:root {
    --color-year-1: #ffc107;
    --color-year-1-light: #ffd54f;
    --theme-color: var(--color-year-1);
    --theme-color-light: var(--color-year-1-light);
    --bg-color: #f8f9fa;
    --text-dark: #343a40;
    --text-light: #6c757d;
    --card-bg: #ffffff;
    --border-color: #dee2e6;
    --card-shadow: 0 4px 15px rgba(0, 0, 0, 0.06);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Poppins', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-dark);
    line-height: 1.6;
}

.year-header {
    background: linear-gradient(45deg, var(--theme-color), var(--theme-color-light));
    color: white;
    padding: 2rem;
    text-align: center;
    position: relative;
}

.year-header h1 {
    font-size: 2.2rem;
    text-shadow: 1px 1px 3px rgba(0, 0, 0, 0.2);
}

.back-link {
    position: absolute;
    top: 50%;
    left: 2rem;
    transform: translateY(-50%);
    color: white;
    text-decoration: none;
    font-weight: 600;
    background: rgba(255, 255, 255, 0.2);
    padding: 0.5rem 1rem;
    border-radius: 20px;
    transition: background 0.3s ease;
}

.back-link:hover {
    background: rgba(255, 255, 255, 0.3);
}

.container {
    max-width: 900px;
    margin: 2rem auto;
    padding: 0 2rem;
}

main {
    background-color: var(--card-bg);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--card-shadow);
}

main h2 {
    color: var(--theme-color);
    margin-bottom: 1.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border-color);
}

main p {
    margin-bottom: 1rem;
}

.subject-title {
    margin-top: 2rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border-color);
}

.resource-links {
    list-style: none;
    padding: 0;
    margin-top: 1rem;
}

.resource-links li {
    margin-bottom: 0.5rem;
}

.resource-links a {
    display: block;
    text-decoration: none;
    background-color: #f1f3f5;
    color: var(--text-dark);
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-weight: 600;
    border: 1px solid var(--border-color);
    transition: all 0.2s ease-in-out;
}

.resource-links a:hover {
    background-color: #e9ecef;
    transform: translateY(-2px);
    box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}

.term-links {
    list-style: none;
    padding: 0;
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
    flex-wrap: wrap;
}

.term-links li {
    flex: 1 1 150px;
    margin-bottom: 0;
}

.term-links a {
    display: block;
    text-decoration: none;
    background-color: var(--theme-color-light);
    color: white;
    padding: 1rem;
    text-align: center;
    border-radius: 8px;
    font-weight: 600;
    transition: background-color 0.3s ease, transform 0.2s ease;
}

.term-links a:hover {
    background-color: var(--theme-color);
    transform: translateY(-2px);
}

.term-links li.disabled a {
    background-color: #ced4da;
    cursor: not-allowed;
    pointer-events: none;
}

footer {
    text-align: center;
    padding: 2rem 1rem;
    color: var(--text-light);
    font-size: 0.9rem;
}

@media (max-width: 768px) {
    .year-header {
        padding-bottom: 1rem;
    }
    .back-link {
        position: static;
        transform: none;
        display: inline-block;
        margin-top: 1rem;
    }
}