:root {
  color-scheme: light;
  --bg: #f6f8fb;
  --ink: #142033;
  --muted: #607086;
  --line: #d9e1eb;
  --paper: #ffffff;
  --teal: #0f766e;
  --copper: #b75f38;
  --navy: #22324a;
}

* {
  box-sizing: border-box;
}

body {
  background: var(--bg);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  margin: 0;
}

.site-header {
  align-items: center;
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid var(--line);
  display: flex;
  gap: 1rem;
  justify-content: space-between;
  padding: 1rem max(1.25rem, calc((100vw - 1180px) / 2));
  position: sticky;
  top: 0;
  z-index: 10;
}

.brand {
  color: var(--ink);
  font-weight: 800;
  text-decoration: none;
}

nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem;
}

nav a,
.button {
  color: var(--ink);
  font-weight: 700;
  text-decoration: none;
}

main {
  margin: 0 auto;
  max-width: 1180px;
  padding: 2rem 1.25rem 4rem;
}

.hero {
  align-items: center;
  display: grid;
  gap: 2rem;
  grid-template-columns: minmax(0, 1.1fr) minmax(320px, 0.9fr);
  min-height: 560px;
}

.hero h1,
.section h2 {
  font-family: Georgia, "Times New Roman", serif;
  letter-spacing: 0;
}

.hero h1 {
  font-size: clamp(2.55rem, 5vw, 4.5rem);
  line-height: 1;
  margin: 0 0 1rem;
}

.hero p,
.section p,
footer p {
  color: var(--muted);
  line-height: 1.7;
}

.eyebrow {
  color: var(--teal);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  margin: 0 0 0.75rem;
  text-transform: uppercase;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem;
  margin-top: 1.4rem;
}

.button {
  border: 1px solid var(--line);
  border-radius: 8px;
  display: inline-flex;
  padding: 0.78rem 1rem;
}

.button.primary {
  background: var(--teal);
  border-color: var(--teal);
  color: #fff;
}

.button.secondary {
  background: var(--paper);
}

.sheet-preview {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 24px 70px rgba(20, 32, 51, 0.12);
  overflow: hidden;
}

.sheet-toolbar {
  align-items: center;
  background: var(--navy);
  display: flex;
  gap: 0.45rem;
  height: 44px;
  padding: 0 1rem;
}

.sheet-toolbar span {
  background: #ffffff;
  border-radius: 50%;
  height: 0.65rem;
  opacity: 0.7;
  width: 0.65rem;
}

.sheet-grid {
  display: grid;
  grid-template-columns: 48px repeat(3, minmax(86px, 1fr));
}

.sheet-grid div {
  border-bottom: 1px solid var(--line);
  border-right: 1px solid var(--line);
  min-height: 52px;
  padding: 0.85rem;
}

.sheet-grid .head,
.sheet-grid .row-head {
  background: #eef3f8;
  color: var(--muted);
  font-weight: 700;
  text-align: center;
}

.sheet-grid .ok {
  color: var(--teal);
  font-weight: 800;
}

.summary {
  display: grid;
  gap: 1rem;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  margin-bottom: 1rem;
}

.summary div,
.section,
.feature-grid article {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 8px;
}

.summary div {
  padding: 1rem;
}

.summary strong,
.summary span {
  display: block;
}

.summary span {
  color: var(--muted);
  margin-top: 0.35rem;
}

.section {
  margin-top: 1rem;
  padding: 1.4rem;
}

.section h2 {
  font-size: clamp(1.65rem, 3vw, 2.35rem);
  margin: 0 0 1rem;
}

.two-column {
  display: grid;
  gap: 1.2rem;
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

pre {
  background: #132033;
  border-radius: 8px;
  color: #edf4fb;
  overflow: auto;
  padding: 1rem;
}

code {
  font-family: "IBM Plex Mono", "SFMono-Regular", Consolas, monospace;
  font-size: 0.9rem;
}

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

.feature-grid article {
  padding: 1rem;
}

.feature-grid h3 {
  margin: 0 0 0.5rem;
}

table {
  border-collapse: collapse;
  width: 100%;
}

th,
td {
  border-bottom: 1px solid var(--line);
  padding: 0.85rem;
  text-align: left;
  vertical-align: top;
}

th {
  background: #eef3f8;
}

.checklist {
  color: var(--muted);
  display: grid;
  gap: 0.55rem;
  line-height: 1.7;
  margin: 0;
}

footer {
  border-top: 1px solid var(--line);
  margin: 0 auto;
  max-width: 1180px;
  padding: 2rem 1.25rem;
}

@media (max-width: 860px) {
  .site-header,
  .hero,
  .summary,
  .two-column,
  .feature-grid {
    grid-template-columns: 1fr;
  }

  .site-header {
    align-items: flex-start;
    display: grid;
  }

  .hero {
    min-height: auto;
    padding-top: 2rem;
  }

  .sheet-grid {
    grid-template-columns: 38px repeat(3, minmax(72px, 1fr));
  }
}