/* ==========================================================================
   GEO/SEO/AEO 최적화 가이드 - 메인 스타일시트
   Google 공식 문서 기반 웹 표준 CSS
   ========================================================================== */

/* CSS 변수 (디자인 토큰) */
:root {
  /* 색상 팔레트 */
  --color-primary: #1a73e8;
  --color-primary-dark: #1557b0;
  --color-primary-light: #e8f0fe;
  --color-secondary: #34a853;
  --color-accent: #fbbc04;
  --color-danger: #ea4335;
  --color-warning: #ff9800;

  /* 중성 색상 */
  --color-text: #202124;
  --color-text-secondary: #5f6368;
  --color-text-light: #80868b;
  --color-bg: #ffffff;
  --color-bg-secondary: #f8f9fa;
  --color-bg-tertiary: #f1f3f4;
  --color-border: #dadce0;
  --color-border-light: #e8eaed;

  /* 다크모드 */
  --color-dark-text: #e8eaed;
  --color-dark-text-secondary: #bdc1c6;
  --color-dark-bg: #202124;
  --color-dark-bg-secondary: #292a2d;
  --color-dark-bg-tertiary: #35363a;
  --color-dark-border: #3c4043;

  /* 타이포그래피 */
  --font-primary: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans KR", sans-serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  --font-size-base: 16px;
  --font-size-sm: 14px;
  --font-size-lg: 18px;
  --font-size-xl: 20px;
  --font-size-2xl: 24px;
  --font-size-3xl: 32px;
  --font-size-4xl: 42px;
  --font-size-5xl: 56px;

  /* 간격 */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;
  --space-10: 40px;
  --space-12: 48px;
  --space-16: 64px;
  --space-20: 80px;
  --space-24: 96px;

  /* 그림자 */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 2px 4px rgba(0, 0, 0, 0.08), 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 4px 8px rgba(0, 0, 0, 0.1), 0 2px 4px rgba(0, 0, 0, 0.06);
  --shadow-xl: 0 8px 24px rgba(0, 0, 0, 0.12);
  --shadow-2xl: 0 16px 48px rgba(0, 0, 0, 0.15);

  /* 둥근 모서리 */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-2xl: 24px;
  --radius-full: 9999px;

  /* 전환 애니메이션 */
  --transition-fast: 150ms ease-in-out;
  --transition-base: 250ms ease-in-out;
  --transition-slow: 350ms ease-in-out;

  /* z-index */
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-header: 300;
  --z-modal: 400;
  --z-toast: 500;

  /* 컨테이너 */
  --container-max: 1200px;
  --container-padding: var(--space-6);
}

/* 다크모드 변수 */
[data-theme="dark"] {
  --color-text: var(--color-dark-text);
  --color-text-secondary: var(--color-dark-text-secondary);
  --color-bg: var(--color-dark-bg);
  --color-bg-secondary: var(--color-dark-bg-secondary);
  --color-bg-tertiary: var(--color-dark-bg-tertiary);
  --color-border: var(--color-dark-border);
  --color-border-light: var(--color-dark-border);
}

/* ==========================================================================
   리셋 & 베이스
   ========================================================================== */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: var(--font-size-base);
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

body {
  font-family: var(--font-primary);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background-color var(--transition-base), color var(--transition-base);
}

img,
picture,
video,
canvas,
svg {
  display: block;
  max-width: 100%;
  height: auto;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-primary-dark);
  text-decoration: underline;
}

a:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

button {
  font-family: inherit;
  font-size: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

input,
textarea,
select {
  font-family: inherit;
  font-size: inherit;
}

/* ==========================================================================
   타이포그래피
   ========================================================================== */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.3;
  color: var(--color-text);
  margin-bottom: var(--space-4);
}

h1 { font-size: var(--font-size-4xl); }
h2 { font-size: var(--font-size-3xl); }
h3 { font-size: var(--font-size-2xl); }
h4 { font-size: var(--font-size-xl); }
h5 { font-size: var(--font-size-lg); }
h6 { font-size: var(--font-size-base); }

p {
  margin-bottom: var(--space-4);
}

ul, ol {
  padding-left: var(--space-6);
  margin-bottom: var(--space-4);
}

li {
  margin-bottom: var(--space-2);
}

code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background-color: var(--color-bg-tertiary);
  padding: 2px 6px;
  border-radius: var(--radius-sm);
  color: var(--color-danger);
}

pre {
  background-color: var(--color-dark-bg);
  color: #e8eaed;
  padding: var(--space-5);
  border-radius: var(--radius-md);
  overflow-x: auto;
  margin-bottom: var(--space-4);
  font-size: var(--font-size-sm);
  line-height: 1.5;
}

pre code {
  background: none;
  color: inherit;
  padding: 0;
  font-size: inherit;
}

blockquote {
  border-left: 4px solid var(--color-primary);
  padding: var(--space-3) var(--space-5);
  margin: var(--space-4) 0;
  background-color: var(--color-primary-light);
  border-radius: var(--radius-sm);
  font-style: italic;
}

/* ==========================================================================
   레이아웃 유틸리티
   ========================================================================== */
.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

.section {
  padding: var(--space-20) 0;
}

.section-sm {
  padding: var(--space-12) 0;
}

.grid {
  display: grid;
  gap: var(--space-6);
}

.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

@media (max-width: 1024px) {
  .grid-3, .grid-4 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 640px) {
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  h1 { font-size: var(--font-size-3xl); }
  h2 { font-size: var(--font-size-2xl); }
  .section { padding: var(--space-12) 0; }
}

/* ==========================================================================
   헤더 & 네비게이션
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  background-color: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-border-light);
  z-index: var(--z-header);
  transition: background-color var(--transition-base);
}

[data-theme="dark"] .site-header {
  background-color: rgba(32, 33, 36, 0.95);
}

.nav-container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: var(--space-4) var(--container-padding);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-6);
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--font-size-lg);
  font-weight: 700;
  color: var(--color-text);
  text-decoration: none;
}

.logo-icon {
  width: 32px;
  height: 32px;
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 700;
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: var(--space-2);
  margin: 0;
  padding: 0;
}

.nav-menu a {
  display: block;
  padding: var(--space-2) var(--space-3);
  color: var(--color-text-secondary);
  font-weight: 500;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
}

.nav-menu a:hover,
.nav-menu a.active {
  color: var(--color-primary);
  background-color: var(--color-primary-light);
  text-decoration: none;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.theme-toggle {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
}

.theme-toggle:hover {
  background-color: var(--color-bg-tertiary);
  color: var(--color-text);
}

.mobile-menu-btn {
  display: none;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  align-items: center;
  justify-content: center;
  color: var(--color-text);
}

@media (max-width: 768px) {
  .nav-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--color-bg);
    flex-direction: column;
    padding: var(--space-4);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-lg);
  }
  .nav-menu.active { display: flex; }
  .mobile-menu-btn { display: flex; }
}

/* ==========================================================================
   버튼
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-5);
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: var(--font-size-base);
  text-decoration: none;
  transition: all var(--transition-fast);
  border: 2px solid transparent;
  white-space: nowrap;
}

.btn:hover {
  text-decoration: none;
  transform: translateY(-1px);
}

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

.btn-primary:hover {
  background-color: var(--color-primary-dark);
  color: white;
  box-shadow: var(--shadow-md);
}

.btn-secondary {
  background-color: var(--color-bg-tertiary);
  color: var(--color-text);
}

.btn-secondary:hover {
  background-color: var(--color-border);
  color: var(--color-text);
}

.btn-outline {
  background-color: transparent;
  color: var(--color-primary);
  border-color: var(--color-primary);
}

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

.btn-lg {
  padding: var(--space-4) var(--space-8);
  font-size: var(--font-size-lg);
}

/* ==========================================================================
   히어로 섹션
   ========================================================================== */
.hero {
  padding: var(--space-24) 0;
  background: linear-gradient(135deg, var(--color-primary-light) 0%, var(--color-bg) 100%);
  text-align: center;
  position: relative;
  overflow: hidden;
}

[data-theme="dark"] .hero {
  background: linear-gradient(135deg, var(--color-dark-bg-secondary) 0%, var(--color-dark-bg) 100%);
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -10%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(26, 115, 232, 0.1) 0%, transparent 70%);
  border-radius: 50%;
  z-index: 0;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
  margin: 0 auto;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-6);
  box-shadow: var(--shadow-sm);
}

.hero h1 {
  font-size: var(--font-size-5xl);
  margin-bottom: var(--space-6);
  line-height: 1.1;
}

.hero-subtitle {
  font-size: var(--font-size-xl);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-8);
  line-height: 1.5;
}

.hero-actions {
  display: flex;
  gap: var(--space-4);
  justify-content: center;
  flex-wrap: wrap;
}

@media (max-width: 640px) {
  .hero { padding: var(--space-16) 0; }
  .hero h1 { font-size: var(--font-size-4xl); }
  .hero-subtitle { font-size: var(--font-size-lg); }
}

/* ==========================================================================
   카드
   ========================================================================== */
.card {
  background-color: var(--color-bg);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  transition: all var(--transition-base);
  height: 100%;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-primary);
}

.card-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, var(--color-primary-light), var(--color-bg));
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-primary);
  margin-bottom: var(--space-4);
  font-size: var(--font-size-xl);
}

.card h3 {
  font-size: var(--font-size-xl);
  margin-bottom: var(--space-3);
}

.card p {
  color: var(--color-text-secondary);
  margin-bottom: var(--space-4);
}

.card-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  color: var(--color-primary);
  font-weight: 600;
}

/* ==========================================================================
   콘텐츠 섹션
   ========================================================================== */
.content {
  max-width: 800px;
  margin: 0 auto;
  padding: var(--space-8) var(--container-padding);
}

.content h2 {
  margin-top: var(--space-12);
  padding-top: var(--space-8);
  border-top: 1px solid var(--color-border-light);
}

.content h2:first-child {
  margin-top: 0;
  padding-top: 0;
  border-top: none;
}

.content h3 {
  margin-top: var(--space-8);
  color: var(--color-primary);
}

.callout {
  padding: var(--space-5);
  border-radius: var(--radius-md);
  margin: var(--space-6) 0;
  border-left: 4px solid;
}

.callout-info {
  background-color: var(--color-primary-light);
  border-color: var(--color-primary);
}

.callout-success {
  background-color: #e6f4ea;
  border-color: var(--color-secondary);
}

[data-theme="dark"] .callout-success {
  background-color: rgba(52, 168, 83, 0.15);
}

.callout-warning {
  background-color: #fef7e0;
  border-color: var(--color-warning);
}

[data-theme="dark"] .callout-warning {
  background-color: rgba(251, 188, 4, 0.15);
}

.callout-danger {
  background-color: #fce8e6;
  border-color: var(--color-danger);
}

[data-theme="dark"] .callout-danger {
  background-color: rgba(234, 67, 53, 0.15);
}

.callout-title {
  font-weight: 700;
  margin-bottom: var(--space-2);
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

/* ==========================================================================
   체크리스트
   ========================================================================== */
.checklist {
  list-style: none;
  padding: 0;
  margin: var(--space-6) 0;
}

.checklist li {
  padding: var(--space-3) 0;
  padding-left: var(--space-8);
  position: relative;
  border-bottom: 1px solid var(--color-border-light);
}

.checklist li:last-child {
  border-bottom: none;
}

.checklist li::before {
  content: '☐';
  position: absolute;
  left: 0;
  top: var(--space-3);
  font-size: var(--font-size-lg);
  color: var(--color-text-secondary);
}

.checklist li.checked::before {
  content: '☑';
  color: var(--color-secondary);
}

/* ==========================================================================
   코드 블록 & 스키마
   ========================================================================== */
.code-tabs {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  margin: var(--space-6) 0;
}

.code-tabs-header {
  display: flex;
  background-color: var(--color-bg-tertiary);
  border-bottom: 1px solid var(--color-border);
}

.code-tab {
  padding: var(--space-3) var(--space-5);
  background: none;
  color: var(--color-text-secondary);
  font-weight: 500;
  border-bottom: 2px solid transparent;
  transition: all var(--transition-fast);
}

.code-tab.active {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
  background-color: var(--color-bg);
}

.code-tab-content {
  display: none;
  padding: var(--space-5);
  background-color: var(--color-bg);
}

.code-tab-content.active {
  display: block;
}

.code-tab-content pre {
  margin: 0;
  background-color: var(--color-dark-bg);
}

/* ==========================================================================
   통계 카드
   ========================================================================== */
.stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-4);
  margin: var(--space-8) 0;
}

.stat-card {
  text-align: center;
  padding: var(--space-6);
  background-color: var(--color-bg-secondary);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border-light);
}

.stat-number {
  font-size: var(--font-size-4xl);
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1;
  margin-bottom: var(--space-2);
}

.stat-label {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

/* ==========================================================================
   비교 테이블
   ========================================================================== */
.comparison-table {
  width: 100%;
  border-collapse: collapse;
  margin: var(--space-6) 0;
  background-color: var(--color-bg);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.comparison-table th,
.comparison-table td {
  padding: var(--space-4);
  text-align: left;
  border-bottom: 1px solid var(--color-border-light);
}

.comparison-table th {
  background-color: var(--color-bg-tertiary);
  font-weight: 700;
  color: var(--color-text);
}

.comparison-table tr:hover {
  background-color: var(--color-bg-secondary);
}

@media (max-width: 640px) {
  .comparison-table { font-size: var(--font-size-sm); }
  .comparison-table th,
  .comparison-table td { padding: var(--space-3); }
}

/* ==========================================================================
   진행 표시기
   ========================================================================== */
.progress-bar {
  width: 100%;
  height: 8px;
  background-color: var(--color-bg-tertiary);
  border-radius: var(--radius-full);
  overflow: hidden;
  margin: var(--space-2) 0;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
  border-radius: var(--radius-full);
  transition: width var(--transition-slow);
}

/* ==========================================================================
   푸터
   ========================================================================== */
.site-footer {
  background-color: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border-light);
  padding: var(--space-16) 0 var(--space-8);
  margin-top: var(--space-24);
}

[data-theme="dark"] .site-footer {
  background-color: var(--color-dark-bg-secondary);
}

.footer-content {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-padding);
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-8);
  margin-bottom: var(--space-8);
}

@media (max-width: 768px) {
  .footer-content { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 480px) {
  .footer-content { grid-template-columns: 1fr; }
}

.footer-section h4 {
  font-size: var(--font-size-base);
  margin-bottom: var(--space-4);
  color: var(--color-text);
}

.footer-section ul {
  list-style: none;
  padding: 0;
}

.footer-section li {
  margin-bottom: var(--space-2);
}

.footer-linkbar {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 10px;
  font-size: var(--font-size-sm);
  line-height: 1.7;
}

.footer-linkbar a {
  white-space: nowrap;
}

.footer-section a {
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
}

.footer-section a:hover {
  color: var(--color-primary);
}

.footer-bottom {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: var(--space-6) var(--container-padding);
  border-top: 1px solid var(--color-border-light);
  text-align: center;
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
}

/* ==========================================================================
   도구 & 폼
   ========================================================================== */
.tool-container {
  max-width: 800px;
  margin: 0 auto;
  padding: var(--space-6);
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}

.form-group {
  margin-bottom: var(--space-5);
}

.form-label {
  display: block;
  font-weight: 600;
  margin-bottom: var(--space-2);
  color: var(--color-text);
}

.form-input,
.form-textarea,
.form-select {
  width: 100%;
  padding: var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background-color: var(--color-bg);
  color: var(--color-text);
  font-size: var(--font-size-base);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-input:focus,
.form-textarea:focus,
.form-select:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-light);
}

.form-textarea {
  min-height: 120px;
  resize: vertical;
  font-family: var(--font-mono);
}

.form-help {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  margin-top: var(--space-1);
}

/* ==========================================================================
   사이드바 네비게이션
   ========================================================================== */
.layout-with-sidebar {
  display: grid;
  grid-template-columns: 250px 1fr;
  gap: var(--space-8);
  max-width: var(--container-max);
  margin: 0 auto;
  padding: var(--space-8) var(--container-padding);
}

.sidebar {
  position: sticky;
  top: 80px;
  height: fit-content;
}

.sidebar-nav {
  background-color: var(--color-bg-secondary);
  border-radius: var(--radius-md);
  padding: var(--space-4);
}

.sidebar-nav h4 {
  font-size: var(--font-size-sm);
  text-transform: uppercase;
  color: var(--color-text-light);
  margin-bottom: var(--space-3);
  letter-spacing: 0.5px;
}

.sidebar-nav ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.sidebar-nav li {
  margin: 0;
}

.sidebar-nav a {
  display: block;
  padding: var(--space-2) var(--space-3);
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.sidebar-nav a:hover,
.sidebar-nav a.active {
  background-color: var(--color-primary-light);
  color: var(--color-primary);
  text-decoration: none;
}

@media (max-width: 1024px) {
  .layout-with-sidebar {
    grid-template-columns: 1fr;
  }
  .sidebar {
    position: static;
  }
}

/* ==========================================================================
   페이지 헤더
   ========================================================================== */
.page-header {
  padding: var(--space-16) 0 var(--space-8);
  background: linear-gradient(180deg, var(--color-primary-light) 0%, var(--color-bg) 100%);
  text-align: center;
}

[data-theme="dark"] .page-header {
  background: linear-gradient(180deg, var(--color-dark-bg-secondary) 0%, var(--color-dark-bg) 100%);
}

.page-header h1 {
  margin-bottom: var(--space-4);
}

.page-header p {
  font-size: var(--font-size-lg);
  color: var(--color-text-secondary);
  max-width: 700px;
  margin: 0 auto;
}

.breadcrumb {
  display: flex;
  list-style: none;
  padding: 0;
  margin: var(--space-4) 0;
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  justify-content: center;
}

.breadcrumb li:not(:last-child)::after {
  content: '›';
  margin: 0 var(--space-2);
}

.breadcrumb a {
  color: var(--color-text-secondary);
}

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

@keyframes slideIn {
  from { opacity: 0; transform: translateX(-20px); }
  to { opacity: 1; transform: translateX(0); }
}

.fade-in {
  animation: fadeIn 0.6s ease-out;
}

.slide-in {
  animation: slideIn 0.5s ease-out;
}

/* ==========================================================================
   유틸리티
   ========================================================================== */
.text-center { text-align: center; }
.text-primary { color: var(--color-primary); }
.text-secondary { color: var(--color-text-secondary); }
.text-success { color: var(--color-secondary); }
.text-danger { color: var(--color-danger); }
.text-warning { color: var(--color-warning); }

.font-bold { font-weight: 700; }
.font-semibold { font-weight: 600; }
.font-medium { font-weight: 500; }

.mb-0 { margin-bottom: 0; }
.mb-2 { margin-bottom: var(--space-2); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-6 { margin-bottom: var(--space-6); }
.mb-8 { margin-bottom: var(--space-8); }

.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mt-8 { margin-top: var(--space-8); }

.hidden { display: none; }
.block { display: block; }

.flex { display: flex; }
.flex-center { display: flex; align-items: center; justify-content: center; }
.gap-2 { gap: var(--space-2); }
.gap-4 { gap: var(--space-4); }

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ==========================================================================
   인쇄 스타일
   ========================================================================== */
@media print {
  .site-header,
  .site-footer,
  .nav-actions,
  .theme-toggle,
  .mobile-menu-btn {
    display: none;
  }
  body {
    color: #000;
    background: #fff;
  }
  a {
    text-decoration: underline;
    color: #000;
  }
}

/* ==========================================================================
   드롭다운 내비게이션
   ========================================================================== */
.nav-menu > li {
  position: relative;
}

.nav-menu > li > .nav-link {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: var(--space-2) var(--space-3);
  color: var(--color-text-secondary);
  font-weight: 500;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  user-select: none;
  white-space: nowrap;
}

.nav-menu > li > .nav-link:hover,
.nav-menu > li > .nav-link.active,
.nav-menu > li.has-dropdown:hover > .nav-link {
  color: var(--color-primary);
  background-color: var(--color-primary-light);
  text-decoration: none;
}

.nav-arrow {
  font-size: 10px;
  transition: transform var(--transition-fast);
}

.has-dropdown:hover .nav-arrow {
  transform: rotate(180deg);
}

.nav-dropdown {
  position: absolute;
  top: calc(100% + 4px);
  left: 0;
  min-width: 220px;
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  list-style: none;
  margin: 0;
  padding: var(--space-2);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-8px);
  transition: opacity var(--transition-fast), transform var(--transition-fast), visibility var(--transition-fast);
  z-index: var(--z-dropdown);
}

.has-dropdown:hover .nav-dropdown,
.has-dropdown:focus-within .nav-dropdown {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.nav-dropdown li {
  margin: 0;
  padding: 0;
}

.nav-dropdown a {
  display: block;
  padding: var(--space-2) var(--space-3);
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
  font-weight: 500;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.nav-dropdown a:hover,
.nav-dropdown a.active {
  color: var(--color-primary);
  background-color: var(--color-primary-light);
  text-decoration: none;
}

@media (max-width: 768px) {
  .nav-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--color-bg);
    flex-direction: column;
    padding: var(--space-4);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-lg);
    max-height: calc(100vh - 70px);
    overflow-y: auto;
  }
  .nav-menu.active { display: flex; }
  .mobile-menu-btn { display: flex; }

  .nav-menu > li > .nav-link {
    padding: var(--space-3) var(--space-2);
    width: 100%;
    justify-content: space-between;
  }

  .nav-dropdown {
    position: static;
    opacity: 1;
    visibility: visible;
    transform: none;
    box-shadow: none;
    border: none;
    background-color: var(--color-bg-secondary);
    margin-top: var(--space-1);
    padding: var(--space-1) var(--space-3);
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-fast);
  }

  .has-dropdown.open .nav-dropdown {
    max-height: 500px;
  }

  .has-dropdown.open .nav-arrow {
    transform: rotate(180deg);
  }
}