:root {
    --bg-color: #f5f5f5;
    --card-bg: #ffffff;
    --text-color: #000000;
    --secondary-text: #707579;
    --accent-color: #3390ec;
    --button-text: #ffffff;
    --border-color: #e0e0e0;
}

[data-theme="dark"] {
    --bg-color: #17212b;
    --card-bg: #242f3d;
    --text-color: #ffffff;
    --secondary-text: #7f8b96;
    --accent-color: #5288c1;
    --button-text: #ffffff;
    --border-color: #2b384d;
}

body {
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.2s ease, color 0.2s ease;
}

.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px 16px;
    background: var(--card-bg);
    box-shadow: 0 1px 2px rgba(0,0,0,0.1);
}

.icon-btn {
    background: none;
    border: none;
    color: var(--secondary-text);
    cursor: pointer;
    padding: 8px;
    border-radius: 50%;
}

.icon-btn:hover {
    background-color: rgba(0,0,0,0.05);
}

.screen {
    padding: 16px;
    display: none;
}

.hidden {
    display: none !important;
}

.screen.active {
    display: block;
}

.card {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 16px;
    margin-bottom: 16px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.05);
}

.menu-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 20px;
    cursor: pointer;
    width: 100%;
    color: var(--text-color);
}

.grid-menu {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

.back-btn {
    display: block;
    width: 100%;
    margin-top: 16px;
    padding: 12px;
    background: var(--secondary-text);
    border: none;
    border-radius: 8px;
    color: #ffffff;
    cursor: pointer;
    font-size: 16px;
    font-weight: 500;
}

.back-btn:hover {
    opacity: 0.85;
}

.answers {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.answer-btn {
    padding: 12px 16px;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-color);
    cursor: pointer;
    text-align: left;
    font-size: 15px;
}

.answer-btn:hover {
    background-color: rgba(51, 144, 236, 0.1);
    border-color: var(--accent-color);
}

.answer-btn.correct {
    background-color: #4caf50;
    color: white;
    border-color: #4caf50;
}

.answer-btn.wrong {
    background-color: #f44336;
    color: white;
    border-color: #f44336;
}

.answer-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

.answers {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.quiz-header {
    background: var(--card-bg);
    padding: 16px;
    border-radius: 12px;
    margin-bottom: 16px;
}

.question-card {
    background: var(--card-bg);
    padding: 16px;
    border-radius: 12px;
    margin-bottom: 16px;
}

.question-card img {
    width: 100%;
    border-radius: 8px;
    margin-bottom: 12px;
}

.explanation {
    background: #fff3cd;
    border-left: 4px solid #ffc107;
    padding: 12px;
    border-radius: 8px;
    margin-top: 16px;
    color: #856404;
}

[data-theme="dark"] .explanation {
    background: #3d3416;
    color: #ffc107;
}

.result-message {
    padding: 12px;
    border-radius: 8px;
    margin-top: 16px;
    font-weight: 500;
}

.result-message.correct {
    background: #d4edda;
    color: #155724;
    border-left: 4px solid #28a745;
}

.result-message.wrong {
    background: #f8d7da;
    color: #721c24;
    border-left: 4px solid #dc3545;
}

[data-theme="dark"] .result-message.correct {
    background: #1e3a25;
    color: #4caf50;
}

[data-theme="dark"] .result-message.wrong {
    background: #3a1e1e;
    color: #f44336;
}

.next-question-btn {
    width: 100%;
    padding: 14px;
    background: var(--accent-color);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    margin-top: 16px;
}

.next-question-btn:hover {
    opacity: 0.9;
}

.quiz-controls {
    display: flex;
    flex-direction: column;
    gap: 12px;
    margin-top: 16px;
}

.quiz-controls .back-btn {
    margin-top: 0;
}

/* Profile Stats */
.stat-item {
    padding: 15px;
    background: var(--bg-color);
    border-radius: 8px;
    text-align: center;
}

.stat-label {
    font-size: 14px;
    color: var(--secondary-text);
    margin-bottom: 8px;
}

.stat-value {
    font-size: 28px;
    font-weight: bold;
    color: var(--text-color);
}

/* Theme Icons Toggle */
.sun-icon { display: none; }
.moon-icon { display: block; }

[data-theme="dark"] .sun-icon { display: block; }
[data-theme="dark"] .moon-icon { display: none; }