/* CSS 변수 정의 */
:root {
    /* 색상 변수 */
    --primary-color: #667eea;
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --primary-gradient-180: linear-gradient(180deg, #667eea 0%, #764ba2 100%);
    --secondary-color: #f5f7fa;
    --text-color: #333;
    --text-muted: #666;
    --text-light: #777;
    --border-color: #e0e0e0;
    --border-color-light: #ddd;
    --border-color-lighter: #e9ecef;
    --background-white: white;
    --background-light: #f8f9fa;
    --background-lighter: #f1f3f4;
    
    /* 그림자 */
    --shadow: 0 2px 10px rgba(0,0,0,0.1);
    --shadow-light: 0 2px 4px rgba(0,0,0,0.1);
    --shadow-hover: 0 4px 15px rgba(0,0,0,0.15);
    --shadow-large: 0 4px 20px rgba(0,0,0,0.1);
    
    /* 테두리 반지름 */
    --border-radius: 5px;
    --border-radius-md: 8px;
    --border-radius-large: 10px;
    --border-radius-xl: 12px;
    --border-radius-pill: 20px;
    --border-radius-circle: 50%;
    
    /* 간격 */
    --spacing-xs: 5px;
    --spacing-sm: 10px;
    --spacing-md: 15px;
    --spacing-lg: 20px;
    --spacing-xl: 30px;
    
    /* 폰트 크기 */
    --font-size-xs: 0.8em;
    --font-size-sm: 0.9em;
    --font-size-base: 1em;
    --font-size-lg: 1.1em;
    --font-size-xl: 1.2em;
    --font-size-2xl: 1.3em;
    --font-size-3xl: 1.4em;
    --font-size-4xl: 1.8em;
    --font-size-5xl: 2em;
    --font-size-6xl: 2.5em;
    
    /* 폰트 패밀리 */
    --font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    --font-family-mono: 'Courier New', monospace;
    
    /* 전환 효과 */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
    
    /* 상태 색상 */
    --success-color: #28a745;
    --warning-color: #ffc107;
    --danger-color: #dc3545;
    --info-color: #007bff;
    
    /* 네트워크 관련 색상 */
    --network-broader: #007bff;
    --network-narrower: #28a745;
    --network-related: #ffc107;
    --network-cosine: #6c757d;
    --network-generated: #17a2b8;
}

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

body {
    font-family: var(--font-family);
    background-color: var(--secondary-color);
    color: var(--text-color);
    line-height: 1.6;
}

/* 공통 유틸리티 클래스 */
.btn {
    padding: 12px 24px;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: var(--font-size-base);
    transition: all var(--transition-normal);
    text-decoration: none;
    display: inline-block;
    font-weight: 500;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

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

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

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

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none !important;
}

.card {
    background: var(--background-white);
    border-radius: var(--border-radius-large);
    box-shadow: var(--shadow);
    padding: var(--spacing-xl);
}

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

.text-muted {
    color: var(--text-muted);
}

.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.mb-xl { margin-bottom: var(--spacing-xl); }

.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }

/* 앱 컨테이너 */
.app-container {
    display: flex;
    min-height: 100vh;
}

/* 사이드바 */
.sidebar {
    width: 250px;
    background: var(--primary-gradient-180);
    color: var(--background-white);
    position: fixed;
    height: 100vh;
    left: 0;
    top: 0;
    z-index: 1000;
    box-shadow: 2px 0 10px rgba(0,0,0,0.1);
}

.sidebar-header {
    padding: var(--spacing-lg);
    border-bottom: 1px solid rgba(255,255,255,0.1);
}

.sidebar-header h2 {
    font-size: var(--font-size-3xl);
    font-weight: 600;
}

.sidebar-menu {
    list-style: none;
    padding: var(--spacing-lg) 0;
}

.menu-item {
    display: flex;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-lg);
    cursor: pointer;
    transition: all var(--transition-normal);
    border-left: 3px solid transparent;
}

.menu-item:hover {
    background-color: rgba(255,255,255,0.1);
}

.menu-item.active {
    background-color: rgba(255,255,255,0.2);
    border-left-color: var(--background-white);
}

.menu-icon {
    font-size: var(--font-size-xl);
    margin-right: 12px;
    min-width: 20px;
}

.menu-text {
    font-size: var(--font-size-base);
    font-weight: 500;
}

/* 메인 콘텐츠 */
.main-content {
    flex: 1;
    margin-left: 250px;
    padding: var(--spacing-xl);
    background-color: var(--secondary-color);
    min-height: 100vh;
    overflow-y: auto;
}

.content-section {
    display: none;
}

.content-section.active {
    display: block;
}

.content-header {
    text-align: center;
    margin-bottom: var(--spacing-xs);
    padding: var(--spacing-lg) 0;
}

.content-header h1 {
    font-size: var(--font-size-6xl);
    margin-bottom: var(--spacing-sm);
    color: var(--text-color);
}

.content-header p {
    font-size: var(--font-size-lg);
    color: var(--text-muted);
}

/* 로딩 스피너 스타일 */
.loading {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 40px;
    text-align: center;
}

.loading-spinner {
    display: inline-block;
    width: 40px;
    height: 40px;
    border: 4px solid #f3f3f3;
    border-top: 4px solid var(--info-color);
    border-radius: var(--border-radius-circle);
    animation: spin 1s linear infinite;
    margin-right: var(--spacing-sm);
}

/* 바람개비 애니메이션 */
@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* 준비 중 페이지 스타일 */
.coming-soon {
    text-align: center;
    padding: 80px var(--spacing-lg);
    background: var(--background-white);
    border-radius: var(--border-radius-large);
    box-shadow: var(--shadow);
    max-width: 600px;
    margin: 0 auto;
}

.coming-soon-icon {
    font-size: 4em;
    margin-bottom: var(--spacing-lg);
}

.coming-soon h2 {
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
    font-size: var(--font-size-4xl);
}

.coming-soon p {
    color: var(--text-muted);
    font-size: var(--font-size-lg);
    line-height: 1.6;
}

/* 검색 섹션 */
.search-section {
    background: var(--background-white);
    padding: var(--spacing-xl);
    border-radius: var(--border-radius-large);
    box-shadow: var(--shadow);
    margin-bottom: var(--spacing-xl);
}

.search-tabs {
    display: flex;
    margin-bottom: var(--spacing-lg);
    border-bottom: 2px solid #eee;
}

.tab-button {
    background: none;
    border: none;
    padding: var(--spacing-sm) var(--spacing-lg);
    cursor: pointer;
    font-size: var(--font-size-base);
    color: var(--text-muted);
    border-bottom: 2px solid transparent;
    transition: all var(--transition-normal);
}

.tab-button.active {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

.tab-button:hover {
    color: var(--primary-color);
}

.search-form {
    display: none;
}

.search-form.active {
    display: block;
}

.search-input-group {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
}

.search-input-group input {
    flex: 1;
    padding: 12px;
    border: 2px solid var(--border-color-light);
    border-radius: var(--border-radius);
    font-size: var(--font-size-base);
}

.search-input-group input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.search-input-group button,
.search-form > button {
    padding: 12px 24px;
    background: var(--primary-gradient);
    color: var(--background-white);
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: var(--font-size-base);
    transition: transform var(--transition-fast);
}

.search-input-group button:hover,
.search-form > button:hover {
    transform: translateY(-2px);
}

.search-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-bottom: 20px;
}

.search-field label {
    display: block;
    margin-bottom: 5px;
    font-weight: bold;
    color: #555;
}

.search-field input {
    width: 100%;
    padding: 10px;
    border: 2px solid #ddd;
    border-radius: 5px;
    font-size: 1em;
}

.search-field input:focus {
    outline: none;
    border-color: #667eea;
}

/* 검색 옵션 스타일 */
.search-options {
    display: flex;
    gap: 20px;
    align-items: center;
    margin-top: 15px;
    padding: 15px;
    background-color: #f8f9fa;
    border-radius: 5px;
    flex-wrap: wrap;
}

.option-group {
    display: flex;
    align-items: center;
    gap: 10px;
}

.search-options label {
    font-weight: bold;
    color: #555;
    white-space: nowrap;
}

.search-options input[type="range"] {
    width: 100px;
}

.search-options select {
    padding: 5px 10px;
    border: 1px solid #ddd;
    border-radius: 3px;
    background-color: white;
    font-size: 1em;
}

#network-threshold-value {
    font-weight: bold;
    color: #667eea;
    min-width: 30px;
}

/* 반응형 디자인 */
@media (max-width: 768px) {
    .sidebar {
        width: 200px;
    }
    
    .main-content {
        margin-left: 200px;
        padding: 20px 15px;
    }
    
    .sidebar-header h2 {
        font-size: 1.2em;
    }
    
    .menu-item {
        padding: 12px 15px;
    }
    
    .menu-text {
        font-size: 0.9em;
    }
    
    .content-header h1 {
        font-size: 2em;
    }
    
    .search-tabs {
        flex-wrap: wrap;
    }
    
    .tab-button {
        flex: 1;
        min-width: 120px;
        font-size: 0.9em;
        padding: 8px 12px;
    }
    
    .search-options {
        flex-direction: column;
        align-items: stretch;
        gap: 10px;
    }
    
    .option-group {
        justify-content: space-between;
    }
    
    .search-input-group {
        flex-direction: column;
    }
    
    .search-grid {
        grid-template-columns: 1fr;
    }
    
    .book-meta {
        flex-direction: column;
        gap: 8px;
    }
    
    .modal-content {
        margin: 10% auto;
        width: 95%;
        padding: 20px;
    }
}

@media (max-width: 480px) {
    .sidebar {
        width: 60px;
    }
    
    .main-content {
        margin-left: 60px;
        padding: 15px 10px;
    }
    
    .sidebar-header {
        padding: 15px 10px;
    }
    
    .sidebar-header h2 {
        display: none;
    }
    
    .menu-item {
        padding: 15px 10px;
        justify-content: center;
    }
    
    .menu-text {
        display: none;
    }
    
    .menu-icon {
        margin-right: 0;
        text-align: center;
    }
    
    .content-header h1 {
        font-size: 1.8em;
    }
    
    .content-header p {
        font-size: 1em;
    }
    
    .tab-button {
        font-size: 0.8em;
        padding: 6px 8px;
        min-width: 100px;
    }
}

/* 결과 섹션 */
.results-section {
    background: white;
    padding: 30px;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.search-info {
    margin-bottom: 20px;
    padding: 15px;
    background: #f8f9fa;
    border-radius: 5px;
    color: #666;
}

.loading {
    text-align: center;
    padding: 40px;
    font-size: 1.2em;
    color: #667eea;
    display: none;
}

/* 주제 세부 정보 */
.subject-detail-meta {
    margin-bottom: 10px;
}

/* 공통 결과 아이템 스타일 */
.result-item, .book-item, .subject-item {
    background: white;
    border: 1px solid #e0e0e0;
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 15px;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.result-item:hover, .book-item:hover, .subject-item:hover {
    background: #f8f9fa;
    border-color: #007bff;
    box-shadow: 0 4px 8px rgba(0,0,0,0.15);
    transform: translateY(-2px);
}

/* 공통 제목 스타일 */
.result-title, .book-title, .subject-title {
    font-size: 1.3em;
    font-weight: 600;
    color: #333;
    margin-bottom: 10px;
    line-height: 1.4;
}

/* 공통 메타 정보 스타일 */
.result-meta, .book-meta, .subject-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
    margin-bottom: 10px;
    color: #666;
    font-size: 14px;
}

.result-meta span, .book-meta span, .subject-meta span {
    background: #f1f3f4;
    padding: 4px 8px;
    border-radius: 4px;
    font-size: 0.9em;
}

/* 공통 본문 스타일 */
.result-content, .book-intro, .subject-definition {
    color: #777;
    font-size: 0.95em;
    line-height: 1.5;
    max-height: 60px;
    overflow: hidden;
    margin-top: 10px;
}

/* 페이지네이션 */
.pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 10px;
    margin-top: 30px;
}

.pagination button {
    padding: 8px 12px;
    border: 1px solid #ddd;
    background: white;
    cursor: pointer;
    border-radius: 4px;
    transition: all 0.3s;
}

.pagination button:hover {
    background: #f5f5f5;
}

.pagination button.active {
    background: #667eea;
    color: white;
    border-color: #667eea;
}

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

/* 모달 */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
}

.modal-content {
    background-color: var(--background-white);
    margin: 5% auto;
    padding: var(--spacing-xl);
    border-radius: var(--border-radius-large);
    width: 90%;
    max-width: 800px;
    max-height: 80vh;
    overflow-y: auto;
    position: relative;
}

.close {
    position: absolute;
    right: var(--spacing-lg);
    top: var(--spacing-md);
    font-size: 28px;
    font-weight: bold;
    cursor: pointer;
    color: #aaa;
    transition: color var(--transition-normal);
}

.close:hover {
    color: var(--primary-color);
}

/* 주제 탐색 모달 스타일 */
.subject-explore-modal .modal-content {
    max-width: 900px;
}

.subject-explore-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 2px solid var(--border-color);
}

.subject-explore-title {
    color: #2c3e50;
    margin: 0;
}

.subject-id-badge {
    background-color: #3498db;
    color: var(--background-white);
    padding: 4px 8px;
    border-radius: 4px;
    font-size: var(--font-size-xs);
}

.subject-detail-title {
    text-align: center;
    margin-bottom: 20px;
    color: #333;
    font-size: 1.8em;
}

.subject-detail-section {
    margin-bottom: 25px;
}

.subject-detail-section h3 {
    color: #2c3e50;
    margin-bottom: 15px;
    border-bottom: 1px solid #eee;
    padding-bottom: 5px;
}

.relations-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.relation-item {
    padding: 12px;
    border: 1px solid #ddd;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
    background: #f9f9f9;
}

.relation-item:hover {
    background: #f0f8ff;
    transform: translateY(-1px);
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.relation-header {
    display: flex;
    align-items: center;
    gap: 10px;
}

.relation-type-badge {
    padding: 4px 8px;
    border-radius: 4px;
    font-size: 0.75em;
    font-weight: bold;
    color: white;
}

.relation-type-badge.broader {
    background-color: #e74c3c;
}

.relation-type-badge.narrower {
    background-color: #27ae60;
}

.relation-type-badge.related {
    background-color: #3498db;
}

.relation-type-badge.equivalent {
    background-color: #9b59b6;
}

.relation-target {
    flex: 1;
    font-weight: 500;
}

.metadata-info {
    color: #666;
    font-size: 0.9em;
}

.relation-meta {
    margin-top: 5px;
}

.relation-meta small {
    color: #888;
}

.modal-actions {
    margin-top: 30px;
    text-align: center;
}

.btn-primary {
    background-color: #3498db;
    color: white;
    padding: 10px 20px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 16px;
    transition: background-color 0.2s ease;
}

.btn-primary:hover {
    background-color: #2980b9;
}

.close:hover {
    color: #667eea;
}

.book-detail-title {
    font-size: 1.8em;
    color: #333;
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 2px solid #eee;
}

.book-detail-section {
    margin-bottom: 20px;
}

.book-detail-section h3 {
    color: #667eea;
    margin-bottom: 10px;
    font-size: 1.2em;
}

.book-detail-section p {
    line-height: 1.6;
    color: #555;
}

.book-detail-meta {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
    margin-bottom: 20px;
}

.meta-item {
    background: #f8f9fa;
    padding: 5px;
    border-radius: 5px;
}

/* NLK Subjects 스타일 */
.nlk-subjects-list {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.nlk-subject-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 8px 12px;
    background: #f0f4ff;
    border: 1px solid #e0e8ff;
    border-radius: 6px;
    transition: all 0.2s ease;
}

.nlk-subject-item:hover {
    background: #e6f0ff;
}

/* 클릭 가능한 주제 아이템 스타일 */
.clickable-subject {
    cursor: pointer;
}

.clickable-subject:hover {
    background-color: #e3f2fd !important;
    transform: translateY(-1px);
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.clickable-subject:active {
    transform: translateY(0);
}

.subject-label {
    flex: 1;
    font-weight: 500;
    color: #333;
}

.subject-type {
    background: #667eea;
    color: white;
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 0.8em;
    font-weight: 600;
}

.subject-id {
    font-family: monospace;
    font-size: 0.85em;
    color: #666;
    background: #f8f9fa;
    padding: 2px 6px;
    border-radius: 3px;
}

.meta-item strong {
    color: #667eea;
}

/* 반응형 디자인 */
@media (max-width: 768px) {
    .container {
        padding: 10px;
    }
    
    header h1 {
        font-size: 2em;
    }
    
    .search-input-group {
        flex-direction: column;
    }
    
    .search-grid {
        grid-template-columns: 1fr;
    }
    
    .book-meta {
        flex-direction: column;
        gap: 8px;
    }
    .book-meta span {
        display: inline-block;
        width: fit-content;
    }
    .modal-content {
        margin: 10% auto;
        width: 95%;
        padding: 20px;
    }
}

/* 에러 메시지 */
.error-message {
    background: #fee;
    color: #c33;
    padding: var(--spacing-md);
    border-radius: var(--border-radius);
    margin: var(--spacing-lg) 0;
    border-left: 4px solid #c33;
}

/* 성공 메시지 */
.success-message {
    background: #efe;
    color: #363;
    padding: var(--spacing-md);
    border-radius: var(--border-radius);
    margin: var(--spacing-lg) 0;
    border-left: 4px solid #363;
}

/* 네트워크 시각화 스타일 */
.network-controls {
    background: white;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    margin-bottom: 20px;
}

.seed-search {
    margin-bottom: 20px;
}

.search-input-group {
    display: flex;
    gap: 10px;
    margin-bottom: 15px;
}

.search-input-group input {
    flex: 1;
    padding: 12px;
    border: 2px solid #e1e5e9;
    border-radius: 8px;
    font-size: 16px;
}

.search-input-group input:focus {
    outline: none;
    border-color: #667eea;
}

.search-input-group button {
    padding: 12px 24px;
    background: #667eea;
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-weight: 500;
    transition: background-color 0.3s;
}

.search-input-group button:hover {
    background: #5a6fd8;
}

.seed-candidates {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.seed-candidate {
    background: #f8f9fa;
    border: 2px solid #e9ecef;
    border-radius: 8px;
    padding: 10px 15px;
    cursor: pointer;
    transition: all 0.3s;
    max-width: 300px;
}

.seed-candidate:hover {
    background: #667eea;
    color: white;
    border-color: #667eea;
}

.seed-candidate-label {
    font-weight: 600;
    margin-bottom: 5px;
}

.seed-candidate-definition {
    font-size: 0.9em;
    opacity: 0.8;
    display: -webkit-box;
    -webkit-box-orient: vertical;
    -webkit-line-clamp: 3;
    line-clamp: 3;
    overflow: hidden;
}

.network-actions {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 15px;
}

#reset-network {
    padding: 10px 20px;
    background: #dc3545;
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-weight: 500;
}

#reset-network:hover {
    background: #c82333;
}

#reset-network:disabled {
    background: #6c757d;
    cursor: not-allowed;
}

.expansion-settings {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.9em;
}

.expansion-settings label {
    color: #666;
    white-space: nowrap;
}

#max-expansion-nodes {
    padding: 5px 8px;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 0.9em;
    background: white;
    cursor: pointer;
}

#max-expansion-nodes:focus {
    outline: none;
    border-color: #007bff;
    box-shadow: 0 0 0 2px rgba(0, 123, 255, 0.25);
}

.network-info {
    display: flex;
    gap: 20px;
    font-size: 0.9em;
    color: #666;
}

/* 네트워크 로딩 오버레이 */
.network-loading-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.4);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    border-radius: 8px;
}

.network-loading-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 15px;
    padding: 30px;
    background: white;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.network-loading-content .loading-spinner {
    width: 50px;
    height: 50px;
    border: 4px solid #f3f3f3;
    border-top: 4px solid #667eea;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

.network-loading-content .loading-text {
    font-size: 16px;
    color: #333;
    font-weight: 500;
    text-align: center;
}

/* 네트워크 컨테이너 상대 위치 설정 */
.network-container {
    position: relative;
    width: 100%;
    height: 600px;
    border: 2px solid #e1e5e9;
    border-radius: 8px;
    background: #f8f9fa;
    overflow: hidden;
}

#network-visualization {
    width: 100%;
    height: 100%;
}

.network-tooltip {
    position: absolute;
    background: rgba(0, 0, 0, 0.9);
    color: white;
    padding: 10px;
    border-radius: 5px;
    font-size: 12px;
    pointer-events: none;
    opacity: 0;
    transition: opacity 0.3s;
    max-width: 300px;
    z-index: 1000;
}

.network-tooltip.visible {
    opacity: 1;
}

/* D3.js 네트워크 요소 스타일 */
.node {
    cursor: pointer;
    stroke: #fff;
    stroke-width: 2px;
}

.node.current {
    fill: #667eea;
}

.node.neighbor {
    fill: #28a745;
}

.node.expanded {
    fill: #ffc107;
}

.node:hover {
    stroke-width: 3px;
}

/* 도서 노드 스타일 (사각형) */
.book-node {
    stroke: #fff;
    stroke-width: 2px;
}

.book-node.current {
    fill: #dc3545;
}

.book-node.neighbor {
    fill: #6f42c1;
}

.book-node.expanded {
    fill: #fd7e14;
}

/* 노드 컨텍스트 메뉴 */
.node-context-menu {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    box-shadow: var(--shadow-large);
    padding: 8px 0;
    min-width: 150px;
    font-size: var(--font-size-sm);
    z-index: 1000;
}

.context-menu-item {
    padding: 8px 16px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: background-color 0.2s;
}

.context-menu-item:hover {
    background-color: var(--background-lighter);
}

.menu-icon {
    font-size: 14px;
    width: 16px;
    text-align: center;
}

.menu-text {
    flex: 1;
    font-weight: 500;
}

.link {
    stroke: #999;
    stroke-opacity: 0.6;
    stroke-width: 2px;
}

.link-label {
    font-size: 10px;
    fill: #666;
    text-anchor: middle;
    pointer-events: none;
}

.node-label {
    font-size: 12px;
    fill: #333;
    text-anchor: middle;
    pointer-events: none;
    font-weight: 500;
}

/* 관련 주제 리스트 스타일 */
.relations-list {
    margin-top: var(--spacing-md);
    display: grid;
    gap: 12px;
}

.relation-item {
    background: var(--background-white);
    border: 2px solid var(--border-color-lighter);
    border-radius: var(--border-radius-xl);
    padding: 16px;
    transition: all var(--transition-normal);
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.relation-item:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow);
    border-color: var(--info-color);
}

.relation-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 8px;
    flex-wrap: wrap;
}

.relation-type-badge {
    padding: 6px 12px;
    border-radius: var(--border-radius-pill);
    font-size: 12px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    white-space: nowrap;
    flex-shrink: 0;
    color: var(--background-white);
}

/* 관계 유형별 색상 테마 */

/* 상위 주제 (broader) */
.relation-item.broader {
    border-left: 6px solid var(--network-broader);
    background: linear-gradient(135deg, #f8fff9 0%, var(--background-white) 100%);
}

.relation-type-badge.broader {
    background: var(--network-broader);
}

.relation-item.broader:hover {
    border-color: var(--network-broader);
    box-shadow: 0 4px 12px rgba(40, 167, 69, 0.2);
}

/* 하위 주제 (narrower) */
.relation-item.narrower {
    border-left: 6px solid var(--network-narrower);
    background: linear-gradient(135deg, #f8fbff 0%, var(--background-white) 100%);
}

.relation-type-badge.narrower {
    background: var(--network-narrower);
}

.relation-item.narrower:hover {
    border-color: var(--network-narrower);
    box-shadow: 0 4px 12px rgba(0, 123, 255, 0.2);
}

/* 관련 주제 (related) */
.relation-item.related {
    border-left: 6px solid var(--network-related);
    background: linear-gradient(135deg, #fffaf7 0%, var(--background-white) 100%);
}

.relation-type-badge.related {
    background: var(--network-related);
}

.relation-item.related:hover {
    border-color: var(--network-related);
    box-shadow: 0 4px 12px rgba(253, 126, 20, 0.2);
}

/* 유사 벡터 주제 (cosine_related) */
.relation-item.cosine_related {
    border-left: 6px solid var(--network-cosine);
    background: linear-gradient(135deg, #fbf9ff 0%, var(--background-white) 100%);
}

.relation-type-badge.cosine_related {
    background: var(--network-cosine);
}

.relation-item.cosine_related:hover {
    border-color: var(--network-cosine);
    box-shadow: 0 4px 12px rgba(111, 66, 193, 0.2);
}

/* 생성된 주제 (generated) */
.relation-item.generated {
    border-left: 6px solid var(--network-generated);
    background: linear-gradient(135deg, #fbf9ff 0%, var(--background-white) 100%);
}

.relation-type-badge.generated {
    background: var(--network-generated);
}

.relation-item.generated:hover {
    border-color: var(--network-generated);
    box-shadow: 0 4px 12px rgba(111, 66, 193, 0.2);
}

/* 관련 주제 타겟 스타일 */
.relation-target {
    color: #495057;
    font-weight: 600;
    font-size: 16px;
    line-height: 1.4;
    flex: 1;
    text-decoration: none;
    transition: color var(--transition-fast);
}

.relation-target:hover {
    color: var(--info-color);
    text-decoration: underline;
}

.relation-meta {
    color: #6c757d;
    font-size: 13px;
    margin-top: 8px;
    padding-top: 8px;
    border-top: 1px solid var(--background-light);
}

.relation-meta small {
    background: var(--background-light);
    padding: 4px 8px;
    border-radius: 4px;
    font-family: var(--font-family-mono);
}

/* 메타데이터 정보 스타일 */
.metadata-info {
    color: #6c757d;
    font-size: 13px;
    font-weight: normal;
}

/* 관련 도서 스타일 개선 */
.related-books-list {
    max-height: 600px;
    overflow-y: auto;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: var(--spacing-md);
    background-color: #fafafa;
}

.related-book-item {
    border: 1px solid var(--border-color-light);
    border-radius: 6px;
    padding: var(--spacing-md);
    margin-bottom: 12px;
    background-color: var(--background-white);
    transition: all var(--transition-fast);
    cursor: pointer;
}

.related-book-item:hover {
    border-color: var(--info-color);
    box-shadow: 0 2px 8px rgba(0, 123, 255, 0.1);
    transform: translateY(-1px);
}

.related-book-item:last-child {
    margin-bottom: 0;
}

.book-title {
    font-weight: 600;
    font-size: 16px;
    color: var(--text-color);
    margin-bottom: var(--spacing-sm);
    line-height: 1.4;
    border-left: 3px solid var(--primary-color);
    padding-left: 12px;
}

.book-meta {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    font-size: var(--font-size-sm);
    color: var(--text-muted);
    padding-left: var(--spacing-md);
}

.book-meta span {
    background-color: var(--background-light);
    padding: 4px 8px;
    border-radius: 4px;
    border: 1px solid var(--border-color-lighter);
}

.book-intro {
    font-size: var(--font-size-sm);
    color: var(--text-light);
    line-height: 1.4;
    margin-top: var(--spacing-sm);
    padding-left: var(--spacing-md);
    font-style: italic;
}

/* 스크롤바 스타일링 */
.related-books-list::-webkit-scrollbar {
    width: 6px;
}

.related-books-list::-webkit-scrollbar-track {
    background: #f1f1f1;
    border-radius: 3px;
}

.related-books-list::-webkit-scrollbar-thumb {
    background: #c1c1c1;
    border-radius: 3px;
}

.related-books-list::-webkit-scrollbar-thumb:hover {
    background: #a8a8a8;
}


/* 반응형 디자인 */
@media (max-width: 768px) {
    .relation-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
    }
    
    .relation-type-badge {
        align-self: flex-start;
    }
}

/* 연결 유형별 색상 */
.link.broader { stroke: #007bff; }
.link.narrower { stroke: #28a745; }
.link.related { stroke: #ffc107; }
.link.cosine_related { stroke: #6c757d; }

/* 챗봇 스타일 */
.chatbot-container {
    display: flex;
    flex-direction: column;
    height: calc(100vh - 60px);
    min-height: 600px;
    max-width: 1800px;
    margin: 0 auto;
    background: white;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    overflow: hidden;
}

.chatbot-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 20px;
    background: #f8f9fa;
    border-bottom: 1px solid #e9ecef;
}

.new-chat-button {
    background: #2196F3;
    color: white;
    border: none;
    padding: 8px 16px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: background-color 0.2s;
    display: flex;
    align-items: center;
    gap: 6px;
}

.new-chat-button:hover {
    background: #1976D2;
}

.new-chat-button:disabled {
    background: #ccc;
    cursor: not-allowed;
}

.chatbot-status {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 14px;
    color: #6c757d;
}

.status-indicator {
    font-size: 12px;
    color: #28a745;
}

.status-indicator.inactive {
    color: #dc3545;
}

.chat-messages {
    flex: 1;
    padding: 20px;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 16px;
    background: linear-gradient(to bottom, #ffffff 0%, #f8f9fa 100%);
}

.message {
    display: flex;
    flex-direction: column;
    max-width: 80%;
    animation: fadeIn 0.3s ease-in;
}

.bot-message {
    align-self: flex-start;
}

.user-message {
    align-self: flex-end;
}

.message-content {
    padding: 12px 16px;
    border-radius: 18px;
    word-wrap: break-word;
    line-height: 1.4;
}

/* 마크다운 렌더링을 위한 추가 스타일 */
.bot-message .message-content {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border-bottom-left-radius: 8px;
}

/* 마크다운 요소들을 위한 스타일 */
.message-content h1,
.message-content h2,
.message-content h3,
.message-content h4,
.message-content h5,
.message-content h6 {
  margin: 0.5rem 0;
  font-weight: bold;
}

.message-content h1 { font-size: 1.5rem; }
.message-content h2 { font-size: 1.3rem; }
.message-content h3 { font-size: 1.1rem; }

.message-content strong {
  font-weight: bold;
}

.message-content em {
  font-style: italic;
}

.message-content code {
  background: rgba(255, 255, 255, 0.2);
  padding: 2px 4px;
  border-radius: 3px;
  font-family: 'Courier New', monospace;
  font-size: 0.9em;
}

.message-content pre {
  background: rgba(255, 255, 255, 0.1);
  padding: 8px;
  border-radius: 6px;
  overflow-x: auto;
  margin: 8px 0;
}

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

.message-content ul,
.message-content ol {
  margin: 8px 0;
  padding-left: 20px;
}

.message-content li {
  margin: 4px 0;
}

.message-content p {
  margin: 8px 0;
}

.message-content p:first-child {
  margin-top: 0;
}

.message-content p:last-child {
  margin-bottom: 0;
}

.message-content blockquote {
  border-left: 3px solid rgba(255, 255, 255, 0.3);
  padding-left: 12px;
  margin: 8px 0;
  font-style: italic;
}

/* 참조 링크 스타일 */
.message-content .reference-link {
  display: inline-block;
  padding: 2px 8px;
  margin: 0 2px;
  background: rgba(255, 255, 255, 0.2);
  color: rgba(255, 255, 255, 0.9);
  text-decoration: none;
  border-radius: 12px;
  font-size: 0.85em;
  font-weight: 500;
  border: 1px solid rgba(255, 255, 255, 0.3);
  transition: all 0.2s ease;
}

.message-content .reference-link:hover {
  background: rgba(255, 255, 255, 0.3);
  color: white;
  border-color: rgba(255, 255, 255, 0.5);
  transform: translateY(-1px);
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

.message-content .reference-link:active {
  transform: translateY(0);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.2);
}

/* 주제 참조 링크 */
.message-content .reference-link.subject-link {
  border-color: rgba(102, 187, 106, 0.5);
}

.message-content .reference-link.subject-link:hover {
  background: rgba(102, 187, 106, 0.2);
  border-color: rgba(102, 187, 106, 0.7);
}

/* 도서 참조 링크 */
.message-content .reference-link.book-link {
  border-color: rgba(255, 193, 7, 0.5);
}

.message-content .reference-link.book-link:hover {
  background: rgba(255, 193, 7, 0.2);
  border-color: rgba(255, 193, 7, 0.7);
}

/* 사용자 메시지는 기본 스타일 유지 */
.user-message .message-content {
    background: #e3f2fd;
    color: #1976d2;
    border-bottom-right-radius: 8px;
}

.message-time {
    font-size: 11px;
    color: #6c757d;
    margin-top: 4px;
    padding: 0 16px;
}

.bot-message .message-time {
    align-self: flex-start;
}

.user-message .message-time {
    align-self: flex-end;
}

.chat-input-container {
    padding: 20px;
    background: white;
    border-top: 1px solid #e9ecef;
}

.chat-input-group {
    display: flex;
    gap: 12px;
    align-items: flex-end;
}

#chat-input {
    flex: 1;
    min-height: 44px;
    max-height: 120px;
    padding: 12px 16px;
    border: 2px solid #e9ecef;
    border-radius: 22px;
    font-size: 14px;
    font-family: inherit;
    resize: none;
    outline: none;
    transition: border-color 0.2s ease;
}

#chat-input:focus {
    border-color: #667eea;
}

#send-button {
    width: 44px;
    height: 44px;
    border: none;
    border-radius: 50%;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s ease;
    font-size: 16px;
}

#send-button:hover:not(:disabled) {
    transform: scale(1.05);
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.4);
}

#send-button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.typing-indicator {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 12px 16px;
    background: #f1f3f4;
    border-radius: 18px;
    border-bottom-left-radius: 8px;
    max-width: 80px;
    align-self: flex-start;
}

.typing-dots {
    display: flex;
    gap: 4px;
}

.typing-dot {
    width: 8px;
    height: 8px;
    background: #6c757d;
    border-radius: 50%;
    animation: typingAnimation 1.4s infinite;
}

.typing-dot:nth-child(2) {
    animation-delay: 0.2s;
}

.typing-dot:nth-child(3) {
    animation-delay: 0.4s;
}

@keyframes typingAnimation {
    0%, 60%, 100% {
        transform: translateY(0);
        opacity: 0.4;
    }
    30% {
        transform: translateY(-10px);
        opacity: 1;
    }
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* 챗봇 반응형 디자인 */
@media (max-width: 768px) {
    .chatbot-container {
        height: 60vh;
        margin: 0 10px;
    }
    
    .message {
        max-width: 90%;
    }
    
    .chat-messages {
        padding: 15px;
    }
    
    .chat-input-container {
        padding: var(--spacing-md);
    }
}

/* ============================================
   주제 상세 페이지 스타일
   ============================================ */

/* 헤더와 돌아가기 버튼 */
.header-with-back {
    display: flex;
    align-items: center;
    text-align: center;
    gap: var(--spacing-lg);
}
.header-with-back h1 {
    color: var(--text-color);
    font-size: var(--font-size-5xl);
    text-align: center;
    flex: 1;
}

.back-button {
    padding: 10px 16px;
    background: var(--primary-gradient);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: var(--font-size-base);
    font-weight: 500;
    transition: all var(--transition-normal);
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    min-width: 100px;
}

.back-button:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

/* 책 상세 페이지 컨테이너 */
.book-detail-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--spacing-lg);
}

/* 책 내용 스타일 */
.book-content {
    padding: var(--spacing-lg);
    background: var(--background-light);
    border-radius: var(--border-radius-md);
    border: 1px solid var(--border-color-lighter);
    line-height: 1.7;
}

.book-content p {
    margin-bottom: var(--spacing-md);
    color: var(--text-color);
}

.book-content pre {
    font-family: var(--font-family);
    white-space: pre-wrap;
    word-wrap: break-word;
    color: var(--text-color);
    font-size: var(--font-size-base);
    line-height: 1.6;
}

/* NLK 주제 상세 스타일 */
.nlk-subjects-detailed {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: var(--spacing-md);
}

.nlk-subject-detailed {
    background: var(--background-white);
    border: 1px solid var(--border-color-lighter);
    border-radius: var(--border-radius-md);
    padding: var(--spacing-md);
    cursor: pointer;
    transition: all var(--transition-normal);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.nlk-subject-detailed:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
    border-color: var(--primary-color);
}

.nlk-subject-detailed .subject-id {
    font-size: var(--font-size-sm);
    color: var(--primary-color);
    font-weight: 600;
}

.nlk-subject-detailed .subject-label {
    font-size: var(--font-size-base);
    color: var(--text-color);
    font-weight: 500;
}

/* 주제 상세 페이지 컨테이너 */
.subject-detail-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--spacing-lg);
}

/* 상세 섹션 */
.detail-section {
    background: var(--background-white);
    border-radius: var(--border-radius-xl);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color-lighter);
}

.detail-section h2 {
    color: var(--text-color);
    margin-bottom: var(--spacing-lg);
    font-size: var(--font-size-3xl);
    font-weight: 600;
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--border-color-light);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

/* 정보 그리드 */
.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.info-item {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.info-item strong {
    color: var(--text-color);
    font-weight: 600;
    font-size: var(--font-size-lg);
}

.info-item span {
    color: var(--text-muted);
    font-size: var(--font-size-base);
    padding: var(--spacing-sm);
    background: var(--background-light);
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color-lighter);
}

/* 주제 정의 */
.subject-definition-full {
    margin-top: var(--spacing-lg);
    padding: var(--spacing-lg);
    background: var(--background-light);
    border-radius: var(--border-radius-md);
    border-left: 4px solid var(--primary-color);
}

.subject-definition-full h3 {
    color: var(--text-color);
    margin-bottom: var(--spacing-sm);
    font-size: var(--font-size-xl);
}

.subject-definition-full p {
    color: var(--text-muted);
    line-height: 1.7;
    font-size: var(--font-size-base);
}

/* 관련 도서 그리드 */
.related-books-grid {
    display: grid;
    max-height: 600px;
    overflow-y: auto;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--spacing-lg);
}

.related-book-card {
    background: var(--background-light);
    border: 1px solid var(--border-color-lighter);
    border-radius: var(--border-radius-md);
    padding: var(--spacing-lg);
    transition: all var(--transition-normal);
    cursor: pointer;
}

.related-book-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
    border-color: var(--primary-color);
}

.related-book-card .book-title {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: var(--spacing-sm);
    line-height: 1.4;
}

.related-book-card .book-meta {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-sm);
}

.related-book-card .book-meta span {
    font-size: var(--font-size-sm);
    color: var(--text-muted);
}

.related-book-card .book-intro {
    font-size: var(--font-size-sm);
    color: var(--text-light);
    line-height: 1.5;
    margin-top: var(--spacing-sm);
    padding-top: var(--spacing-sm);
    border-top: 1px solid var(--border-color-lighter);
}

/* 관련 주제 그리드 */
.relations-grid {
    display: grid;
    max-height: 1000px;
    overflow-y: auto;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--spacing-lg);
}

.relation-card {
    background: var(--background-white);
    border: 1px solid var(--border-color-lighter);
    border-radius: var(--border-radius-md);
    padding: var(--spacing-lg);
    cursor: pointer;
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.relation-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.relation-card.broader {
    border-left: 4px solid var(--network-broader);
}

.relation-card.narrower {
    border-left: 4px solid var(--network-narrower);
}

.relation-card.related {
    border-left: 4px solid var(--network-related);
}

.relation-card.cosine {
    border-left: 4px solid var(--network-cosine);
}

.relation-card.generated {
    border-left: 4px solid var(--network-generated);
}

.relation-card .relation-header {
    margin-bottom: var(--spacing-sm);
}

.relation-card .relation-type-badge {
    display: inline-block;
    padding: 4px 8px;
    border-radius: var(--border-radius-pill);
    font-size: var(--font-size-xs);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.relation-card .relation-type-badge.broader {
    background: var(--network-broader);
    color: white;
}

.relation-card .relation-type-badge.narrower {
    background: var(--network-narrower);
    color: white;
}

.relation-card .relation-type-badge.related {
    background: var(--network-related);
    color: var(--text-color);
}

.relation-card .relation-type-badge.cosine {
    background: var(--network-cosine);
    color: white;
}

.relation-card .relation-type-badge.generated {
    background: var(--network-generated);
    color: white;
}

.relation-card .relation-content h4 {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: var(--spacing-xs);
    line-height: 1.3;
}

.relation-card .relation-id {
    font-size: var(--font-size-xs);
    color: var(--text-muted);
    margin-bottom: var(--spacing-xs);
}

.relation-card .similarity-score {
    font-size: var(--font-size-sm);
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}
.relation-card .predicate-info {
    font-size: var(--font-size-sm);
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}

.relation-card .source-info {
    font-size: var(--font-size-xs);
    color: var(--text-light);
    background: var(--background-light);
    padding: 2px 6px;
    border-radius: var(--border-radius);
    display: inline-block;
}

/* 모달 액션 버튼 */
.modal-actions {
    margin: var(--spacing-lg) 0;
    padding: var(--spacing-lg) 0;
    border-top: 1px solid var(--border-color-lighter);
    border-bottom: 1px solid var(--border-color-lighter);
    text-align: center;
}

.detail-page-button {
    background: var(--primary-gradient);
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: var(--border-radius-md);
    cursor: pointer;
    font-size: var(--font-size-base);
    font-weight: 600;
    transition: all var(--transition-normal);
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.detail-page-button:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

/* 더 보기 정보 */
.more-info {
    text-align: center;
    color: var(--text-muted);
    font-style: italic;
    margin-top: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--background-light);
    border-radius: var(--border-radius);
}

/* 로딩 및 에러 스타일 */
.loading-container {
    text-align: center;
    padding: var(--spacing-xl);
    color: var(--text-muted);
}

.loading-spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--border-color-lighter);
    border-top: 4px solid var(--primary-color);
    border-radius: var(--border-radius-circle);
    animation: spin 1s linear infinite;
    margin: 0 auto var(--spacing-md);
}

.error-container {
    text-align: center;
    padding: var(--spacing-xl);
    color: var(--danger-color);
}

.error-container h2 {
    margin-bottom: var(--spacing-md);
}

.error-container p {
    margin-bottom: var(--spacing-lg);
    color: var(--text-muted);
}

/* 반응형 디자인 */
@media (max-width: 768px) {
    .header-with-back {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-md);
    }
    
    .subject-detail-container {
        padding: var(--spacing-md);
    }
    
    .detail-section {
        padding: var(--spacing-lg);
        margin-bottom: var(--spacing-lg);
    }
    
    .info-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
    }
    
    .related-books-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
    }
    
    .relations-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
    }
    
    .relation-card {
        padding: var(--spacing-md);
    }
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* ============================================
   KDC 접근점 스타일
   ============================================ */

/* KDC 접근점 그리드 */
.kdc-access-points-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-md);
}

/* KDC 접근점 카드 */
.kdc-access-point-card {
    background: var(--background-white);
    border-radius: var(--border-radius-md);
    border: 1px solid var(--border-color);
    padding: var(--spacing-lg);
    transition: all 0.3s ease;
    cursor: pointer;
}

/* KDC 분류별 색상 (첫 번째 자리 숫자 기준) */
.kdc-access-point-card.kdc-0 {
    border-left: 4px solid #797979; /* 총류 - 회색 */
}

.kdc-access-point-card.kdc-1 {
    border-left: 4px solid #75c8ff; /* 철학 - 파란색 */
}

.kdc-access-point-card.kdc-2 {
    border-left: 4px solid #722ecc; /* 종교 - 진한 보라색 */
}

.kdc-access-point-card.kdc-3 {
    border-left: 4px solid #f39c12; /* 사회과학 - 주황색 */
}

.kdc-access-point-card.kdc-4 {
    border-left: 4px solid #70b659; /* 자연과학 - 녹색 */
}

.kdc-access-point-card.kdc-5 {
    border-left: 4px solid #0a08a5; /* 기술과학 - 진한 파란색 */
}

.kdc-access-point-card.kdc-6 {
    border-left: 4px solid #e62222; /* 예술 - 진한 빨간색 */
}

.kdc-access-point-card.kdc-7 {
    border-left: 4px solid #fffc3b; /* 언어 - 노란색 */
}

.kdc-access-point-card.kdc-8 {
    border-left: 4px solid #e76f97; /* 문학 - 분홍색 */
}

.kdc-access-point-card.kdc-9 {
    border-left: 4px solid #000000; /* 역사 - 검정색 */
}

.kdc-access-point-card:hover {
    box-shadow: var(--shadow-hover);
    transform: translateY(-2px);
}

/* KDC 헤더 */
.kdc-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-sm);
}

.kdc-number {
    font-size: var(--font-size-lg);
    font-weight: bold;
    color: var(--primary-color);
    background: rgba(102, 126, 234, 0.1);
    padding: 4px 8px;
    border-radius: var(--border-radius);
}

.kdc-type-badge {
    font-size: var(--font-size-xs);
    padding: 2px 8px;
    border-radius: var(--border-radius-pill);
    color: white;
    font-weight: 500;
}

.kdc-type-badge.direct {
    background-color: #28a745;
}

.kdc-type-badge.indirect {
    background-color: #6c757d;
}

/* KDC 라벨 */
.kdc-label {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: var(--spacing-md);
    line-height: 1.4;
}

/* KDC 관련 도서 미리보기 */
.kdc-books-preview {
    border-top: 1px solid var(--border-color-light);
    padding-top: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.books-count {
    font-size: var(--font-size-sm);
    color: var(--text-muted);
    margin-bottom: var(--spacing-sm);
    font-weight: 500;
}

.sample-books {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.sample-book {
    background: var(--background-lighter);
    padding: var(--spacing-sm);
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: background-color 0.2s ease;
}

.sample-book:hover {
    background: var(--border-color-light);
}

.sample-book .book-title {
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--text-color);
    margin-bottom: 2px;
    line-height: 1.3;
}

.sample-book .book-year {
    font-size: var(--font-size-xs);
    color: var(--text-muted);
}

.more-books {
    font-size: var(--font-size-xs);
    color: var(--text-muted);
    text-align: center;
    padding: var(--spacing-xs);
    font-style: italic;
}

/* 반응형 디자인 - KDC 접근점 */
@media (max-width: 768px) {
    .kdc-access-points-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
    }
    
    .kdc-access-point-card {
        padding: var(--spacing-md);
    }
    
    .kdc-header {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-xs);
    }
    
    .kdc-number {
        font-size: var(--font-size-base);
    }
    
    .kdc-label {
        font-size: var(--font-size-base);
    }
}

/* ============================================
   CSS 변수 기반 스타일시트 정리 완료
   
   구조:
   1. CSS 변수 정의 (:root)
   2. 기본 스타일 및 유틸리티 클래스
   3. 레이아웃 (앱 컨테이너, 사이드바, 메인 콘텐츠)
   4. 컴포넌트별 스타일:
      - 검색 관련
      - 결과 표시
      - 모달
      - 관련 주제/도서
      - 네트워크 시각화
      - 챗봇
      - 주제 상세 페이지
      - KDC 접근점
   5. 반응형 디자인
   
   장점:
   - 일관된 디자인 시스템
   - 유지보수 용이성
   - 재사용 가능한 컴포넌트
   - 쉬운 테마 변경
   ============================================ */