/* Стили страницы player_book; вынесены из шаблона для строгой CSP. */
.player-book-layout { max-width: 1000px; margin: 0 auto; padding: 20px 0; }
.book-intro { font-size: 1.1rem; color: var(--text-color); opacity: 0.85; margin-bottom: 30px; line-height: 1.6; }
.topics-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 20px; }
.topic-card {
    background: var(--card-background);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 25px;
    box-shadow: var(--shadow);
    display: flex;
    flex-direction: column;
    transition: transform 0.2s, box-shadow 0.2s;
    cursor: pointer;
}
.topic-card:hover { transform: translateY(-4px); box-shadow: 0 8px 20px rgba(0,0,0,0.15); }
.topic-icon { font-size: 2.5rem; margin-bottom: 15px; }
.topic-header { font-size: 1.3rem; font-weight: 700; color: var(--primary-color); margin-bottom: 10px; }
.topic-desc { color: var(--text-color); opacity: 0.85; margin-bottom: 20px; flex-grow: 1; line-height: 1.5; font-size: 0.95rem; }
.study-btn { width: 100%; text-align: center; margin-top: auto; cursor: pointer; }

.article-viewer { display: none; animation: fadeIn 0.3s ease forwards; max-width: 900px; margin: 0 auto; }
.article-header { display: flex; align-items: center; gap: 15px; margin-bottom: 25px; padding-bottom: 15px; border-bottom: 2px solid var(--border-color); }
.article-content { line-height: 1.7; color: var(--text-color); font-size: 1.05rem; }
.article-content h3 { color: var(--primary-color); margin-top: 30px; margin-bottom: 12px; border-left: 3px solid var(--primary-color); padding-left: 12px; }
/* Задники под текстом статьи — удобнее читать длинные блоки */
.article-content p {
    margin-bottom: 15px;
    padding: 12px 16px;
    background: var(--card-background);
    border: 1px solid var(--border-color);
    border-radius: 8px;
}
.article-content ul, .article-content ol {
    margin: 0 0 15px;
    padding: 12px 16px 12px 38px;
    background: var(--card-background);
    border: 1px solid var(--border-color);
    border-radius: 8px;
}
.article-content li { margin-bottom: 8px; }
.article-content blockquote { border-left: 4px solid var(--primary-color); padding: 12px 16px; margin: 20px 0; background: var(--card-background); border-radius: 0 8px 8px 0; font-style: italic; }
/* Формулы и «продвинутые» блоки — моноширинная плашка */
.article-content code.article-code {
    display: block; font-family: var(--font-mono, monospace); font-size: 0.95rem;
    background: var(--card-background); border: 1px solid var(--border-color);
    border-radius: 8px; padding: 12px 16px; margin: 15px 0; white-space: pre-wrap;
    overflow-x: auto; color: var(--text-color);
}
.article-content .article-warning {
    color: var(--danger-color);
    border: 1px solid var(--danger-color);
    padding: 12px 16px;
    border-radius: 8px;
    margin: 15px 0;
    background: var(--card-background);
    box-shadow: var(--shadow);
}
@keyframes fadeIn { from { opacity: 0; transform: translateY(5px); } to { opacity: 1; transform: translateY(0); } }
@media (max-width: 768px) {
    .player-book-layout { padding: 10px 0; }
    .book-intro { font-size: 1rem; margin-bottom: 20px; }
    .topic-card { padding: 16px; border-radius: 10px; }
    .topic-icon { font-size: 2rem; margin-bottom: 10px; }
    .topic-header { font-size: 1.1rem; }
    .topic-desc { font-size: 0.88rem; }
    .article-content { font-size: 0.95rem; line-height: 1.6; }
    .article-content p, .article-content ul, .article-content ol { padding: 10px 12px; }
    .article-header { flex-direction: column; align-items: flex-start; gap: 10px; }
}
@media (max-width: 480px) {
    .topic-card { padding: 12px; }
    .topic-header { font-size: 1rem; }
    .article-content { font-size: 0.9rem; }
}