:root {
  --color-page: #f8fafc;
  --color-surface: #ffffff;
  --color-ink: #0f172a;
  --color-muted: #64748b;
  --color-border: #e2e8f0;
  --color-primary: #2563eb;
  --color-primary-strong: #1d4ed8;
  --color-success: #16a34a;
  --color-warning: #f59e0b;
  --color-danger: #dc2626;
  --color-code: #111827;
  --shadow-soft: 0 12px 30px rgba(15, 23, 42, 0.08);
  --radius: 8px;
  --font-sans: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  --container: 1120px;
}

* {
  box-sizing: border-box;
}

html {
  min-width: 320px;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--color-page);
  color: var(--color-ink);
  font-family: var(--font-sans);
  line-height: 1.5;
}

body[data-require-auth]:not([data-auth-ready="true"]) .app-shell,
body[data-require-auth]:not([data-auth-ready="true"]) #admin-app {
  visibility: hidden;
}

a {
  color: inherit;
  text-decoration: none;
}

button,
input,
select,
textarea {
  font: inherit;
}

.container {
  width: min(100% - 40px, var(--container));
  margin-inline: auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(248, 250, 252, 0.92);
  border-bottom: 1px solid var(--color-border);
  backdrop-filter: blur(14px);
}

.nav {
  position: relative;
  display: flex;
  min-height: 68px;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
}

.brand-mark {
  display: grid;
  width: 34px;
  height: 34px;
  place-items: center;
  border-radius: var(--radius);
  background: var(--color-ink);
  color: #ffffff;
  font-size: 13px;
  letter-spacing: 0;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 22px;
  color: var(--color-muted);
  font-size: 14px;
  font-weight: 600;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.mobile-menu-button {
  display: none;
}

.button {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border: 1px solid transparent;
  border-radius: var(--radius);
  padding: 0 16px;
  cursor: pointer;
  font-size: 14px;
  font-weight: 700;
  transition: background 160ms ease, border-color 160ms ease, color 160ms ease, transform 160ms ease;
}

.button:hover {
  transform: translateY(-1px);
}

.button-primary {
  background: var(--color-primary);
  color: #ffffff;
}

.button-primary:hover {
  background: var(--color-primary-strong);
}

.button-secondary {
  border-color: var(--color-border);
  background: var(--color-surface);
  color: var(--color-ink);
}

.hero {
  padding: 84px 0 44px;
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(320px, 0.95fr);
  align-items: center;
  gap: 56px;
}

.hero h1 {
  max-width: 760px;
  margin: 0;
  font-size: clamp(2.35rem, 6vw, 4rem);
  line-height: 1.05;
  letter-spacing: 0;
}

.hero-copy {
  max-width: 620px;
  margin: 22px 0 0;
  color: var(--color-muted);
  font-size: 18px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 30px;
}

.offer-line {
  margin-top: 22px;
  color: #92400e;
  font-size: 14px;
  font-weight: 800;
}

.product-preview {
  overflow: hidden;
  border: 1px solid var(--color-border);
  border-radius: 16px;
  background: var(--color-surface);
  box-shadow: var(--shadow-soft);
}

.preview-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--color-border);
  padding: 14px 16px;
}

.preview-body {
  padding: 20px;
}

.lesson-list {
  display: grid;
  gap: 10px;
}

.lesson-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 12px;
  background: #ffffff;
}

.section {
  padding: 72px 0;
}

.section-heading {
  max-width: 720px;
  margin-bottom: 28px;
}

.section-heading h2 {
  margin: 0;
  font-size: clamp(1.8rem, 3vw, 2.6rem);
  line-height: 1.15;
}

.section-heading p {
  margin: 12px 0 0;
  color: var(--color-muted);
}

.grid {
  display: grid;
  gap: 18px;
}

.grid-3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.card {
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
  padding: 20px;
}

.card h3 {
  margin: 0 0 8px;
  font-size: 18px;
}

.card p {
  margin: 0;
  color: var(--color-muted);
}

.badge {
  display: inline-flex;
  min-height: 28px;
  align-items: center;
  border-radius: 999px;
  padding: 0 10px;
  font-size: 12px;
  font-weight: 800;
}

.badge-free {
  background: #dcfce7;
  color: #166534;
}

.badge-paid {
  background: #dbeafe;
  color: #1e40af;
}

.badge-warning {
  background: #fef3c7;
  color: #92400e;
}

.app-shell {
  display: grid;
  min-height: 100vh;
  grid-template-columns: 260px minmax(0, 1fr);
}

.sidebar {
  border-right: 1px solid var(--color-border);
  background: var(--color-surface);
  padding: 22px;
}

.sidebar-nav {
  display: grid;
  gap: 6px;
  margin-top: 28px;
}

.sidebar-nav a {
  border-radius: var(--radius);
  color: var(--color-muted);
  padding: 10px 12px;
  font-size: 14px;
  font-weight: 700;
}

.sidebar-nav a.active,
.sidebar-nav a:hover {
  background: #eff6ff;
  color: var(--color-primary);
}

.app-main {
  min-width: 0;
  padding: 28px;
}

.app-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 24px;
}

.app-title h1 {
  margin: 0;
  font-size: 28px;
  line-height: 1.2;
}

.app-title p {
  margin: 6px 0 0;
  color: var(--color-muted);
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 16px;
}

.stat-value {
  margin-top: 10px;
  font-size: 28px;
  font-weight: 800;
}

.progress-bar {
  overflow: hidden;
  height: 10px;
  border-radius: 999px;
  background: #e2e8f0;
}

.progress-fill {
  height: 100%;
  border-radius: inherit;
  background: var(--color-primary);
}

.alert {
  border-radius: var(--radius);
  padding: 14px 16px;
  font-weight: 700;
}

.alert-danger {
  border: 1px solid #fecaca;
  background: #fef2f2;
  color: #991b1b;
}

.reader-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 280px;
  gap: 24px;
}

.lesson-content {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
  padding: clamp(22px, 5vw, 42px);
  user-select: none;
}

.lesson-content h1,
.lesson-content h2,
.lesson-content h3 {
  line-height: 1.2;
}

.lesson-content p {
  color: #334155;
}

.lesson-content pre {
  overflow: auto;
  border-radius: var(--radius);
  background: var(--color-code);
  color: #f8fafc;
  padding: 18px;
  font-family: var(--font-mono);
  font-size: 14px;
}

.watermark-layer {
  pointer-events: none;
  position: absolute;
  inset: 0;
  z-index: 1;
  display: grid;
  place-items: center;
  color: rgba(15, 23, 42, 0.08);
  font-size: 20px;
  font-weight: 800;
  line-height: 2.2;
  text-align: center;
  transform: rotate(-24deg);
  white-space: pre-line;
}

.lesson-content > :not(.watermark-layer) {
  position: relative;
  z-index: 2;
}

.reader-aside {
  align-self: start;
  position: sticky;
  top: 92px;
}

.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
}

table {
  width: 100%;
  min-width: 720px;
  border-collapse: collapse;
}

th,
td {
  border-bottom: 1px solid var(--color-border);
  padding: 13px 14px;
  text-align: left;
  font-size: 14px;
}

th {
  color: var(--color-muted);
  font-size: 12px;
  text-transform: uppercase;
}

.footer {
  border-top: 1px solid var(--color-border);
  padding: 34px 0;
  color: var(--color-muted);
}

@media (max-width: 900px) {
  .nav-links,
  .nav-actions {
    display: none;
  }

  .mobile-menu-button {
    display: inline-flex;
  }

  .nav.open {
    flex-wrap: wrap;
    align-items: flex-start;
    padding: 12px 0 16px;
  }

  .nav.open .nav-links,
  .nav.open .nav-actions {
    display: grid;
    position: static;
    flex: 1 0 100%;
    width: 100%;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    background: var(--color-surface);
    padding: 16px;
    box-shadow: var(--shadow-soft);
  }

  .nav.open .nav-actions {
    grid-template-columns: 1fr;
  }

  .hero-grid,
  .reader-shell,
  .app-shell {
    grid-template-columns: 1fr;
  }

  .sidebar {
    border-right: 0;
    border-bottom: 1px solid var(--color-border);
  }

  .sidebar-nav {
    grid-template-columns: repeat(auto-fit, minmax(128px, 1fr));
  }

  .grid-3,
  .stats-grid,
  .section .grid {
    grid-template-columns: 1fr !important;
  }

  .app-main {
    padding: 20px;
  }

  .reader-aside {
    position: static;
  }
}