/* Original lesson-specific/demo styles extracted from flex/flex-lecture.html; consolidate after visual QA. */

:root{
  --bg: var(--page);
  --card: var(--panel);
  --primary: var(--primary-ui);
  --primary-light: var(--primary-ui-pale);
  --primary-dark: var(--primary-ui-hover);
  --text: var(--ink);
  --sub: var(--ink-sub);
  --muted: var(--ink-muted);
  --border: var(--line);
  --code-bg: #1e1e2e;
  --radius: 12px;
  --green: #10b981;
  --amber: #f59e0b;
  --blue: #4361ee;
}
body {
  font-family: 'Segoe UI', 'Noto Sans KR', sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

/* 사이드바 */
.sidebar {
  position: fixed;
  left: 0; top: 0; bottom: 0;
  width: 220px;
  background: var(--card);
  border-right: 1px solid var(--border);
  padding: 24px 0;
  overflow-y: auto;
  z-index: 100;
  transition: transform 0.3s ease;
}
.sidebar.collapsed { transform: translateX(-220px); }
.sidebar-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 0 20px 16px;
  border-bottom: 1px solid var(--border); margin-bottom: 12px;
}
.sidebar-title { font-size: 13px; font-weight: 700; color: var(--primary-dark); letter-spacing: 0.05em; }
.sidebar-toggle { display: none; background: none; border: none; cursor: pointer; font-size: 18px; color: var(--sub); padding: 2px; line-height: 1; }
.nav-home {
  display: flex; align-items: center; gap: 8px;
  padding: 8px 20px 12px; font-size: 12px; font-weight: 600;
  color: var(--primary); text-decoration: none;
  border-bottom: 1px solid var(--border); margin-bottom: 8px; transition: all 0.15s;
}
.nav-home:hover { background: var(--primary-light); }
.nav-home-icon { font-size: 14px; }
.nav-item {
  display: block; padding: 8px 20px;
  font-size: 13px; color: var(--sub);
  text-decoration: none; transition: all 0.15s;
  border-left: 3px solid transparent;
}
.nav-item:hover { color: var(--primary); background: var(--primary-light); }
.nav-item.active { color: var(--primary); border-left-color: var(--primary); background: var(--primary-light); font-weight: 600; }
.nav-num { font-family: monospace; font-size: 11px; color: var(--muted); margin-right: 6px; }
.menu-btn {
  display: none; position: fixed; top: 12px; left: 12px; z-index: 200;
  background: var(--primary); color: #fff; border: none; border-radius: 8px;
  width: 40px; height: 40px; font-size: 18px; cursor: pointer;
  align-items: center; justify-content: center;
  box-shadow: 0 2px 8px rgba(0,0,0,0.15); transition: all 0.15s;
}
.menu-btn:hover { opacity: 0.85; }
.sidebar-overlay { display: none; position: fixed; inset: 0; background: rgba(0,0,0,0.3); z-index: 99; backdrop-filter: blur(2px); }
.sidebar-overlay.show { display: block; }

/* 메인 */
.main { margin-left: 220px; padding: 40px 40px 100px; max-width: 960px; transition: margin 0.3s; }

@media (max-width: 768px) {
  .sidebar { transform: translateX(-220px); }
  .sidebar.open { transform: translateX(0); }
  .menu-btn { display: flex; }
  .sidebar-toggle { display: block; }
  .main { margin-left: 0; padding: 60px 16px 80px; }
}

/* 히어로 */
.hero {
  text-align: center;
  padding: 60px 20px 48px;
  background: linear-gradient(135deg, #f72585 0%, #7209b7 100%);
  border-radius: var(--radius);
  color: #fff;
  margin-bottom: 48px;
}
.hero h1 { font-size: 36px; font-weight: 800; margin-bottom: 12px; letter-spacing: -1px; }
.hero p  { font-size: 16px; opacity: 0.85; }
.hero-badges { display: flex; gap: 8px; justify-content: center; margin-top: 20px; flex-wrap: wrap; }
.hero-badge {
  background: rgba(255,255,255,0.2);
  border: 1px solid rgba(255,255,255,0.3);
  color: #fff; font-size: 12px;
  padding: 4px 12px; border-radius: 20px; font-weight: 500;
}

/* 섹션 */
.section { margin-bottom: 64px; scroll-margin-top: 24px; }
.section-num { font-size: 12px; font-weight: 700; color: var(--primary); letter-spacing: 0.1em; margin-bottom: 6px; }
.section-title { font-size: 26px; font-weight: 800; color: var(--text); margin-bottom: 8px; letter-spacing: -0.5px; }
.section-desc { font-size: 14px; color: var(--sub); line-height: 1.7; }

/* 카드 */
.card {
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); overflow: hidden; margin-bottom: 20px;
}
.card-title {
  font-size: 13px; font-weight: 600; color: var(--sub);
  padding: 12px 16px; border-bottom: 1px solid var(--border);
  background: var(--bg); display: flex; align-items: center; gap: 8px;
}
.dot { width: 8px; height: 8px; border-radius: 50%; }
.dot-pink  { background: var(--primary); }
.dot-green { background: var(--green); }
.dot-amber { background: var(--amber); }

/* 코드 */
.code-block {
  background: var(--code-bg); padding: 20px;
  font-family: 'Fira Code', 'Courier New', monospace;
  font-size: 13px; color: #cdd6f4; line-height: 2; overflow-x: auto;
}
.code-block .cm   { color: #6c7086; }
.code-block .sel  { color: #cba6f7; }
.code-block .prop { color: #89b4fa; }
.code-block .val  { color: #a6e3a1; }
.code-block .str  { color: #f38ba8; }

/* 프리뷰 */
.preview { padding: 20px; background: #f1f5f9; min-height: 80px; }
.preview-label { font-size: 11px; color: var(--muted); font-weight: 600; letter-spacing: 0.08em; margin-bottom: 12px; }

/* flex 데모 박스 */
.flex-demo {
  background: #dbeafe;
  border: 2px solid #93c5fd;
  border-radius: 8px;
  padding: 8px;
  display: flex;
  transition: all 0.3s;
  min-height: 120px;
}
.fi {
  background: var(--primary-light);
  border: 1.5px solid #f9a8d4;
  border-radius: 6px;
  display: flex; align-items: center; justify-content: center;
  font-size: 12px; font-weight: 600; color: var(--primary-dark);
  padding: 8px 12px; transition: all 0.3s;
  white-space: nowrap;
}
.fi.tall { padding: 24px 12px; }
.fi.taller { padding: 40px 12px; }
.fi.wide { min-width: 100px; }

/* 컨트롤 */
.controls {
  padding: 16px 20px; border-top: 1px solid var(--border);
  background: var(--card); display: flex; flex-wrap: wrap; gap: 14px; align-items: center;
}
.ctrl-group { display: flex; align-items: center; gap: 10px; }
.ctrl-label { font-size: 12px; color: var(--sub); font-weight: 500; min-width: 90px; }
.ctrl-group select {
  font-size: 12px; padding: 5px 8px; border-radius: 6px;
  border: 1px solid var(--border); background: var(--card);
  color: var(--text); font-family: inherit;
}
.ctrl-group input[type=range] { width: 100px; accent-color: var(--primary); }
.ctrl-val { font-size: 12px; font-family: monospace; font-weight: 600; color: var(--primary); min-width: 36px; }
.tab-btns { display: flex; gap: 6px; flex-wrap: wrap; }
.tab-btn {
  font-size: 12px; padding: 5px 12px; border-radius: 20px;
  border: 1px solid var(--border); background: var(--card);
  color: var(--sub); cursor: pointer; transition: all 0.15s; font-weight: 500;
}
.tab-btn.active { background: var(--primary); color: #fff; border-color: var(--primary); }

/* 팁 */
.tip {
  border-left: 3px solid var(--primary); background: var(--primary-light);
  padding: 12px 16px; border-radius: 0 8px 8px 0;
  font-size: 13px; color: var(--primary-dark); margin-top: 16px; line-height: 1.7;
}
.tip.green { border-color: var(--green); background: #d1fae5; color: #065f46; }
.tip.amber { border-color: var(--amber); background: #fef3c7; color: #92400e; }
.tip.blue  { border-color: var(--blue); background: #eef2ff; color: #3730a3; }

/* 비교 */
.compare { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-bottom: 16px; }
.compare-card { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
.compare-title { font-size: 12px; font-weight: 600; padding: 10px 14px; border-bottom: 1px solid var(--border); background: var(--bg); }

/* 피그마 비교 배지 */
.figma-badge {
  display: inline-flex; align-items: center; gap: 6px;
  background: #1e1e1e; color: #fff;
  font-size: 11px; padding: 3px 10px;
  border-radius: 20px; font-weight: 500; margin-left: 8px;
}

.divider { border: none; border-top: 1px solid var(--border); margin: 32px 0; }
.badge {
  display: inline-block; font-size: 11px; padding: 2px 8px;
  border-radius: 20px; font-weight: 600; margin-left: 6px;
}
.badge-pink  { background: var(--primary-light); color: var(--primary-dark); }
.badge-green { background: #d1fae5; color: #065f46; }
.badge-blue  { background: #eef2ff; color: #3730a3; }

/* grow/shrink/basis 시각화 */
.grow-demo {
  background: #dbeafe; border: 2px solid #93c5fd;
  border-radius: 8px; padding: 8px;
  display: flex; gap: 8px; min-height: 60px; align-items: stretch;
}
.grow-item {
  border-radius: 6px; display: flex; align-items: center; justify-content: center;
  font-size: 11px; font-weight: 600; color: #fff; transition: all 0.3s; padding: 8px 4px;
  text-align: center; line-height: 1.4;
}

/* 실습 */
.demo-golf {
  display: flex; column-gap: 16px;
}
.demo-golf .gi {
  flex: 1; background: #f0fdf4; border: 1px solid #86efac;
  border-radius: 8px; padding: 12px; font-size: 12px; font-weight: 600; color: #065f46;
}
.demo-pintel {
  display: flex; gap: 16px; align-items: stretch;
}
.demo-pintel .pi-txt {
  flex: 0 0 200px; background: #1e1e2e; color: #cdd6f4; border-radius: 8px; padding: 20px; font-size: 13px;
}
.demo-pintel .pi-list {
  flex: 1; display: flex; flex-direction: column; gap: 10px;
}
.demo-pintel .pi-item {
  flex: 1; background: #f8f9fc; border: 1px solid var(--border);
  border-radius: 8px; padding: 14px; font-size: 12px; font-weight: 600; color: var(--sub);
}