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

:root {
    --bg: #f5f5f5;
    --surface: #ffffff;
    --text: #333333;
    --text-secondary: #7f8c8d;
    --border: #e0e0e0;
    --hover-bg: #f8f9fa;
    --accent: #3498db;
    --accent-hover: #2980b9;
    --secondary: #95a5a6;
    --secondary-hover: #7f8c8d;
    --correct-bg: #d4edda;
    --correct-border: #c3e6cb;
    --correct-text: #155724;
    --incorrect-bg: #f8d7da;
    --incorrect-border: #f5c6cb;
    --incorrect-text: #721c24;
    --heading: #2c3e50;
    --summary-bg: #f8f9fa;
    --summary-hover: #e9ecef;
}

[data-theme="dark"] {
    --bg: #000000;
    --surface: #000000;
    --text: #e0e0e0;
    --text-secondary: #888888;
    --border: #222222;
    --hover-bg: #111111;
    --accent: #4da6ff;
    --accent-hover: #3399ff;
    --secondary: #333333;
    --secondary-hover: #444444;
    --correct-bg: #0a2e0a;
    --correct-border: #1a5c1a;
    --correct-text: #4caf50;
    --incorrect-bg: #2e0a0a;
    --incorrect-border: #5c1a1a;
    --incorrect-text: #f44336;
    --heading: #ffffff;
    --summary-bg: #111111;
    --summary-hover: #1a1a1a;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    padding: 20px;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    background: var(--surface);
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    padding: 30px;
}

header {
    border-bottom: 2px solid var(--border);
    padding-bottom: 20px;
    margin-bottom: 30px;
}

h1 {
    font-size: 28px;
    color: var(--heading);
    margin-bottom: 15px;
}

.header-controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 20px;
}

.test-selector {
    padding: 8px 12px;
    border: 2px solid var(--border);
    border-radius: 6px;
    font-size: 14px;
    background: var(--surface);
    color: var(--text);
    cursor: pointer;
}

.test-selector:hover {
    border-color: var(--accent);
}

.progress {
    font-size: 14px;
    color: var(--text-secondary);
}

.btn-icon {
    background: var(--secondary);
    color: white;
    padding: 8px 12px;
    font-size: 18px;
    line-height: 1;
}

.btn-icon:hover {
    background: var(--secondary-hover);
}

.question-header {
    margin-bottom: 20px;
}

.question-num {
    display: inline-block;
    background: var(--accent);
    color: white;
    padding: 5px 15px;
    border-radius: 20px;
    font-size: 14px;
    font-weight: 600;
}

.question-text {
    font-size: 18px;
    margin-bottom: 25px;
    color: var(--heading);
    line-height: 1.8;
}

.options {
    margin-bottom: 30px;
}

.option {
    display: flex;
    align-items: flex-start;
    padding: 15px;
    margin-bottom: 10px;
    border: 2px solid var(--border);
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s;
}

.option:hover {
    border-color: var(--accent);
    background: var(--hover-bg);
}

.option input[type="radio"],
.option input[type="checkbox"] {
    margin-right: 12px;
    margin-top: 3px;
    cursor: pointer;
}

.option label {
    flex: 1;
    cursor: pointer;
    line-height: 1.6;
}

.option.correct {
    border-color: var(--correct-border);
    background: var(--correct-bg);
}

.option.incorrect {
    border-color: var(--incorrect-border);
    background: var(--incorrect-bg);
}

.actions {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 6px;
    font-size: 16px;
    cursor: pointer;
    transition: all 0.2s;
    font-weight: 500;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-primary {
    background: var(--accent);
    color: white;
}

.btn-primary:hover:not(:disabled) {
    background: var(--accent-hover);
}

.btn-secondary {
    background: var(--secondary);
    color: white;
}

.btn-secondary:hover:not(:disabled) {
    background: var(--secondary-hover);
}

.feedback {
    padding: 15px;
    border-radius: 6px;
    margin-bottom: 20px;
    font-weight: 500;
}

.feedback.correct {
    background: var(--correct-bg);
    color: var(--correct-text);
    border: 1px solid var(--correct-border);
}

.feedback.incorrect {
    background: var(--incorrect-bg);
    color: var(--incorrect-text);
    border: 1px solid var(--incorrect-border);
}

.explanation-section {
    margin-top: 20px;
}

.collapsible {
    margin-bottom: 10px;
    border: 1px solid var(--border);
    border-radius: 6px;
    overflow: hidden;
}

.collapsible summary {
    padding: 12px 15px;
    background: var(--summary-bg);
    cursor: pointer;
    font-weight: 600;
    color: var(--heading);
    user-select: none;
}

.collapsible summary:hover {
    background: var(--summary-hover);
}

.collapsible .content {
    padding: 15px;
    line-height: 1.8;
}

.collapsible .content p {
    margin-bottom: 10px;
}

.collapsible .content ul {
    margin-left: 20px;
    margin-bottom: 10px;
}

.collapsible .content li {
    margin-bottom: 5px;
}

.collapsible .content a {
    color: var(--accent);
    text-decoration: none;
}

.collapsible .content a:hover {
    text-decoration: underline;
}

.navigation {
    display: flex;
    justify-content: space-between;
    margin-top: 30px;
    padding-top: 20px;
    border-top: 2px solid var(--border);
}

.hidden {
    display: none;
}

.docs-panel {
    position: fixed;
    top: 0;
    right: -600px;
    width: 600px;
    height: 100vh;
    background: var(--surface);
    box-shadow: -2px 0 10px rgba(0, 0, 0, 0.2);
    transition: right 0.3s ease;
    z-index: 1000;
    display: flex;
    flex-direction: column;
}

.docs-panel.open {
    right: 0;
}

.docs-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px;
    border-bottom: 2px solid var(--border);
}

.docs-header h2 {
    font-size: 24px;
    color: var(--heading);
    margin: 0;
}

.docs-controls {
    padding: 15px 20px;
    border-bottom: 1px solid var(--border);
}

.docs-content {
    flex: 1;
    overflow-y: auto;
    padding: 20px;
    line-height: 1.8;
}

.docs-content h1 {
    font-size: 28px;
    color: var(--heading);
    margin: 20px 0 15px 0;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--border);
}

.docs-content h2 {
    font-size: 22px;
    color: var(--heading);
    margin: 25px 0 12px 0;
}

.docs-content h3 {
    font-size: 18px;
    color: var(--heading);
    margin: 20px 0 10px 0;
}

.docs-content p {
    margin: 12px 0;
    color: var(--text);
}

.docs-content ul, .docs-content ol {
    margin: 12px 0;
    padding-left: 30px;
}

.docs-content li {
    margin: 8px 0;
    color: var(--text);
}

.docs-content strong {
    color: var(--heading);
    font-weight: 600;
}

.docs-content a {
    color: var(--accent);
    text-decoration: none;
}

.docs-content a:hover {
    text-decoration: underline;
}

.docs-content code {
    background: var(--hover-bg);
    padding: 2px 6px;
    border-radius: 3px;
    font-family: 'Courier New', monospace;
    font-size: 14px;
}

.docs-content pre {
    background: var(--hover-bg);
    padding: 15px;
    border-radius: 6px;
    overflow-x: auto;
    margin: 15px 0;
}

.docs-content pre code {
    background: none;
    padding: 0;
}

.docs-content blockquote {
    border-left: 4px solid var(--accent);
    margin: 15px 0;
    padding: 10px 15px;
    background: var(--hover-bg);
    border-radius: 0 6px 6px 0;
}

.docs-content blockquote p {
    margin: 5px 0;
}

.docs-content .admonition {
    border-left: 4px solid;
    margin: 15px 0;
    padding: 12px 15px;
    border-radius: 0 6px 6px 0;
}

.docs-content .admonition.note {
    border-color: #3498db;
    background: rgba(52, 152, 219, 0.1);
}

.docs-content .admonition.important {
    border-color: #e67e22;
    background: rgba(230, 126, 34, 0.1);
}

.docs-content .admonition.caution {
    border-color: #e74c3c;
    background: rgba(231, 76, 60, 0.1);
}

@media (max-width: 768px) {
    .container {
        padding: 20px;
    }

    h1 {
        font-size: 24px;
    }

    .question-text {
        font-size: 16px;
    }

    .actions {
        flex-direction: column;
    }

    .btn {
        width: 100%;
    }

    .docs-panel {
        width: 100%;
        right: -100%;
    }
}