:root {
    --primary-dark: #1a2a44;
    --primary-light: #00b7eb;
    --card-dark: #4682b4;
    --card-light: #87cefa;
    --background: #f5f7fa;
    --text-dark: #333;
    --text-light: #fff;
    --shadow: rgba(0, 0, 0, 0.2);
}

body {
    font-family: 'Cairo', sans-serif;
    background: var(--background);
    color: var(--text-dark);
    margin: 0;
    padding: 0;
    overflow-x: hidden;
    scroll-behavior: smooth;
    direction: rtl;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

header {
    background: linear-gradient(135deg, var(--primary-dark), var(--primary-light));
    padding: 15px 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 4px 12px var(--shadow);
    position: relative;
    z-index: 10;
}

header h1 {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--text-light);
    margin: 0;
}

.btn-back {
    background: rgba(255, 255, 255, 0.2);
    color: var(--text-light);
    padding: 8px 18px;
    border-radius: 25px;
    font-size: 1rem;
    font-weight: 500;
    text-decoration: none;
    transition: all 0.3s ease;
}

.btn-back:hover {
    background: var(--text-light);
    color: #007bff;
    transform: translateY(-2px);
}

main {
    padding: 30px 15px;
    max-width: 1200px;
    margin: 0 auto;
    text-align: center;
    flex: 1;
}

.subject {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
    list-style: none;
    padding: 0;
}

.subject li {
    display: flex;
}

.subject li a {
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--card-dark) 0%, var(--card-light) 100%);
    border-radius: 12px;
    padding: 30px;
    min-height: 250px;
    color: var(--text-light);
    font-size: 1.6rem;
    font-weight: 600;
    text-decoration: none;
    text-align: center;
    transition: transform 0.3s ease, box-shadow 0.3s ease, background 0.3s ease;
    flex: 1;
    word-wrap: break-word;
}

.subject li a:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px var(--shadow);
    background: linear-gradient(135deg, var(--card-light) 0%, var(--card-dark) 100%);
}

footer {
    background: linear-gradient(135deg, var(--primary-dark), var(--primary-light));
    padding: 10px;
    text-align: center;
    color: var(--text-light);
    font-size: 0.9rem;
    font-weight: 500;
    box-shadow: 0 -5px 15px rgba(0, 183, 235, 0.3);
    margin-top: auto;
}

@media (max-width: 1024px) {
    .subject {
        grid-template-columns: repeat(2, 1fr);
        gap: 15px;
    }

    .subject li a {
        min-height: 200px;
        padding: 25px;
        font-size: 1.4rem;
    }
}

@media (max-width: 768px) {
    header {
        padding: 10px 20px;
    }

    header h1 {
        font-size: 1.5rem;
    }

    .btn-back {
        padding: 6px 15px;
        font-size: 0.9rem;
    }

    .subject {
        grid-template-columns: repeat(2, 1fr);
        gap: 12px;
    }

    .subject li a {
        min-height: 180px;
        padding: 20px;
        font-size: 1.3rem;
    }

    footer {
        padding: 8px;
        font-size: 0.8rem;
    }
}

@media (max-width: 480px) {
    .subject {
        grid-template-columns: 1fr;
        gap: 10px;
    }

    .subject li a {
        min-height: 150px;
        padding: 15px;
        font-size: 1.2rem;
    }
}