/* Base Variables and Reset */
:root {
    --bg-color: #fcfcfc;
    --text-color: #1a1a1a;
    --text-muted: #666666;
    --border-color: #e0e0e0;
    --font-sans: "Helvetica Neue", Helvetica, Arial, sans-serif;
    --font-serif: "Times New Roman", Times, serif;
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: var(--font-sans);
    line-height: 1.6;
    padding: 40px 20px;
    -webkit-font-smoothing: antialiased;
}

/* Layout */
.container {
    max-width: 1000px;
    margin: 0 auto;
    display: flex;
    flex-wrap: wrap;
    gap: 50px;
}

.sidebar {
    flex: 1 1 300px;
}

.main-content {
    flex: 2 1 600px;
}

/* Sidebar Elements */
.book-cover {
    width: 100%;
    aspect-ratio: 2 / 3;
    background-color: #eee;
    border: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 25px;
    color: var(--text-muted);
    font-size: 0.9em;
    letter-spacing: 1px;
    text-transform: uppercase;
}

.meta-info {
    font-size: 0.85em;
    color: var(--text-muted);
}

.meta-info p {
    margin-bottom: 8px;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 8px;
    display: flex;
    justify-content: space-between;
}

.meta-info p.meta-note {
    border-bottom: none;
    margin-top: 15px;
    text-transform: none;
    text-align: justify;
}

/* Main Content Typography */
h1 {
    font-family: var(--font-serif);
    font-size: 2.8em;
    font-weight: normal;
    line-height: 1.1;
    margin-bottom: 5px;
}

.subtitle {
    font-size: 1.2em;
    color: var(--text-muted);
    margin-bottom: 30px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

h3 {
    font-size: 1.1em;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin: 40px 0 20px 0;
    border-bottom: 2px solid var(--text-color);
    padding-bottom: 10px;
}

.description p {
    margin-bottom: 20px;
    font-size: 1.05em;
}

/* Download Section */
.download-box {
    background-color: #fff;
    border: 1px solid var(--border-color);
    padding: 30px;
    text-align: center;
    margin-bottom: 40px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.03);
}

.download-box h2 {
    font-family: var(--font-serif);
    font-weight: normal;
    margin-bottom: 10px;
}

.download-desc {
    color: var(--text-muted);
}

.download-btn {
    display: inline-block;
    background-color: var(--text-color);
    color: #fff;
    text-decoration: none;
    padding: 14px 35px;
    font-size: 1em;
    text-transform: uppercase;
    letter-spacing: 2px;
    margin-top: 15px;
    transition: background-color 0.2s ease;
}

.download-btn:hover {
    background-color: #444;
}

.file-meta {
    font-size: 0.8em;
    color: var(--text-muted);
    margin-top: 15px;
    text-transform: uppercase;
}

/* Lists and Tables */
.contributors {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 10px;
    font-size: 0.95em;
    color: var(--text-muted);
}

.toc {
    margin-top: 40px;
}

.toc-item {
    display: flex;
    justify-content: space-between;
    border-bottom: 1px solid var(--border-color);
    padding: 12px 0;
    font-size: 0.95em;
}

.toc-title {
    font-weight: bold;
    color: var(--text-color);
}

.toc-author {
    color: var(--text-muted);
    text-align: right;
    font-style: italic;
}

/* Responsive */
@media (max-width: 768px) {
    .container {
        flex-direction: column;
        gap: 30px;
    }
    
    .sidebar {
        display: contents; 
    }

    .book-cover {
        order: 1;
        margin-bottom: 0; 
    }

    .meta-info {
        order: 2;
        margin-top: -10px;
        padding-bottom: 30px;
        border-bottom: 1px solid var(--border-color);
    }

    .main-content {
        order: 3;
    }

    h1 {
        font-size: 2.2em;
    }
}