/* General layout */
:root {
    --color-deep-purple: #15214b;
    --color-deep-green: #9eff66;
    --color-text: #333;
    --color-light-bg: #f8f9fa;
    --container-width: 1200px;
}

body {
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: var(--color-text);
}

.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 1rem;
}

/* Header styles */
.site-header {
    background-color: var(--color-deep-purple);
    padding: 1rem 0;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.header-container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 1rem;
}

.site-title {
    font-size: 2rem;
    font-weight: 700;
    color: #ffffff;
    margin: 0;
}

.domain-extension {
    color: var(--color-deep-green);
}

/* Breadcrumb styles */
.breadcrumb {
    background-color: var(--color-light-bg);
    padding: 0.8rem 0;
    border-bottom: 1px solid #dee2e6;
}

.breadcrumb ul {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    align-items: center;
}

.breadcrumb li {
    display: flex;
    align-items: center;
}

.breadcrumb li:not(:last-child)::after {
    content: "›";
    margin: 0 0.5rem;
    color: #6c757d;
}

.breadcrumb a {
    color: var(--color-deep-purple);
    text-decoration: none;
}

.breadcrumb a:hover {
    text-decoration: underline;
}

/* Main content layout */
.main-content {
    padding: 2rem 0;
}

.content-wrapper {
    display: grid;
    grid-template-columns: 250px 1fr;
    gap: 2rem;
    margin-top: 2rem;
}

/* Page outline styles */
.page-outline {
    background-color: var(--color-light-bg);
    padding: 1.5rem;
    border-radius: 8px;
    margin-bottom: 2rem;
}

.page-outline h2 {
    margin-top: 0;
    font-size: 1.25rem;
    color: var(--color-deep-purple);
}

.page-outline ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.page-outline li {
    margin: 0.5rem 0;
}

.page-outline a {
    color: var(--color-text);
    text-decoration: none;
}

.page-outline a:hover {
    color: var(--color-deep-purple);
}

/* Sidebar styles */
.sidebar {
    position: sticky;
    top: 2rem;
    align-self: start;
}

.side-navigation {
    background-color: var(--color-light-bg);
    padding: 1.5rem;
    border-radius: 8px;
}

.side-navigation h3 {
    margin-top: 0;
    color: var(--color-deep-purple);
    font-size: 1.25rem;
}

.side-navigation ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.side-navigation li {
    margin: 0.8rem 0;
}

.side-navigation a {
    color: var(--color-text);
    text-decoration: none;
    display: block;
    padding: 0.5rem;
    border-radius: 4px;
    transition: background-color 0.3s ease;
}

.side-navigation li.active a,
.side-navigation a:hover {
    background-color: rgba(21, 33, 75, 0.1);
    color: var(--color-deep-purple);
}

/* Main article styles */
.main-article {
    min-width: 0;
}

.content-section {
    margin-bottom: 3rem;
}

.content-section h2 {
    color: var(--color-deep-purple);
    margin-bottom: 1.5rem;
}

/* Footer styles */
.site-footer {
    background-color: var(--color-deep-purple);
    color: #ffffff;
    padding: 2rem 0;
    margin-top: 4rem;
}

/* Responsive design */
@media (max-width: 768px) {
    .content-wrapper {
        grid-template-columns: 1fr;
    }

    .sidebar {
        position: static;
        margin-bottom: 2rem;
    }

    .site-title {
        font-size: 1.5rem;
    }

    .breadcrumb {
        padding: 0.5rem 0;
    }
}

/* Print styles */
@media print {
    .site-header,
    .breadcrumb,
    .page-outline,
    .sidebar,
    .site-footer {
        display: none;
    }

    .content-wrapper {
        display: block;
    }

    .main-article {
        margin: 0;
        padding: 0;
    }
}

/* Add these new styles */

/* Grammar table styles */
.grammar-table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.5rem 0;
    background: white;
}

.grammar-table th,
.grammar-table td {
    padding: 1rem;
    border: 1px solid #dee2e6;
    text-align: left;
}

.grammar-table th {
    background-color: var(--color-deep-purple);
    color: white;
}

.grammar-table tr:nth-child(even) {
    background-color: var(--color-light-bg);
}

/* Usage grid styles */
.usage-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin: 1.5rem 0;
}

.usage-card {
    background: white;
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.usage-card h4 {
    color: var(--color-deep-purple);
    margin-top: 0;
}

.example-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.example-list li {
    margin: 0.8rem 0;
    padding-left: 1.5rem;
    position: relative;
}

.example-list li::before {
    content: "→";
    position: absolute;
    left: 0;
    color: var(--color-deep-purple);
}

/* Rules table styles */
.rules-table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.5rem 0;
}

.rules-table th,
.rules-table td {
    padding: 1rem;
    border: 1px solid #dee2e6;
}

.rules-table th {
    background-color: var(--color-deep-purple);
    color: white;
}

.rules-table tr:hover {
    background-color: var(--color-light-bg);
}

/* Add these new styles */

/* Verb highlighting */
.verb {
    color: var(--color-deep-purple);
    font-weight: 600;
    padding: 0 2px;
}

.verb:hover {
    background-color: rgba(21, 33, 75, 0.1);
    border-radius: 2px;
}

/* Question types grid */
.question-types-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin: 1.5rem 0;
}

.question-type-card {
    background: white;
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

/* Example box with notes */
.with-notes .note {
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px dashed #dee2e6;
    font-style: italic;
    color: #666;
}

/* Question words table */
.question-words-table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.5rem 0;
    background: white;
}

.question-words-table th,
.question-words-table td {
    padding: 1rem;
    border: 1px solid #dee2e6;
    text-align: left;
}

.question-words-table th {
    background-color: var(--color-deep-purple);
    color: white;
}

.question-words-table tr:hover {
    background-color: var(--color-light-bg);
}

/* Negatives section specific styles */

/* Negatives grid */
.negatives-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin: 1.5rem 0;
}

.negative-card {
    background: white;
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    transition: transform 0.2s ease;
}

.negative-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.negative-card h4 {
    color: var(--color-deep-purple);
    margin-top: 0;
    border-bottom: 2px solid var(--color-deep-green);
    padding-bottom: 0.5rem;
}

/* Mistakes table styles */
.mistakes-table-container {
    overflow-x: auto;
    margin: 1.5rem 0;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.mistakes-table {
    width: 100%;
    border-collapse: collapse;
    background: white;
}

.mistakes-table th,
.mistakes-table td {
    padding: 1rem;
    border: 1px solid #dee2e6;
    text-align: left;
}

.mistakes-table th {
    background-color: var(--color-deep-purple);
    color: white;
}

.mistakes-table tr:nth-child(even) {
    background-color: var(--color-light-bg);
}

.mistakes-table td:first-child {
    color: #dc3545; /* Red color for incorrect examples */
}

.mistakes-table td:nth-child(2) {
    color: #28a745; /* Green color for correct examples */
}

/* Special note styles */
.special-note {
    background: var(--color-light-bg);
    border-radius: 8px;
    padding: 1.5rem;
    margin: 2rem 0;
    border-left: 4px solid var(--color-deep-purple);
}

.special-note h3 {
    color: var(--color-deep-purple);
    margin-top: 0;
}

.note-content {
    background: white;
    padding: 1.5rem;
    border-radius: 6px;
    margin-top: 1rem;
}

.note-content .example-list {
    margin: 1rem 0;
}

.note-content .example-list li {
    display: flex;
    align-items: center;
    margin: 0.8rem 0;
}

.note-content .example-list li::before {
    content: "→";
    margin-right: 0.5rem;
    color: var(--color-deep-purple);
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .mistakes-table-container {
        margin: 1rem -1rem;
        border-radius: 0;
    }
    
    .mistakes-table th,
    .mistakes-table td {
        padding: 0.8rem;
    }
    
    .negative-card {
        padding: 1rem;
    }
    
    .special-note {
        margin: 1.5rem -1rem;
        border-radius: 0;
    }
}

/* Print styles */
@media print {
    .negative-card {
        break-inside: avoid;
        box-shadow: none;
        border: 1px solid #dee2e6;
    }
    
    .mistakes-table-container {
        break-inside: avoid;
    }
    
    .special-note {
        break-inside: avoid;
        border: 1px solid #dee2e6;
    }
}

/* Time Expressions Section Styles */

/* Time expressions grid */
.time-expressions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin: 1.5rem 0;
}

.time-card {
    background: white;
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    transition: transform 0.2s ease;
}

.time-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.time-card h4 {
    color: var(--color-deep-purple);
    margin-top: 0;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--color-deep-green);
}

/* Frequency Scale Styles */
.frequency-scale {
    margin: 2rem 0;
}

.scale-container {
    background: white;
    border-radius: 8px;
    padding: 1rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    overflow-x: auto;
}

.frequency-table {
    width: 100%;
    border-collapse: collapse;
}

.frequency-table th,
.frequency-table td {
    padding: 1rem;
    border: 1px solid #dee2e6;
    text-align: left;
}

.frequency-table th {
    background-color: var(--color-deep-purple);
    color: white;
}

.frequency-table tr:hover {
    background-color: var(--color-light-bg);
}

.frequency-table td:nth-child(2) {
    text-align: center;
    font-weight: 500;
    color: var(--color-deep-purple);
}

/* Adverb Position Styles */
.adverb-position {
    margin: 2rem 0;
}

.rules-container {
    background: white;
    border-radius: 8px;
    padding: 1rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    overflow-x: auto;
}

.position-table {
    width: 100%;
    border-collapse: collapse;
}

.position-table th,
.position-table td {
    padding: 1rem;
    border: 1px solid #dee2e6;
    text-align: left;
}

.position-table th {
    background-color: var(--color-deep-purple);
    color: white;
}

.position-table tr:hover {
    background-color: var(--color-light-bg);
}

/* State Verbs List Styles */
.state-verbs-list {
    list-style: none;
    padding: 0;
    margin: 1rem 0;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
}

.state-verbs-list li {
    background: var(--color-light-bg);
    padding: 0.8rem 1rem;
    border-radius: 6px;
    border-left: 3px solid var(--color-deep-purple);
}

/* Responsive Adjustments */
@media (max-width: 768px) {
    .time-expressions-grid {
        grid-template-columns: 1fr;
    }

    .time-card {
        margin-bottom: 1rem;
    }

    .scale-container,
    .rules-container {
        margin: 0 -1rem;
        border-radius: 0;
    }

    .frequency-table th,
    .frequency-table td,
    .position-table th,
    .position-table td {
        padding: 0.8rem;
    }

    .state-verbs-list {
        grid-template-columns: 1fr;
    }
}

/* Print Styles */
@media print {
    .time-card,
    .scale-container,
    .rules-container {
        box-shadow: none;
        border: 1px solid #dee2e6;
    }

    .time-card:hover {
        transform: none;
    }

    .frequency-table,
    .position-table {
        break-inside: avoid;
    }

    .state-verbs-list {
        break-inside: avoid;
        display: block;
    }

    .state-verbs-list li {
        margin-bottom: 0.5rem;
        border: 1px solid #dee2e6;
    }
}

/* Future Time Section Styles */

/* Future Uses Grid */
.future-uses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin: 1.5rem 0;
}

.future-card {
    background: white;
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    transition: all 0.3s ease;
}

.future-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.future-card h4 {
    color: var(--color-deep-purple);
    margin-top: 0;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--color-deep-green);
}

/* Time Expressions Table */
.time-table-container {
    background: white;
    border-radius: 8px;
    padding: 1rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    overflow-x: auto;
    margin: 1.5rem 0;
}

.time-expressions-table {
    width: 100%;
    border-collapse: collapse;
}

.time-expressions-table th,
.time-expressions-table td {
    padding: 1rem;
    border: 1px solid #dee2e6;
    text-align: left;
}

.time-expressions-table th {
    background-color: var(--color-deep-purple);
    color: white;
    white-space: nowrap;
}

.time-expressions-table tr:hover {
    background-color: var(--color-light-bg);
}

/* Context Section */
.context-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin: 1.5rem 0;
}

.context-card {
    background: white;
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    position: relative;
    overflow: hidden;
}

.context-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: var(--color-deep-purple);
}

.context-card h4 {
    color: var(--color-deep-purple);
    margin-top: 0;
    margin-bottom: 1rem;
}

.context-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.context-list li {
    margin: 0.8rem 0;
    padding-left: 1.2rem;
    position: relative;
}

.context-list li::before {
    content: "•";
    position: absolute;
    left: 0;
    color: var(--color-deep-purple);
}

/* Special Note Styles */
.note-list {
    list-style: none;
    padding-left: 0;
}

.note-list li {
    margin: 0.5rem 0;
    padding-left: 1.5rem;
    position: relative;
}

.note-list li::before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--color-deep-purple);
}

.note-example {
    font-weight: 500;
    color: var(--color-deep-purple);
    margin: 1.5rem 0 0.5rem;
}

.comparison-list {
    list-style: none;
    padding-left: 0;
    background: var(--color-light-bg);
    border-radius: 6px;
    padding: 1rem;
}

.comparison-list li {
    margin: 0.8rem 0;
    padding-left: 1.5rem;
    position: relative;
}

.comparison-list li::before {
    content: "→";
    position: absolute;
    left: 0;
    color: var(--color-deep-purple);
}

/* Responsive Adjustments */
@media (max-width: 768px) {
    .future-uses-grid,
    .context-grid {
        grid-template-columns: 1fr;
    }

    .time-table-container {
        margin: 1rem -1rem;
        border-radius: 0;
    }

    .context-card {
        margin-bottom: 1rem;
    }

    .time-expressions-table th,
    .time-expressions-table td {
        padding: 0.8rem;
    }
}

/* Print Styles */
@media print {
    .future-card,
    .time-table-container,
    .context-card {
        box-shadow: none;
        border: 1px solid #dee2e6;
    }

    .future-card:hover {
        transform: none;
    }

    .comparison-list {
        border: 1px solid #dee2e6;
    }

    .context-card::before {
        display: none;
    }
}
/* Practice Section Styles */

/* General Practice Styles */
.practice-section {
    margin: 2.5rem 0;
}

.practice-intro {
    color: #666;
    font-style: italic;
    margin-bottom: 1.5rem;
}

.practice-box {
    background: white;
    border-radius: 8px;
    padding: 2rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    margin: 1.5rem 0;
}

/* Practice List Styles */
.practice-list {
    list-style-position: inside;
    padding: 0;
}

.practice-list li {
    margin-bottom: 1.5rem;
    padding-bottom: 1.5rem;
    border-bottom: 1px solid #dee2e6;
}

.practice-list li:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

/* Fill in the Blanks */
.fill-blanks .question {
    font-size: 1.1rem;
    color: var(--color-deep-purple);
}

.fill-blanks .answer {
    display: none;
    margin-top: 0.5rem;
    padding: 0.5rem;
    background: var(--color-light-bg);
    border-radius: 4px;
}

/* Multiple Choice */
.options {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
    margin-top: 1rem;
}

.option {
    display: flex;
    align-items: center;
    padding: 0.8rem;
    background: var(--color-light-bg);
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.2s ease;
}

.option:hover {
    background: #e9ecef;
}

.option input[type="radio"] {
    margin-right: 0.5rem;
}

.option.correct {
    border-left: 3px solid #28a745;
}

/* Error Correction */
.error-correction .incorrect {
    color: #dc3545;
    text-decoration: line-through;
    margin-bottom: 0.5rem;
}

.error-correction .correct {
    color: #28a745;
    margin-top: 0.5rem;
}

/* Sentence Formation */
.sentence-formation .scrambled {
    font-family: monospace;
    background: var(--color-light-bg);
    padding: 0.8rem;
    border-radius: 4px;
    margin-bottom: 0.5rem;
}

.sentence-formation .answer {
    display: none;
    color: var(--color-deep-purple);
    font-weight: 500;
    margin-top: 0.5rem;
}

/* Practice Section Styles */

/* Practice Container */
.practice-container {
    background: white;
    border-radius: 8px;
    margin: 1.5rem 0;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    overflow: hidden;
}

/* Practice Header */
.practice-header {
    background: var(--color-light-bg);
    padding: 1rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid #dee2e6;
    cursor: pointer;
}

.practice-header h3 {
    margin: 0;
    color: var(--color-deep-purple);
    font-size: 1.1rem;
}

/* Toggle Button */
.toggle-answer {
    background: none;
    border: none;
    color: var(--color-deep-purple);
    cursor: pointer;
    padding: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: transform 0.3s ease;
}

.toggle-answer .arrow {
    font-size: 1rem;
}

.toggle-answer:hover {
    opacity: 0.8;
}

/* Practice Section Styles */

/* Practice Container */
.practice-container {
    background: white;
    border-radius: 8px;
    margin: 2rem 0;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    overflow: hidden;
}

/* Practice Header */
.practice-header {
    background: var(--color-light-bg);
    padding: 1.2rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    border-bottom: 1px solid #dee2e6;
    transition: background-color 0.2s ease;
}

.practice-header:hover {
    background: #e9ecef;
}

.practice-header h3 {
    margin: 0;
    color: var(--color-deep-purple);
    font-size: 1.1rem;
    font-weight: 600;
}

/* Toggle Button */
.toggle-answer {
    background: none;
    border: none;
    color: var(--color-deep-purple);
    cursor: pointer;
    padding: 0.5rem;
    transition: transform 0.3s ease;
}

.toggle-answer .arrow {
    display: block;
    transition: transform 0.3s ease;
}

.practice-container.active .toggle-answer .arrow {
    transform: rotate(180deg);
}

/* Practice Content */
.practice-content {
    padding: 0;
    max-height: 0;
    overflow: hidden;
    transition: all 0.3s ease-in-out;
}

.practice-container.active .practice-content {
    padding: 1.5rem;
    max-height: 2000px; /* 增加最大高度以适应更多内容 */
}

/* Question Section */
.question-section {
    margin-bottom: 2rem;
}

.instruction {
    color: #666;
    font-style: italic;
    margin-bottom: 1.5rem;
}

.practice-items {
    background: var(--color-light-bg);
    padding: 1.5rem;
    border-radius: 6px;
}

.practice-items ol {
    margin: 0;
    padding-left: 1.5rem;
}

.practice-items li {
    margin: 1rem 0;
    line-height: 1.6;
    color: #333;
}

/* Answer Section */
.answer-section {
    border-top: 2px dashed #dee2e6;
    padding-top: 1.5rem;
    margin-top: 1.5rem;
}

.answer-section h4 {
    color: var(--color-deep-purple);
    margin: 0 0 1.5rem 0;
    font-size: 1.1rem;
}

.answer-section ol {
    list-style-position: outside;
    padding-left: 1.5rem;
    margin: 0;
}

.answer-section li {
    margin-bottom: 1.5rem;
    padding-left: 0.5rem;
}

.correct-answer {
    background: rgba(40, 167, 69, 0.1);
    padding: 0.8rem 1rem;
    border-radius: 4px;
    margin-bottom: 0.5rem;
    color: #28a745;
    font-weight: 500;
}

.explanation {
    color: #666;
    font-size: 0.95rem;
    margin: 0.5rem 0 0 0;
    padding-left: 1rem;
    border-left: 3px solid var(--color-deep-purple);
}

/* Verb Highlighting */
.verb {
    color: var(--color-deep-purple);
    font-weight: 600;
    padding: 0 2px;
}

/* Responsive Adjustments */
@media (max-width: 768px) {
    .practice-container {
        margin: 1.5rem -1rem;
        border-radius: 0;
    }

    .practice-header {
        padding: 1rem;
    }

    .practice-container.active .practice-content {
        padding: 1rem;
    }

    .practice-items {
        padding: 1rem;
    }

    .practice-items ol {
        padding-left: 1.2rem;
    }

    .answer-section ol {
        padding-left: 1.2rem;
    }

    .correct-answer {
        padding: 0.6rem 0.8rem;
    }
}

/* Print Styles */
@media print {
    .practice-container {
        margin: 1rem 0;
        break-inside: avoid;
        box-shadow: none;
        border: 1px solid #dee2e6;
    }

    .practice-content {
        max-height: none !important;
        padding: 1.5rem !important;
    }

    .toggle-answer {
        display: none;
    }

    .practice-header {
        background: none;
    }

    .correct-answer {
        border: 1px solid #28a745;
        background: none;
    }

    .explanation {
        border-left-color: #666;
    }
}

/* Outline Navigation Styles */
.outline-nav {
    position: sticky;
    top: 0;
    z-index: 100;
    background: white;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    transition: all 0.3s ease;
}

.outline-nav.collapsed {
    max-height: 60px; /* 折叠时只显示标题 */
    overflow: hidden;
}

.outline-nav:hover,
.outline-nav.expanded {
    max-height: 500px; /* 展开时的最大高度 */
}

.outline-header {
    padding: 1rem 1.5rem;
    background: var(--color-deep-purple);
    color: white;
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
}

.outline-header h2 {
    margin: 0;
    font-size: 1.2rem;
}

.outline-toggle {
    background: none;
    border: none;
    color: white;
    cursor: pointer;
    padding: 0.5rem;
}

.outline-content {
    padding: 1rem 1.5rem;
    background: white;
}

.outline-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.outline-list li {
    margin: 0.8rem 0;
}

.outline-list a {
    color: var(--color-deep-purple);
    text-decoration: none;
    display: block;
    padding: 0.5rem;
    border-radius: 4px;
    transition: background-color 0.2s ease;
}

.outline-list a:hover,
.outline-list a.active {
    background: var(--color-light-bg);
}

/* Responsive Adjustments */
@media (max-width: 768px) {
    .outline-nav {
        position: fixed;
        width: 100%;
    }

    .outline-header {
        padding: 0.8rem 1rem;
    }

    .outline-content {
        padding: 0.8rem 1rem;
    }
}