:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --text-primary: #2c3e50;
    --text-secondary: #34495e;
    --accent: #3498db;
    --border: #eee;
    --qa-bg: #f0f7ff;
    --qa-hover: #e1eeff;
    --answer-bg: #f8f9fa;
}

[data-theme="dark"] {
    --bg-primary: #1a1a1a;
    --bg-secondary: #222;
    --text-primary: #f0f0f0;
    --text-secondary: #e0e0e0;
    --accent: #5dade2;
    --border: #444;
    --qa-bg: #2a394a;
    --qa-hover: #3a495a;
    --answer-bg: #232f3e;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    margin: 0;
    padding: 20px;
    transition: background-color 0.3s, color 0.3s;
}

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

header {
    text-align: center;
    margin-bottom: 30px;
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px; /* Расстояние между элементами */
    padding: 15px;
}

h1 {
    color: var(--text-secondary);
    margin-bottom: 15px;
}

.theme-toggle {
    background: none;
    border: 1px solid var(--border);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    font-size: 16px;
    cursor: pointer;
    color: var(--text-primary);
    background-color: var(--bg-secondary);
    transition: all 0.3s;
    margin: 0; /* Убираем лишние отступы */
}

.theme-toggle:hover {
    background-color: var(--accent);
    color: white;
}

.topic-section {
    margin-bottom: 40px;
    background: var(--bg-secondary);
    border-radius: 10px;
    padding: 20px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    transition: background 0.3s;
}

.topic-title {
    font-size: 1.4em;
    color: var(--text-secondary);
    margin-bottom: 15px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--border);
    transition: color 0.3s, border-color 0.3s;
}

.qa-block {
    margin-bottom: 15px;
}

.question {
    font-weight: 600;
    font-size: 1.1em;
    cursor: pointer;
    color: var(--accent);
    padding: 10px;
    background-color: var(--qa-bg);
    border-radius: 6px;
    user-select: none;
    transition: background 0.2s;
}

.question:hover {
    background-color: var(--qa-hover);
}

.question::after {
    content: " ▶";
    float: right;
    transition: transform 0.2s;
}

.question.open::after {
    transform: rotate(90deg);
}

.answer {
    margin-top: 10px;
    padding: 15px;
    background-color: var(--answer-bg);
    border-left: 4px solid var(--accent);
    border-radius: 0 6px 6px 0;
    display: none;
    line-height: 1.6;
    font-size: 0.95em;
    transition: background 0.3s;
}

.answer.show {
    display: block;
}

.answer code {
    background: rgba(0,0,0,0.05);
    padding: 2px 6px;
    border-radius: 4px;
    font-family: monospace;
}

[data-theme="dark"] .answer code {
    background: rgba(255,255,255,0.1);
}

.btn {
    display: inline-block;
    padding: 10px 20px;
    background-color: var(--accent);
    color: white;
    text-decoration: none;
    border-radius: 6px;
    font-weight: 500;
    transition: background-color 0.2s;
    margin: 10px 0;
}

.btn:hover {
    background-color: #2980a9;
}

/* Кнопка переключения темы — улучшенный вид в тёмной теме */
[data-theme="dark"] .theme-toggle {
    background-color: #2d3748;
    border-color: #4a5568;
    color: #e2e8f0;
}

[data-theme="dark"] .theme-toggle:hover {
    background-color: #4a5568;
    color: white;
}

/* Кнопка "Показать решение" — улучшенный стиль */
.answer button {
    display: block;
    margin: 15px auto 10px;
    background-color: var(--accent);
    color: white;
    border: none;
    padding: 8px 16px;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 500;
    transition: all 0.2s ease;
}

.answer button:hover {
    background-color: #2980a9;
}

/* Для тёмной темы — более контрастный hover */
[data-theme="dark"] .answer button {
    background-color: #3182ce;
    color: white;
}

[data-theme="dark"] .answer button:hover {
    background-color: #2b6cb0;
    box-shadow: 0 2px 8px rgba(0,0,0,0.3);
}

.footer {
    margin-top: 50px;
    width: 100%;
}

.footer-inner {
    text-align: center;
}

.footer a {
    display: inline-block;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9em;
    padding: 8px 16px;
    border-radius: 20px;
    background-color: var(--bg-secondary);
    transition: all 0.2s;
}

.footer a:hover {
    background-color: var(--accent);
    color: white;
}