-height: 1.5;}
span {font-style: italic; font-size: 18px; font-weight: normal; vertical-align: middle;}
span.grande{font-size: 30px; font-weight: normal; vertical-align: middle;}
span.mediano{font-size: 20px; font-weight: normal; vertical-align: middle;}
span.small{font-size: 12px; font-weight: normal;}

 .header-container {
            text-align: center;
            padding: 3rem 1rem;
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            color: white;
            box-shadow: var(--shadow-soft);
            margin-bottom: 2rem;
        }
.nav-links {
            display: flex;
            justify-content: center;
            gap: 2rem;
            margin: 2rem 0;
            flex-wrap: wrap;
        }

.nav-links a {
            color: var(--text-muted);
            text-decoration: none;
            font-weight: 600;
            padding: 0.5rem 1.5rem;
            border-radius: 50px;
            background: white;
            box-shadow: var(--shadow-soft);
            transition: var(--transition);
        }
.nav-links a:hover {
            color: var(--primary);
            box-shadow: var(--shadow-hover);
            transform: translateY(-2px);
    }

hr {
            border: none;
            border-top: 2px dashed #e2e8f0;
            margin: 2rem 0;
    }

.grid-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: 20px;
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

.card {
    background: #fff;
    border-radius: 10px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    padding: 20px;
    transition: transform 0.2s;
    border-top: 5px solid #3498db;
    display: flex;
    flex-direction: column;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 6px 12px rgba(0,0,0,0.15);
}

.card-header {
    font-weight: bold;
    color: #2c3e50;
    margin-bottom: 15px;
    font-size: 18px;
    border-bottom: 2px solid #ecf0f1;
    padding-bottom: 10px;
}

.exercise-content {
    margin-bottom: 20px;
    padding: 15px;
    background-color: #f9f9f9;
    border-radius: 8px;
    text-align: center;
    min-height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.options-container {
    margin-bottom: 15px;
    flex-grow: 1;
}

.options-container label {
    display: block;
    margin-bottom: 10px;
    cursor: pointer;
    padding: 8px 12px;
    border-radius: 6px;
    transition: background-color 0.2s;
    border: 1px solid transparent;
}

.options-container label:hover {
    background-color: #e8f4f8;
    border-color: #bde0ef;
}

.feedback {
    margin-top: 15px;
    padding: 12px;
    border-radius: 6px;
    font-weight: bold;
    text-align: center;
    display: none;
    font-size: 16px;
}

.feedback.correct {
    display: block;
    background-color: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.feedback.incorrect {
    display: block;
    background-color: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

.feedback.unanswered {
    display: block;
    background-color: #fff3cd;
    color: #856404;
    border: 1px solid #ffeeba;
}

.eval-controls {
    text-align: center;
    margin: 30px auto;
    padding: 25px;
    background: #fff;
    border-radius: 10px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    max-width: 500px;
}

button#But1 {
    background-color: #e67e22;
    color: white;
    border: none;
    padding: 14px 28px;
    font-size: 20px;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.3s;
    font-weight: bold;
    margin-bottom: 15px;
}

button#But1:hover {
    background-color: #d35400;
}

button#But1:disabled {
    background-color: #bdc3c7;
    cursor: not-allowed;
}

input[name='calif'] {
    font-size: 20px;
    font-weight: bold;
    color: #2c3e50;
    text-align: center;
    border: 2px solid #bdc3c7;
    border-radius: 5px;
    padding: 5px;
    width: 60px;
}