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

:root {
  --primary: #3DBB6E;
  --primary-dark: #2A9D55;
  --text-primary: #111827;
  --text-secondary: #6B7280;
  --bg-page: #FFFFFF;
  --bg-subtle: #F5F7F6;
  --border: #E5E7EB;
  --sidebar-width: 240px;
  --toc-width: 200px;
  --header-height: 64px;
  --content-max: 640px;
}

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  font-size: 15px;
  line-height: 1.65;
  color: var(--text-primary);
  background: var(--bg-page);
  -webkit-font-smoothing: antialiased;
}

a { color: var(--primary-dark); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ── Header ── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-height);
  background: var(--bg-page);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 32px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 18px;
  color: var(--text-primary);
  text-decoration: none;
}
.logo:hover { text-decoration: none; }
.logo svg { flex-shrink: 0; }

.header-nav {
  display: flex;
  align-items: center;
  gap: 28px;
}

.header-nav a {
  font-size: 14px;
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
}
.header-nav a:hover { color: var(--text-primary); }
.header-nav a.active { color: var(--text-primary); font-weight: 600; }

.btn-cta {
  display: inline-flex;
  align-items: center;
  padding: 10px 20px;
  background: var(--primary);
  color: #fff !important;
  font-size: 14px;
  font-weight: 600;
  border-radius: 8px;
  text-decoration: none;
  transition: background 0.15s;
}
.btn-cta:hover {
  background: var(--primary-dark);
  text-decoration: none;
}

/* ── Hero ── */
.hero {
  max-width: calc(var(--sidebar-width) + var(--content-max) + var(--toc-width) + 96px);
  margin: 0 auto;
  padding: 48px 32px 32px;
}

.hero h1 {
  font-size: 36px;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 8px;
}

.hero-subtitle {
  font-size: 16px;
  color: var(--text-secondary);
  max-width: 520px;
  line-height: 1.6;
  margin-bottom: 8px;
}

.hero-date {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 16px;
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  color: var(--text-secondary);
}
.breadcrumb a { color: var(--text-secondary); }
.breadcrumb a:hover { color: var(--primary-dark); }

/* ── Mobile TOC ── */
.mobile-toc {
  display: none;
  max-width: calc(var(--content-max) + 64px);
  margin: 0 auto 24px;
  padding: 0 32px;
}

.mobile-toc select {
  width: 100%;
  padding: 12px 16px;
  font-family: inherit;
  font-size: 14px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg-page);
  color: var(--text-primary);
}

/* ── Three-column layout ── */
.layout {
  display: grid;
  grid-template-columns: var(--sidebar-width) 1fr var(--toc-width);
  gap: 48px;
  max-width: calc(var(--sidebar-width) + var(--content-max) + var(--toc-width) + 96px);
  margin: 0 auto;
  padding: 0 32px 80px;
}

.layout-no-toc {
  grid-template-columns: var(--sidebar-width) 1fr;
  max-width: calc(var(--sidebar-width) + var(--content-max) + 96px);
}

/* Left sidebar */
.sidebar-left {
  position: sticky;
  top: calc(var(--header-height) + 24px);
  align-self: start;
  max-height: calc(100vh - var(--header-height) - 48px);
  overflow-y: auto;
}

.sidebar-group { margin-bottom: 28px; }

.sidebar-group-title {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text-secondary);
  margin-bottom: 12px;
}

.sidebar-link {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 0;
  font-size: 14px;
  color: var(--text-secondary);
  text-decoration: none;
}
.sidebar-link:hover { color: var(--text-primary); text-decoration: none; }
.sidebar-link.active {
  color: var(--primary-dark);
  font-weight: 600;
}

.sidebar-link svg {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  opacity: 0.6;
}
.sidebar-link.active svg { opacity: 1; }

/* Main content */
.content {
  max-width: var(--content-max);
}

.disclaimer {
  background: var(--bg-subtle);
  border-left: 3px solid var(--primary);
  padding: 16px 20px;
  border-radius: 0 8px 8px 0;
  margin-bottom: 32px;
  font-size: 14px;
  color: var(--text-secondary);
}

.intro {
  font-size: 16px;
  color: var(--text-secondary);
  margin-bottom: 40px;
  line-height: 1.7;
}

.content section {
  margin-bottom: 36px;
  scroll-margin-top: calc(var(--header-height) + 16px);
}

.content h2 {
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 12px;
  letter-spacing: -0.01em;
}

.content h3 {
  font-size: 16px;
  font-weight: 600;
  margin: 20px 0 8px;
  color: var(--text-primary);
}

.content p {
  margin-bottom: 12px;
  color: var(--text-secondary);
}

.content ul {
  margin: 8px 0 12px 20px;
  color: var(--text-secondary);
}

.content li { margin-bottom: 6px; }

.content strong {
  color: var(--text-primary);
  font-weight: 600;
}

.contact-email {
  font-weight: 600;
  color: var(--primary-dark);
}

/* Right TOC */
.sidebar-right {
  position: sticky;
  top: calc(var(--header-height) + 24px);
  align-self: start;
}

.toc-title {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 16px;
}

.toc-list { list-style: none; }
.toc-list li { margin-bottom: 4px; }

.toc-list a {
  display: block;
  font-size: 13px;
  color: var(--text-secondary);
  padding: 4px 0;
  text-decoration: none;
  line-height: 1.4;
  transition: color 0.15s;
}
.toc-list a:hover { color: var(--text-primary); text-decoration: none; }
.toc-list a.active {
  color: var(--primary-dark);
  font-weight: 600;
}

.toc-list .toc-sub { padding-left: 14px; }
.toc-list .toc-sub a { font-size: 12px; }

/* ── Home landing ── */
.landing-hero {
  max-width: 960px;
  margin: 0 auto;
  padding: 64px 32px 48px;
  text-align: center;
}

.landing-hero h1 {
  font-size: 44px;
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: 16px;
  line-height: 1.15;
}

.landing-hero p {
  font-size: 18px;
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto 32px;
  line-height: 1.6;
}

.landing-hero .btn-row {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  padding: 10px 20px;
  background: var(--bg-subtle);
  color: var(--text-primary) !important;
  font-size: 14px;
  font-weight: 600;
  border-radius: 8px;
  border: 1px solid var(--border);
  text-decoration: none;
  transition: background 0.15s;
}
.btn-secondary:hover {
  background: var(--border);
  text-decoration: none;
}

.features {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 32px 80px;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.feature-card {
  background: var(--bg-subtle);
  border-radius: 16px;
  padding: 28px;
  border: 1px solid var(--border);
}

.feature-icon {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  background: rgba(61, 187, 110, 0.15);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
  color: var(--primary-dark);
}

.feature-card h3 {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 8px;
}

.feature-card p {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.6;
  margin: 0;
}

/* ── Get app page ── */
.download-card {
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 32px;
  text-align: center;
  margin-bottom: 32px;
}

.download-card .store-badge {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  padding: 14px 28px;
  background: var(--text-primary);
  color: #fff !important;
  border-radius: 12px;
  font-size: 15px;
  font-weight: 600;
  text-decoration: none;
  margin-top: 8px;
  transition: opacity 0.15s;
}
.download-card .store-badge:hover {
  opacity: 0.88;
  text-decoration: none;
}

.download-card .store-badge svg {
  width: 24px;
  height: 24px;
}

.package-name {
  font-family: ui-monospace, monospace;
  font-size: 13px;
  color: var(--text-secondary);
  margin-top: 16px;
}

.info-grid {
  display: grid;
  gap: 16px;
  margin-top: 24px;
}

.info-item {
  display: flex;
  gap: 14px;
  padding: 16px;
  background: var(--bg-page);
  border: 1px solid var(--border);
  border-radius: 12px;
}

.info-item strong {
  display: block;
  font-size: 14px;
  margin-bottom: 4px;
}

.info-item span {
  font-size: 13px;
  color: var(--text-secondary);
}

/* ── FAQ (support) ── */
.faq-item {
  border-bottom: 1px solid var(--border);
  padding: 20px 0;
}
.faq-item:first-child { padding-top: 0; }
.faq-item:last-child { border-bottom: none; }

.faq-item h3 {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--text-primary);
}

.faq-item p {
  font-size: 14px;
  color: var(--text-secondary);
  margin: 0;
  line-height: 1.6;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 32px;
  text-align: center;
  font-size: 13px;
  color: var(--text-secondary);
}

.site-footer a {
  color: var(--text-secondary);
  margin: 0 12px;
}
.site-footer a:hover { color: var(--primary-dark); }

/* ── Responsive ── */
@media (max-width: 1024px) {
  .layout,
  .layout-no-toc {
    grid-template-columns: 1fr;
    gap: 0;
  }
  .sidebar-left,
  .sidebar-right { display: none; }
  .mobile-toc { display: block; }
  .content { max-width: 100%; }
  .features { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  .site-header { padding: 0 16px; }
  .header-nav .nav-link-home { display: none; }
  .hero { padding: 32px 16px 24px; }
  .hero h1 { font-size: 28px; }
  .landing-hero { padding: 40px 16px 32px; }
  .landing-hero h1 { font-size: 32px; }
  .layout { padding: 0 16px 60px; }
  .layout-no-toc { padding: 0 16px 60px; }
  .mobile-toc { padding: 0 16px; }
  .features { padding: 0 16px 60px; }
}