:root {
    --primary-color: #3498db;
    --success-color: #2ecc71;
    --danger-color: #e74c3c;
    --dark-color: #34495e;
    --light-color: #f9f9f9;
    --shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    max-width: 1000px;
    margin: 0 auto;
    padding: 20px;
    background-color: #f5f5f5;
}

header {
    text-align: center;
    margin-bottom: 30px;
}

header h1 {
    color: var(--dark-color);
}

#controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding: 15px;
    background: white;
    border-radius: 8px;
    box-shadow: var(--shadow);
}

.input-group {
    display: flex;
    align-items: center;
    gap: 10px;
}

button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 5px;
    cursor: pointer;
    font-weight: bold;
    transition: background-color 0.3s;
}

button:hover {
    background-color: #2980b9;
}

input {
    padding: 8px;
    border: 1px solid #ddd;
    border-radius: 5px;
    width: 60px;
}

.grades-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 15px;
    margin-bottom: 20px;
}

.grade-card {
    background: white;
    border-radius: 8px;
    padding: 15px;
    box-shadow: var(--shadow);
    transition: transform 0.3s;
}

.grade-card:hover {
    transform: translateY(-5px);
}

.score {
    color: var(--primary-color);
    font-weight: bold;
    font-size: 1.1em;
}

.grade {
    color: var(--success-color);
    font-weight: bold;
    font-size: 1.2em;
    margin: 5px 0;
}

.passing {
    color: var(--danger-color);
    font-style: italic;
}

.passing.yes {
    color: var(--success-color);
}

.final-message {
    background: var(--dark-color);
    color: white;
    padding: 20px;
    border-radius: 8px;
    margin-top: 20px;
    font-size: 1.1em;
}

@media (max-width: 600px) {
    #controls {
        flex-direction: column;
        gap: 15px;
        align-items: stretch;
    }
}