:root {
  /* accent (테마 공통) */
  --primary: #008986;
  --primary-dark: #006f6c;
  --success: #4CAF50;
  --warning: #FF9800;
  --error: #FF5252;
  --strava: #FC4C02;
  /* 라이트 테마 기본값 — 브라우저(prefers-color-scheme)를 따른다 */
  --bg: #ffffff;
  --surface: #f6f7f9;
  --surface2: #eceef1;
  --text: #1f2328;
  --text2: #656d76;
  --border: #d0d7de;
  --heading: #0d1117;
  --sidebar-bg: #f6f7f9;
  --topbar-bg: rgba(255,255,255,0.85);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #121212;
    --surface: #1E1E1E;
    --surface2: #2A2A2A;
    --text: #E0E0E0;
    --text2: #9E9E9E;
    --border: #333;
    --heading: #ffffff;
    --sidebar-bg: #161616;
    --topbar-bg: rgba(18,18,18,0.85);
  }
}

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

body {
  font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  scroll-behavior: smooth;
}

/* -- Header -- */
header {
  background: linear-gradient(135deg, #063f43 0%, #006f6c 52%, #008986 100%);
  padding: 60px 20px 40px;
  text-align: center;
  position: relative;
  overflow: hidden;
}
header::after {
  content: '';
  position: absolute;
  bottom: 0; left: 0; right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--primary), var(--success), var(--warning), var(--error));
}
header h1 {
  font-size: 2.4rem;
  font-weight: 800;
  letter-spacing: -0.5px;
  margin-bottom: 8px;
}
header .subtitle {
  color: rgba(255,255,255,0.7);
  font-size: 1rem;
}
header .version {
  display: inline-block;
  margin-top: 12px;
  padding: 4px 14px;
  border-radius: 20px;
  background: rgba(255,255,255,0.15);
  font-size: 0.85rem;
  color: rgba(255,255,255,0.8);
}

/* -- Layout -- */
.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 20px;
}

/* -- TOC -- */
#toc {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  margin: 30px auto;
  padding: 28px 32px;
  max-width: 900px;
}
#toc h2 {
  font-size: 1.3rem;
  margin-bottom: 16px;
  color: var(--primary);
}
#toc ol {
  list-style: none;
  counter-reset: toc;
}
#toc > ol > li {
  counter-increment: toc;
  margin-bottom: 6px;
}
#toc > ol > li::before {
  content: counter(toc) ". ";
  color: var(--primary);
  font-weight: 700;
}
#toc a {
  color: var(--text);
  text-decoration: none;
  transition: color 0.2s;
}
#toc a:hover { color: var(--primary); }
#toc .sub {
  list-style: none;
  padding-left: 24px;
  margin-top: 4px;
}
#toc .sub li { margin-bottom: 3px; }
#toc .sub li::before {
  content: "\2013 ";
  color: var(--text2);
}

/* -- Sections -- */
section {
  margin: 40px auto;
  max-width: 900px;
}
section > h2 {
  font-size: 1.6rem;
  font-weight: 800;
  padding: 12px 0;
  margin-bottom: 20px;
  border-bottom: 3px solid var(--primary);
  color: var(--heading);
}
h3 {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--primary);
  margin: 28px 0 12px;
}
h4 {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--success);
  margin: 20px 0 8px;
}

p { margin-bottom: 12px; }

/* -- Cards -- */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 20px 24px;
  margin-bottom: 16px;
}
.card h4 { margin-top: 0; }

/* -- Tables -- */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 12px 0 20px;
  font-size: 0.92rem;
}
th, td {
  padding: 10px 14px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}
th {
  background: var(--surface2);
  color: var(--primary);
  font-weight: 700;
  white-space: nowrap;
}
td { color: var(--text); }
tr:hover td { background: color-mix(in oklab, var(--primary) 5%, transparent); }

/* -- Lists -- */
ul, ol { padding-left: 24px; margin-bottom: 12px; }
li { margin-bottom: 4px; }

/* -- Tags / Badges -- */
.tag {
  display: inline-block;
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.78rem;
  font-weight: 600;
  vertical-align: middle;
}
.tag-login    { background: #064e3b; color: #a7f3d0; }
.tag-strava   { background: #bf360c; color: #ffab91; }
.tag-map      { background: #01579b; color: #81d4fa; }
.tag-power    { background: #4a148c; color: #ce93d8; }

/* -- Keyboard / Shortcut -- */
kbd {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 4px;
  background: var(--surface2);
  border: 1px solid var(--border);
  font-family: monospace;
  font-size: 0.85rem;
}

/* -- Tip / Warning boxes -- */
.tip, .warn, .info {
  border-radius: 8px;
  padding: 14px 18px;
  margin: 14px 0;
  font-size: 0.93rem;
}
.tip {
  background: rgba(76,175,80,0.1);
  border-left: 4px solid var(--success);
}
.warn {
  background: rgba(255,152,0,0.1);
  border-left: 4px solid var(--warning);
}
.info {
  background: color-mix(in oklab, var(--primary) 10%, transparent);
  border-left: 4px solid var(--primary);
}

/* -- Quick Start -- */
.quick-start {
  background: linear-gradient(135deg, color-mix(in oklab, var(--primary) 8%, transparent), rgba(76,175,80,0.08));
  border: 1px solid var(--primary);
  border-radius: 12px;
  padding: 28px 32px;
  margin: 30px auto;
  max-width: 900px;
}
.quick-start h2 {
  font-size: 1.4rem;
  color: var(--primary);
  margin-bottom: 16px;
  border-bottom: none;
  padding: 0;
}
.quick-start .step {
  display: flex;
  align-items: flex-start;
  margin-bottom: 16px;
  gap: 14px;
}
.quick-start .step-num {
  flex-shrink: 0;
  width: 32px;
  height: 32px;
  background: var(--primary);
  color: var(--heading);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 0.9rem;
}
.quick-start .step-content {
  flex: 1;
}
.quick-start .step-content strong {
  color: var(--heading);
}

/* -- Back to top -- */
.back-top {
  display: block;
  text-align: right;
  margin-top: 16px;
  font-size: 0.85rem;
}
.back-top a {
  color: var(--text2);
  text-decoration: none;
}
.back-top a:hover { color: var(--primary); }

/* -- Footer -- */
footer {
  text-align: center;
  padding: 40px 20px;
  color: var(--text2);
  font-size: 0.85rem;
  border-top: 1px solid var(--border);
  margin-top: 60px;
}
footer a {
  color: var(--primary);
  text-decoration: none;
}

/* -- Chapter Nav Bar -- */
.chapter-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 10px 20px;
  position: sticky;
  top: 0;
  z-index: 100;
  font-size: 0.9rem;
}
.chapter-nav a {
  color: var(--primary);
  text-decoration: none;
  white-space: nowrap;
}
.chapter-nav a:hover {
  text-decoration: underline;
}
.chapter-nav .nav-title {
  color: var(--text);
  font-weight: 700;
  text-align: center;
  flex: 1;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  padding: 0 12px;
}
.chapter-nav .nav-left,
.chapter-nav .nav-right {
  flex-shrink: 0;
  min-width: 60px;
}
.chapter-nav .nav-right {
  text-align: right;
}
.chapter-nav .nav-sep {
  color: var(--text2);
  margin: 0 6px;
}

/* -- Bottom Nav -- */
.bottom-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--surface);
  border-top: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px 20px;
  margin: 40px 0 0;
  font-size: 0.9rem;
}
.bottom-nav a {
  color: var(--primary);
  text-decoration: none;
}
.bottom-nav a:hover {
  text-decoration: underline;
}
.bottom-nav .nav-title {
  color: var(--text2);
  text-align: center;
  flex: 1;
}

/* -- TOC Cards (Index page) -- */
.toc-cards {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
  margin: 24px 0;
}
.toc-card {
  display: flex;
  align-items: center;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px 20px;
  text-decoration: none;
  color: var(--text);
  transition: border-color 0.2s, background 0.2s;
  gap: 16px;
}
.toc-card:hover {
  border-color: var(--primary);
  background: color-mix(in oklab, var(--primary) 5%, transparent);
}
.toc-card .ch-num {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  background: var(--primary);
  color: var(--heading);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 1rem;
}
.toc-card .ch-info {
  flex: 1;
  min-width: 0;
}
.toc-card .ch-title {
  font-weight: 700;
  font-size: 1rem;
  color: var(--heading);
  margin-bottom: 2px;
}
.toc-card .ch-desc {
  font-size: 0.85rem;
  color: var(--text2);
}

.manual-store-links {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 24px 0 8px;
  padding: 16px 20px;
}

.manual-store-links span {
  color: var(--text2);
  flex: 1 1 100%;
  font-size: 0.9rem;
  font-weight: 700;
}

.manual-store-links a {
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--heading);
  font-weight: 800;
  min-height: 40px;
  padding: 8px 12px;
  text-decoration: none;
}

.manual-store-links a:hover {
  border-color: var(--primary);
  color: var(--primary);
}

/* -- Level badges -- */
.level {
  display: inline-block;
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.75rem;
  font-weight: 700;
  vertical-align: middle;
  margin-left: 8px;
}
.level-beginner { background: #1b5e20; color: #a5d6a7; }
.level-intermediate { background: #e65100; color: #ffcc80; }
.level-advanced { background: #4a148c; color: #ce93d8; }

/* -- Purpose block -- */
.purpose {
  background: linear-gradient(135deg, color-mix(in oklab, var(--primary) 6%, transparent), color-mix(in oklab, var(--primary) 2%, transparent));
  border: 1px solid color-mix(in oklab, var(--primary) 30%, transparent);
  border-radius: 10px;
  padding: 20px 24px;
  margin: 16px 0 24px;
}
.purpose h4 {
  color: var(--primary);
  margin: 0 0 8px;
  font-size: 1rem;
}
.purpose p {
  margin: 0;
  color: var(--text);
}

/* -- Flow steps -- */
.flow {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  margin: 16px 0;
  font-size: 0.9rem;
}
.flow .flow-step {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 8px 14px;
  font-weight: 600;
  color: var(--text);
}
.flow .flow-arrow {
  color: var(--primary);
  font-size: 1.1rem;
}

/* -- Responsive -- */
@media (max-width: 600px) {
  header { padding: 40px 16px 28px; }
  header h1 { font-size: 1.8rem; }
  #toc { padding: 20px; }
  .quick-start { padding: 20px; }
  .card { padding: 16px; }
  table { font-size: 0.82rem; }
  th, td { padding: 8px 10px; }
  .chapter-nav { padding: 8px 12px; font-size: 0.82rem; }
  .toc-card { padding: 12px 14px; }
}