:root {
    --primary: #4361ee;
    --secondary: #3f37c9;
    --dark: #212529;
    --light: #f8f9fa;
    --accent: #f72585;
    --gray: #6c757d;
}
.back {
    display: inline-block;
    padding: 10px 20px;
    background-color: #ff007f;
    color: white;
    text-decoration: none;
    font-weight: bold;
    border-radius: 30px;
    box-shadow: 0 4px 15px rgba(255, 0, 127, 0.3);
    transition: all 0.3s ease;
    border: none;
    font-size: 16px;
}
* {
    margin: 0;
    padding: 0;
    font-weight: bold;
    box-sizing: border-box;
    font-family: 'Times New Roman', Times, serif;
}

body {
    background-color: var(--light);
    color: var(--dark);
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

header {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    padding: 2rem 0;
    text-align: center;
    margin-bottom: 2rem;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.last-updated {
    font-style: italic;
    opacity: 0.9;
}

.toc {
    background-color: white;
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 2rem;
    box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}

.toc h2 {
    color: var(--primary);
    margin-bottom: 1rem;
}

.toc-list {
    columns: 2;
    list-style-type: none;
}

.toc-list li {
    margin-bottom: 0.5rem;
    break-inside: avoid;
}

.toc-list a {
    color: var(--gray);
    text-decoration: none;
    transition: color 0.3s;
    display: flex;
    align-items: center;
}

.toc-list a:hover {
    color: var(--accent);
}

.toc-list a::before {
    content: "•";
    color: var(--accent);
    margin-right: 0.5rem;
}

.terms-container {
    background-color: white;
    border-radius: 8px;
    padding: 2rem;
    box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}

.term {
    margin-bottom: 2rem;
    padding-bottom: 1.5rem;
    border-bottom: 1px solid #eee;
}

.term:last-child {
    border-bottom: none;
}

.term h3 {
    color: var(--primary);
    margin-bottom: 0.75rem;
    display: flex;
    align-items: center;
}

.term-number {
    background-color: var(--accent);
    color: white;
    width: 30px;
    height: 30px;
    border-radius: 50%;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    margin-right: 0.75rem;
    font-size: 0.9rem;
}

.term-content {
    color: var(--dark);
}

.term-content p {
    margin-bottom: 0.5rem;
}

.term-content ul {
    margin: 0.5rem 0 1rem 1.5rem;
}

.term-content li {
    margin-bottom: 0.25rem;
}

.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    background-color: var(--accent);
    color: white;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    text-decoration: none;
    box-shadow: 0 2px 10px rgba(0,0,0,0.2);
    opacity: 0;
    transition: opacity 0.3s;
    cursor: pointer;
}

.back-to-top.visible {
    opacity: 1;
}

.back-to-top:hover {
    transform: translateY(-3px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.3);
}

footer {
    text-align: center;
    padding: 2rem;
    color: var(--gray);
    margin-top: 2rem;
}

@media (max-width: 768px) {
    .toc-list {
        columns: 1;
    }
    
    .container {
        padding: 1rem;
    }
    
    h1 {
        font-size: 2rem;
    }
}