/* =============================================
   Git & GitHub 강의 사이트 - 전역 스타일
   ============================================= */
@import url('https://fonts.googleapis.com/css2?family=Pretendard:wght@300;400;500;600;700&family=JetBrains+Mono:wght@400;500&display=swap');

/* ── 디자인 토큰 ── */
:root {
  --bg-primary: #ffffff;
  --bg-secondary: #f6f8fa;
  --bg-tertiary: #f3f4f6;
  --bg-card: #ffffff;
  --bg-hover: #f3f4f6;
  --border: #d0d7de;
  --border-light: #e1e4e8;

  --text-primary: #1f2328;
  --text-secondary: #656d76;
  --text-muted: #6e7781;

  --accent: #1a7f37;
  --accent-hover: #116329;
  --accent-dim: rgba(26, 127, 55, .1);

  --green: #1a7f37;
  --green-dim: rgba(26, 127, 55, .1);
  --yellow: #9a6700;
  --yellow-dim: rgba(154, 103, 0, .1);
  --purple: #8250df;
  --purple-dim: rgba(130, 80, 223, .1);
  --red: #cf222e;
  --red-dim: rgba(207, 34, 46, .1);
  --orange: #bc4c00;
  --orange-dim: rgba(188, 76, 0, .1);

  /* Git 영역 색상 */
  --wd-color: #bc4c00;
  /* Working Directory (Orange) */
  --sa-color: #9a6700;
  /* Staging Area (Yellow) */
  --lr-color: #1a7f37;
  /* Local Repository (Green) */
  --rr-color: #8250df;
  /* Remote Repository (Purple) */

  --sidebar-width: 260px;
  --header-height: 60px;
  --radius: 8px;
  --radius-lg: 12px;
  --shadow: 0 1px 3px rgba(31, 35, 40, .12);
  --shadow-lg: 0 8px 32px rgba(31, 35, 40, .15);

  --transition: 0.2s ease;
  --font-code: 'JetBrains Mono', 'Courier New', monospace;
  --font-body: 'Pretendard', -apple-system, sans-serif;
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-body);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  overflow-x: hidden;
}

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

a:hover {
  color: var(--accent-hover);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* ── 스크롤바 ── */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: var(--bg-primary);
}

::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--bg-hover);
}

/* ========================================
   레이아웃
   ======================================== */
.layout {
  display: flex;
  min-height: 100vh;
}

/* ── 사이드바 ── */
.sidebar {
  width: var(--sidebar-width);
  background: var(--bg-secondary);
  border-right: 1px solid var(--border);
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  overflow-y: auto;
  z-index: 100;
  transition: transform var(--transition);
}

.sidebar-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 20px 20px 16px;
  border-bottom: 1px solid var(--border);
  text-decoration: none;
}

.sidebar-logo .logo-icon {
  width: 32px;
  height: 32px;
  background: linear-gradient(135deg, #aff5b4 0%, #34d058 100%);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  box-shadow: 0 2px 4px rgba(46, 164, 79, 0.15);
}

.sidebar-logo .logo-text {
  font-size: 14px;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.2;
}

.sidebar-logo .logo-sub {
  font-size: 11px;
  color: var(--text-muted);
  font-weight: 400;
}

.sidebar-section {
  padding: 12px 12px 4px;
}

.sidebar-section-title {
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--text-muted);
  padding: 0 8px 8px;
}

.sidebar-nav {
  list-style: none;
}

.sidebar-nav li {
  margin: 1px 0;
}

.sidebar-nav a {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 10px;
  border-radius: var(--radius);
  font-size: 13px;
  color: var(--text-secondary);
  text-decoration: none;
  transition: all var(--transition);
  position: relative;
}

.sidebar-nav a:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
}

.sidebar-nav a.active {
  background: var(--accent-dim);
  color: var(--accent);
  font-weight: 600;
}

.sidebar-nav a .nav-num {
  font-size: 11px;
  color: var(--text-muted);
  min-width: 18px;
  font-weight: 500;
  font-family: var(--font-code);
}

.sidebar-nav a.active .nav-num {
  color: var(--accent);
}

.sidebar-nav a .nav-check {
  margin-left: auto;
  width: 14px;
  height: 14px;
  border: 1.5px solid var(--border);
  border-radius: 50%;
  flex-shrink: 0;
  transition: all var(--transition);
}

.sidebar-nav a.completed .nav-check {
  background: var(--green);
  border-color: var(--green);
  display: flex;
  align-items: center;
  justify-content: center;
}

.sidebar-nav a.completed .nav-check::after {
  content: '✓';
  font-size: 8px;
  color: #000;
  font-weight: 700;
}

.sidebar-progress {
  padding: 12px 20px 20px;
  border-top: 1px solid var(--border);
  margin-top: 8px;
}

.progress-label {
  display: flex;
  justify-content: space-between;
  font-size: 12px;
  color: var(--text-muted);
  margin-bottom: 6px;
}

.progress-bar-bg {
  background: var(--bg-hover);
  border-radius: 4px;
  height: 4px;
}

.progress-bar-fill {
  background: linear-gradient(90deg, var(--accent), var(--green));
  height: 100%;
  border-radius: 4px;
  transition: width 0.5s ease;
}

/* ── 메인 컨텐츠 ── */
.main-content {
  margin-left: var(--sidebar-width);
  flex: 1;
  min-height: 100vh;
}

/* ── 헤더 ── */
.chapter-header {
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border);
  padding: 0 48px;
  height: var(--header-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(8px);
}

.chapter-header-left {
  display: flex;
  align-items: center;
  gap: 12px;
}

.chapter-part-badge {
  font-size: 11px;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: 4px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.part-1 {
  background: var(--orange-dim);
  color: var(--orange);
}

.part-2 {
  background: var(--yellow-dim);
  color: var(--yellow);
}

.part-3 {
  background: var(--green-dim);
  color: var(--green);
}

.part-4 {
  background: var(--purple-dim);
  color: var(--purple);
}

.chapter-progress-text {
  font-size: 13px;
  color: var(--text-muted);
}

.btn-complete {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 7px 16px;
  border-radius: var(--radius);
  background: var(--bg-tertiary);
  border: 1.5px solid var(--border);
  color: var(--text-secondary);
  font-size: 13px;
  font-family: var(--font-body);
  cursor: pointer;
  transition: all var(--transition);
}

.btn-complete:hover {
  background: var(--green-dim);
  border-color: var(--green);
  color: var(--green);
}

.btn-complete.done {
  background: var(--green-dim);
  border-color: var(--green);
  color: var(--green);
}

/* ── 본문 ── */
.chapter-content {
  max-width: 900px;
  margin: 0 auto;
  padding: 48px 48px 80px;
}

/* ── 챕터 타이틀 ── */
.chapter-title-wrap {
  margin-bottom: 48px;
}

.chapter-num {
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 8px;
  font-family: var(--font-code);
}

.chapter-title {
  font-size: 36px;
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 12px;
}

.chapter-desc {
  font-size: 17px;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* ── 학습목표 카드 ── */
.learning-goals {
  background: var(--accent-dim);
  border: 1px solid rgba(88, 166, 255, .3);
  border-radius: var(--radius-lg);
  padding: 24px;
  margin-bottom: 48px;
}

.learning-goals-title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  font-weight: 700;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 14px;
}

.learning-goals ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.learning-goals li {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 14px;
  color: var(--text-secondary);
}

.learning-goals li::before {
  content: '';
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent);
  flex-shrink: 0;
}

/* ── 섹션 ── */
.section {
  margin-bottom: 56px;
}

.section-title {
  font-size: 22px;
  font-weight: 700;
  margin-bottom: 20px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: 10px;
}

.section-icon {
  font-size: 20px;
}

h3 {
  font-size: 17px;
  font-weight: 600;
  margin: 28px 0 12px;
  color: var(--text-primary);
}

h4 {
  font-size: 15px;
  font-weight: 600;
  margin: 20px 0 8px;
  color: var(--text-secondary);
}

p {
  margin-bottom: 14px;
  color: var(--text-secondary);
  font-size: 15px;
}

p strong {
  color: var(--text-primary);
}

/* ── 코드 블록 ── */
.code-block {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  margin: 16px 0;
  position: relative;
}

.code-block-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 14px;
  background: var(--bg-tertiary);
  border-bottom: 1px solid var(--border);
}

.code-lang {
  font-size: 11px;
  color: var(--text-muted);
  font-family: var(--font-code);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.copy-btn {
  display: flex;
  align-items: center;
  gap: 5px;
  background: none;
  border: 1px solid var(--border);
  border-radius: 4px;
  color: var(--text-muted);
  font-size: 11px;
  padding: 3px 8px;
  cursor: pointer;
  font-family: var(--font-body);
  transition: all var(--transition);
}

.copy-btn:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
}

.copy-btn.copied {
  border-color: var(--green);
  color: var(--green);
}

pre {
  padding: 16px;
  overflow-x: auto;
  font-family: var(--font-code);
  font-size: 14px;
  line-height: 1.65;
}

code {
  font-family: var(--font-code);
  font-size: 13px;
  background: var(--bg-card);
  padding: 2px 6px;
  border-radius: 4px;
  color: var(--accent);
  border: 1px solid var(--border);
}

pre code {
  background: none;
  padding: 0;
  border: none;
  color: var(--text-primary);
  font-size: 14px;
}

/* 터미널 스타일 (Light Theme) */
.code-block.terminal .code-block-header {
  background: #f3f4f6;
  border-bottom-color: #e5e7eb;
}

.code-block.terminal pre {
  background: #f9fafb;
}

.code-block.terminal .prompt {
  color: #059669;
  font-weight: 600;
}

.code-block.terminal .comment {
  color: #6b7280;
  font-style: italic;
}

.code-block.terminal .output {
  color: #374151;
}

.code-block.terminal .copy-btn {
  background: #ffffff;
  border: 1px solid #d1d5db;
  color: #4b5563;
}

.code-block.terminal .copy-btn:hover {
  background: #f3f4f6;
  color: #111827;
}

/* ── 인라인 강조 ── */
.highlight-box {
  border-radius: var(--radius);
  padding: 16px 20px;
  margin: 16px 0;
  font-size: 14px;
  border-left: 3px solid;
}

.highlight-box.info {
  background: var(--accent-dim);
  border-color: var(--accent);
}

.highlight-box.warning {
  background: var(--yellow-dim);
  border-color: var(--yellow);
}

.highlight-box.success {
  background: var(--green-dim);
  border-color: var(--green);
}

.highlight-box.danger {
  background: var(--red-dim);
  border-color: var(--red);
}

.highlight-box .box-title {
  font-weight: 700;
  margin-bottom: 6px;
  font-size: 13px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.highlight-box p {
  margin-bottom: 0;
  color: inherit;
  font-size: 13px;
}

/* ── 비교 테이블 ── */
.compare-table {
  width: 100%;
  border-collapse: collapse;
  margin: 16px 0;
  font-size: 14px;
}

.compare-table th {
  background: var(--bg-tertiary);
  padding: 10px 16px;
  text-align: left;
  font-weight: 600;
  font-size: 13px;
  border-bottom: 1px solid var(--border);
  color: var(--text-secondary);
}

.compare-table td {
  padding: 10px 16px;
  border-bottom: 1px solid var(--border-light);
  color: var(--text-secondary);
}

.compare-table tr:hover td {
  background: var(--bg-hover);
}

.compare-table .key-col {
  color: var(--text-primary);
  font-weight: 500;
}

/* ── 스텝 위저드 ── */
.step-list {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.step-item {
  display: flex;
  gap: 0;
  position: relative;
}

.step-item:not(:last-child) .step-left::after {
  content: '';
  position: absolute;
  left: 50%;
  top: 48px;
  bottom: -16px;
  width: 2px;
  background: var(--border);
  transform: translateX(-50%);
}

.step-left {
  display: flex;
  flex-direction: column;
  align-items: center;
  width: 48px;
  flex-shrink: 0;
  padding-top: 4px;
  position: relative;
  margin-bottom: 16px;
}

.step-num {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--bg-card);
  border: 2px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  font-weight: 700;
  color: var(--text-muted);
  font-family: var(--font-code);
  z-index: 1;
}

.step-item.active .step-num {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.step-item.done .step-num {
  background: var(--green);
  border-color: var(--green);
  color: #fff;
}

.step-body {
  flex: 1;
  padding-bottom: 28px;
}

.step-title {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 8px;
  padding-top: 6px;
}

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

/* ── Git 영역 다이어그램 ── */
.git-diagram {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 24px;
  margin: 24px 0;
  overflow-x: auto;
}

.git-diagram-title {
  text-align: center;
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 20px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.git-areas {
  display: flex;
  align-items: stretch;
  gap: 0;
  min-width: 500px;
}

.git-area {
  flex: 1;
  text-align: center;
  padding: 16px 12px;
  border-radius: var(--radius);
  position: relative;
}

.git-area-wd {
  background: var(--accent-dim);
  border: 1.5px solid var(--wd-color);
}

.git-area-sa {
  background: var(--yellow-dim);
  border: 1.5px solid var(--sa-color);
}

.git-area-lr {
  background: var(--green-dim);
  border: 1.5px solid var(--lr-color);
}

.git-area-rr {
  background: var(--purple-dim);
  border: 1.5px solid var(--rr-color);
}

.git-area-icon {
  font-size: 24px;
  margin-bottom: 6px;
}

.git-area-name {
  font-size: 12px;
  font-weight: 700;
  margin-bottom: 2px;
}

.git-area-name-wd {
  color: var(--wd-color);
}

.git-area-name-sa {
  color: var(--sa-color);
}

.git-area-name-lr {
  color: var(--lr-color);
}

.git-area-name-rr {
  color: var(--rr-color);
}

.git-area-sub {
  font-size: 11px;
  color: var(--text-muted);
}

.git-area-files {
  margin-top: 12px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.git-file {
  background: var(--bg-secondary);
  border-radius: 4px;
  padding: 4px 8px;
  font-size: 11px;
  font-family: var(--font-code);
  color: var(--text-primary);
  border: 1px solid var(--border);
  text-align: left;
  display: flex;
  align-items: center;
  gap: 6px;
}

.git-file.new {
  border-color: var(--green);
  color: var(--green);
}

.git-file.modified {
  border-color: var(--yellow);
  color: var(--yellow);
}

.git-file.staged {
  border-color: var(--sa-color);
}

.git-file.committed {
  border-color: var(--lr-color);
  color: var(--lr-color);
}

.git-arrow {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 0 4px;
  flex-shrink: 0;
  width: 64px;
}

.git-arrow-cmd {
  font-size: 10px;
  font-family: var(--font-code);
  color: var(--text-muted);
  background: var(--bg-secondary);
  padding: 2px 6px;
  border-radius: 3px;
  margin-bottom: 4px;
  white-space: nowrap;
}

.git-arrow-line {
  display: flex;
  align-items: center;
  width: 100%;
}

.git-arrow-line::before {
  content: '';
  flex: 1;
  height: 1.5px;
  background: var(--border);
}

.git-arrow-line::after {
  content: '▶';
  color: var(--text-muted);
  font-size: 10px;
  margin-left: -1px;
}

/* ── 커밋 그래프 ── */
.commit-graph {
  padding: 8px 0;
}

.commit-row {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 2px;
}

.commit-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  border: 2px solid var(--accent);
  background: var(--accent-dim);
  flex-shrink: 0;
  position: relative;
  z-index: 1;
}

.commit-dot.head {
  border-color: var(--yellow);
  background: var(--yellow-dim);
}

.commit-dot.merge {
  border-color: var(--purple);
  background: var(--purple-dim);
}

.commit-line {
  height: 16px;
  width: 2px;
  background: var(--border);
  margin-left: 5px;
  margin-top: -2px;
  margin-bottom: -2px;
}

.commit-info {
  font-size: 13px;
  font-family: var(--font-code);
}

.commit-hash {
  color: var(--yellow);
  font-size: 11px;
}

.commit-msg {
  color: var(--text-primary);
  margin-left: 8px;
}

.commit-tag {
  display: inline-block;
  padding: 1px 6px;
  border-radius: 3px;
  font-size: 10px;
  font-weight: 700;
  margin-left: 6px;
}

.tag-head {
  background: var(--yellow-dim);
  color: var(--yellow);
  border: 1px solid var(--yellow);
}

.tag-main {
  background: var(--accent-dim);
  color: var(--accent);
  border: 1px solid var(--accent);
}

.tag-branch {
  background: var(--green-dim);
  color: var(--green);
  border: 1px solid var(--green);
}

/* ── 브랜치 다이어그램 ── */
.branch-diagram svg {
  width: 100%;
  max-height: 200px;
}

/* ── 경보 박스 ── */
.alert {
  padding: 14px 18px;
  border-radius: var(--radius);
  margin: 16px 0;
  font-size: 14px;
  display: flex;
  gap: 10px;
}

.alert-icon {
  font-size: 16px;
  flex-shrink: 0;
  margin-top: 1px;
}

.alert p {
  margin: 0;
  color: inherit;
  font-size: 14px;
}

.alert.tip {
  background: var(--accent-dim);
  color: var(--accent);
}

.alert.warn {
  background: var(--yellow-dim);
  color: var(--yellow);
}

.alert.danger {
  background: var(--red-dim);
  color: var(--red);
}

.alert.success {
  background: var(--green-dim);
  color: var(--green);
}

/* ── quiz / 체크 ── */
.quiz-section {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 24px;
  margin-top: 40px;
}

.quiz-title {
  font-size: 16px;
  font-weight: 700;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.quiz-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 10px 0;
  border-bottom: 1px solid var(--border-light);
  font-size: 14px;
  color: var(--text-secondary);
  cursor: pointer;
}

.quiz-item:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.quiz-checkbox {
  width: 18px;
  height: 18px;
  min-width: 18px;
  border: 2px solid var(--border);
  border-radius: 4px;
  background: var(--bg-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition);
  margin-top: 2px;
}

.quiz-item.checked .quiz-checkbox {
  background: var(--green);
  border-color: var(--green);
  color: #000;
}

.quiz-item.checked .quiz-checkbox::after {
  content: '✓';
  font-size: 11px;
  font-weight: 700;
}

.quiz-item.checked .quiz-text {
  text-decoration: line-through;
  color: var(--text-muted);
}

/* ── 명령어 치트시트 ── */
.cheatsheet {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 0;
  overflow: hidden;
  margin-top: 40px;
}

.cheatsheet-header {
  background: var(--bg-tertiary);
  padding: 14px 20px;
  border-bottom: 1px solid var(--border);
  font-size: 13px;
  font-weight: 700;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 8px;
}

.cheatsheet-row {
  display: flex;
  align-items: center;
  padding: 10px 20px;
  border-bottom: 1px solid var(--border-light);
  gap: 16px;
}

.cheatsheet-row:last-child {
  border-bottom: none;
}

.cheat-cmd {
  font-family: var(--font-code);
  font-size: 13px;
  color: var(--accent);
  min-width: 220px;
  background: var(--bg-secondary);
  padding: 3px 8px;
  border-radius: 4px;
  border: 1px solid var(--border);
}

.cheat-desc {
  font-size: 13px;
  color: var(--text-secondary);
}

/* ── 네비게이션 ── */
.chapter-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 40px;
  border-top: 1px solid var(--border);
  margin-top: 40px;
}

.nav-btn {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: var(--radius);
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  font-size: 14px;
  text-decoration: none;
  transition: all var(--transition);
}

.nav-btn:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
  text-decoration: none;
}

.nav-btn.next {
  background: var(--accent-dim);
  border-color: var(--accent);
  color: var(--accent);
}

.nav-btn.next:hover {
  background: var(--accent);
  color: #fff;
}

/* ========================================
   인덱스 페이지 전용
   ======================================== */
.index-hero {
  text-align: center;
  padding: 80px 48px 60px;
  background: linear-gradient(180deg, var(--bg-secondary) 0%, transparent 100%);
  border-bottom: 1px solid var(--border);
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--accent-dim);
  border: 1px solid rgba(88, 166, 255, .3);
  border-radius: 20px;
  padding: 5px 14px;
  font-size: 12px;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 24px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.hero-title {
  font-size: 48px;
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: 16px;
  letter-spacing: -1px;
}

.hero-title span {
  color: var(--accent);
}

.hero-desc {
  font-size: 18px;
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto 32px;
}

.hero-meta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 24px;
  flex-wrap: wrap;
}

.hero-stat {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 14px;
  color: var(--text-muted);
}

.hero-stat strong {
  color: var(--text-primary);
}

.chapter-grid {
  padding: 48px;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 16px;
}

.chapter-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 24px;
  text-decoration: none;
  transition: all var(--transition);
  display: flex;
  flex-direction: column;
  gap: 12px;
  position: relative;
  overflow: hidden;
}

.chapter-card::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 3px;
}

.chapter-card.part-1::before {
  background: var(--orange);
}

.chapter-card.part-2::before {
  background: var(--yellow);
}

.chapter-card.part-3::before {
  background: var(--green);
}

.chapter-card.part-4::before {
  background: var(--purple);
}

.chapter-card:hover {
  background: var(--bg-hover);
  border-color: var(--bg-hover);
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  text-decoration: none;
}

.card-num {
  font-size: 12px;
  font-family: var(--font-code);
  color: var(--text-muted);
}

.card-title {
  font-size: 16px;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.3;
}

.card-desc {
  font-size: 13px;
  color: var(--text-muted);
  flex: 1;
}

.card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.card-time {
  font-size: 12px;
  color: var(--text-muted);
}

.card-status {
  font-size: 11px;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 10px;
}

.card-status.done {
  background: var(--green-dim);
  color: var(--green);
}

.card-status.inprog {
  background: var(--yellow-dim);
  color: var(--yellow);
}

.card-status.todo {
  background: var(--bg-hover);
  color: var(--text-muted);
}

.part-divider {
  padding: 0 48px 12px;
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--text-muted);
}

.part-divider::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--border);
}

.part-divider.p1 {
  color: var(--accent);
}

.part-divider.p2 {
  color: var(--yellow);
}

.part-divider.p3 {
  color: var(--green);
}

.part-divider.p4 {
  color: var(--purple);
}

/* ── 모달 ── */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, .85);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition);
  padding: 20px;
}

.modal-overlay.active {
  opacity: 1;
  pointer-events: all;
}

.modal-content {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  max-width: 90vw;
  max-height: 90vh;
  overflow: auto;
  position: relative;
  transform: scale(0.95);
  transition: transform var(--transition);
}

.modal-overlay.active .modal-content {
  transform: scale(1);
}

.modal-close {
  position: absolute;
  top: 12px;
  right: 12px;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--bg-hover);
  border: none;
  cursor: pointer;
  color: var(--text-secondary);
  font-size: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.modal-close:hover {
  background: var(--red-dim);
  color: var(--red);
}

.modal-content img {
  max-width: 80vw;
  max-height: 80vh;
  object-fit: contain;
  padding: 20px;
}

/* ── 반응형 ── */
.menu-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--text-primary);
  font-size: 20px;
  cursor: pointer;
  padding: 4px 8px;
}

@media (max-width: 768px) {
  .sidebar {
    transform: translateX(-100%);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .main-content {
    margin-left: 0;
  }

  .chapter-content {
    padding: 24px;
  }

  .chapter-header {
    padding: 0 16px;
  }

  .git-areas {
    flex-direction: column;
  }

  .git-arrow {
    flex-direction: row;
    width: auto;
    padding: 4px 0;
  }

  .hero-title {
    font-size: 32px;
  }

  .chapter-grid {
    padding: 24px;
  }

  .part-divider {
    padding: 0 24px 12px;
  }

  .menu-toggle {
    display: flex;
  }

  .cheat-cmd {
    min-width: 160px;
  }
}

/* ── 애니메이션 ── */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(12px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulse {

  0%,
  100% {
    opacity: 1;
  }

  50% {
    opacity: 0.5;
  }
}

@keyframes slideRight {
  from {
    transform: translateX(-4px);
    opacity: 0;
  }

  to {
    transform: translateX(0);
    opacity: 1;
  }
}

.animate-in {
  animation: fadeIn 0.4s ease forwards;
}

.file-pulse {
  animation: pulse 1.5s ease infinite;
}

/* ── 인터랙티브 다이어그램 ── */
.diagram-interactive {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  margin: 24px 0;
}

.diagram-tabs {
  display: flex;
  border-bottom: 1px solid var(--border);
  background: var(--bg-tertiary);
  overflow-x: auto;
}

.diagram-tab {
  padding: 10px 20px;
  font-size: 13px;
  font-weight: 500;
  border-bottom: 2px solid transparent;
  cursor: pointer;
  color: var(--text-muted);
  white-space: nowrap;
  transition: all var(--transition);
  background: none;
  border-top: none;
  border-left: none;
  border-right: none;
  font-family: var(--font-body);
}

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

.diagram-tab.active {
  border-bottom-color: var(--accent);
  color: var(--accent);
}

.diagram-panel {
  display: none;
  padding: 24px;
}

.diagram-panel.active {
  display: block;
}

/* ========================================
   실습 섹션 스타일
   ======================================== */

/* ── 실습 섹션 래퍼 ── */
.practice-section {
  background: var(--bg-secondary);
  border: 1.5px solid var(--green);
  border-radius: var(--radius-lg);
  overflow: hidden;
  margin: 40px 0;
}

/* ── 미션 헤더 ── */
.practice-header {
  background: linear-gradient(135deg, rgba(63, 185, 80, .12), rgba(88, 166, 255, .08));
  border-bottom: 1px solid var(--border);
  padding: 24px 28px 20px;
}

.practice-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--green-dim);
  border: 1px solid var(--green);
  border-radius: 20px;
  padding: 3px 12px;
  font-size: 11px;
  font-weight: 700;
  color: var(--green);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 10px;
}

.practice-title {
  font-size: 18px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 6px;
}

.practice-desc {
  font-size: 14px;
  color: var(--text-secondary);
  margin: 0;
}

/* 미션 진행률 */
.mission-progress {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-top: 14px;
}

.mission-progress-bar {
  flex: 1;
  height: 5px;
  background: var(--bg-hover);
  border-radius: 3px;
  overflow: hidden;
}

.mission-progress-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--green), var(--accent));
  border-radius: 3px;
  transition: width 0.4s ease;
}

.mission-progress-label {
  font-size: 12px;
  color: var(--text-muted);
  white-space: nowrap;
}

/* 미션 완료 시 효과 */
.practice-section.mission-complete .practice-header {
  background: linear-gradient(135deg, rgba(63, 185, 80, .2), rgba(63, 185, 80, .08));
}

.practice-section.mission-complete .practice-badge {
  background: var(--green);
  color: #000;
}

/* ── 실습 본문 ── */
.practice-body {
  padding: 24px 28px;
}

/* ── Step 카드 ── */
.practice-step {
  display: grid;
  grid-template-columns: 36px 1fr auto;
  gap: 0 14px;
  margin-bottom: 24px;
  align-items: start;
}

.practice-step:last-of-type {
  margin-bottom: 0;
}

.practice-step-num {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--bg-card);
  border: 2px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  font-weight: 700;
  color: var(--text-muted);
  font-family: var(--font-code);
  flex-shrink: 0;
  transition: all var(--transition);
  margin-top: 2px;
}

.practice-step.step-done .practice-step-num {
  background: var(--green);
  border-color: var(--green);
  color: #000;
}

.practice-step-content {
  min-width: 0;
}

.practice-step-title {
  font-size: 15px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 6px;
}

.practice-step.step-done .practice-step-title {
  text-decoration: line-through;
  color: var(--text-muted);
}

.practice-step-desc {
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 8px;
}

.step-check-btn {
  padding: 5px 12px;
  font-size: 12px;
  font-family: var(--font-body);
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-muted);
  cursor: pointer;
  transition: all var(--transition);
  white-space: nowrap;
  height: fit-content;
  margin-top: 2px;
}

.step-check-btn:hover {
  background: var(--green-dim);
  border-color: var(--green);
  color: var(--green);
}

.step-check-btn.done {
  background: var(--green-dim);
  border-color: var(--green);
  color: var(--green);
}

/* Step 구분선 */
.practice-step+.practice-step {
  padding-top: 24px;
  border-top: 1px solid var(--border-light);
}

/* ── 상태 변화 패널 ── */
.state-panel {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  margin-top: 12px;
}

.state-panel-title {
  padding: 8px 14px;
  background: var(--bg-tertiary);
  border-bottom: 1px solid var(--border);
  font-size: 11px;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.state-panel-title::before {
  content: '🔄';
  font-size: 11px;
}

.state-tabs {
  display: flex;
  border-bottom: 1px solid var(--border);
  background: var(--bg-secondary);
  overflow-x: auto;
}

.state-tab {
  padding: 7px 14px;
  font-size: 12px;
  color: var(--text-muted);
  border-bottom: 2px solid transparent;
  cursor: pointer;
  white-space: nowrap;
  background: none;
  border-top: none;
  border-left: none;
  border-right: none;
  font-family: var(--font-body);
  transition: all var(--transition);
}

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

.state-tab.active {
  border-bottom-color: var(--green);
  color: var(--green);
  font-weight: 600;
}

.state-view {
  display: none;
  padding: 14px;
}

.state-view.active {
  display: block;
}

/* 3영역 미니 다이어그램 (상태 패널용) */
.state-areas {
  display: flex;
  align-items: stretch;
  gap: 6px;
  font-size: 11px;
}

.state-area {
  flex: 1;
  text-align: center;
  padding: 10px 8px;
  border-radius: 6px;
  min-width: 0;
}

.state-area-wd {
  background: var(--accent-dim);
  border: 1px solid var(--wd-color);
}

.state-area-sa {
  background: var(--yellow-dim);
  border: 1px solid var(--sa-color);
}

.state-area-lr {
  background: var(--green-dim);
  border: 1px solid var(--lr-color);
}

.state-area-name {
  font-size: 10px;
  font-weight: 700;
  margin-bottom: 6px;
}

.state-area-name-wd {
  color: var(--wd-color);
}

.state-area-name-sa {
  color: var(--sa-color);
}

.state-area-name-lr {
  color: var(--lr-color);
}

.state-file {
  font-family: var(--font-code);
  font-size: 10px;
  background: var(--bg-secondary);
  border-radius: 3px;
  padding: 3px 5px;
  margin-top: 3px;
  text-align: left;
  display: flex;
  align-items: center;
  gap: 3px;
  border: 1px solid var(--border);
}

.state-file.untracked {
  color: var(--red);
  border-color: var(--red);
}

.state-file.staged {
  color: var(--sa-color);
  border-color: var(--sa-color);
}

.state-file.modified {
  color: var(--yellow);
  border-color: var(--yellow);
}

.state-file.committed {
  color: var(--lr-color);
  border-color: var(--lr-color);
}

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

.state-arrow {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  padding: 0 2px;
}

.state-arrow-cmd {
  font-size: 9px;
  font-family: var(--font-code);
  color: var(--text-muted);
  background: var(--bg-secondary);
  padding: 1px 4px;
  border-radius: 2px;
  margin-bottom: 2px;
  white-space: nowrap;
}

.state-arrow::after {
  content: '▶';
  color: var(--text-muted);
  font-size: 9px;
}

.state-empty {
  font-size: 10px;
  color: var(--text-muted);
  margin-top: 4px;
}

.state-next-hint {
  margin-top: 8px;
  padding: 6px 10px;
  background: var(--accent-dim);
  border-radius: 5px;
  font-size: 11px;
  color: var(--accent);
  font-family: var(--font-code);
}

.state-next-hint::before {
  content: '→ 다음: ';
  color: var(--text-muted);
}

/* ── 시나리오 카드 ── */
.scenarios-wrap {
  margin-top: 28px;
  padding-top: 24px;
  border-top: 1px solid var(--border);
}

.scenarios-title {
  font-size: 14px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.scenario-card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  margin-bottom: 8px;
}

.scenario-header {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 16px;
  background: var(--bg-card);
  cursor: pointer;
  transition: background var(--transition);
  user-select: none;
}

.scenario-header:hover {
  background: var(--bg-hover);
}

.scenario-icon {
  font-size: 16px;
  flex-shrink: 0;
}

.scenario-question {
  font-size: 13px;
  color: var(--text-primary);
  flex: 1;
  font-weight: 500;
}

.scenario-toggle-icon {
  font-size: 10px;
  color: var(--text-muted);
  flex-shrink: 0;
}

.scenario-body {
  padding: 16px 18px;
  background: var(--bg-secondary);
}

.scenario-cause {
  font-size: 12px;
  color: var(--text-muted);
  margin-bottom: 10px;
  display: flex;
  gap: 6px;
}

.scenario-cause::before {
  content: '🔍 원인:';
  font-weight: 600;
  color: var(--yellow);
  white-space: nowrap;
}

.scenario-fix {
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 0;
  display: flex;
  gap: 6px;
  align-items: flex-start;
}

.scenario-fix::before {
  content: '✅ 해결:';
  font-weight: 600;
  color: var(--green);
  white-space: nowrap;
}

/* ── 실습 완료 배너 ── */
.practice-complete-banner {
  display: none;
  margin-top: 20px;
  background: var(--green-dim);
  border: 1px solid var(--green);
  border-radius: var(--radius);
  padding: 14px 18px;
  color: var(--green);
  font-weight: 600;
  font-size: 14px;
  text-align: center;
}

.practice-section.mission-complete .practice-complete-banner {
  display: block;
}