/* Tianfu Agent — layout inspired by structured long-form landing pages */
:root {
  --bg: #faf9f7;
  --surface: #ffffff;
  --ink: #1a1f26;
  --muted: #5c6470;
  --line: #e6e4df;
  --accent: #b8922e;
  --accent-ink: #6b5210;
  --max: 720px;
  --wide: 920px;
  --font: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, monospace;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font);
  font-size: 17px;
  line-height: 1.55;
  color: var(--ink);
  background: var(--bg);
}

a {
  color: var(--accent-ink);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

a:hover {
  color: var(--ink);
}

.wrap {
  max-width: var(--wide);
  margin: 0 auto;
  padding: 0 24px;
}

.narrow {
  max-width: var(--max);
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(250, 249, 247, 0.92);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(8px);
}

.site-header .inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  min-height: 52px;
  padding-block: 6px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  color: var(--ink);
  text-decoration: none;
  font-weight: 600;
  letter-spacing: -0.02em;
}

.brand img {
  width: 28px;
  height: 28px;
  display: block;
}

.nav-inline {
  display: flex;
  gap: 18px;
  flex-wrap: wrap;
  font-size: 13px;
}

.nav-inline a {
  color: var(--muted);
  text-decoration: none;
}

.nav-inline a:hover {
  color: var(--ink);
}

/* Hero */
.hero {
  padding: 56px 0 40px;
  border-bottom: 1px solid var(--line);
}

.hero-kicker {
  font-family: var(--mono);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--muted);
  margin: 0 0 12px;
}

.hero h1 {
  font-size: clamp(1.85rem, 4vw, 2.35rem);
  line-height: 1.15;
  letter-spacing: -0.03em;
  margin: 0 0 16px;
  font-weight: 650;
}

.hero-lead {
  font-size: 1.05rem;
  color: var(--muted);
  margin: 0 0 28px;
  max-width: 52ch;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 20px;
  font-family: var(--font);
  font-size: 15px;
  font-weight: 600;
  color: var(--surface);
  background: var(--ink);
  border: 1px solid var(--ink);
  border-radius: 6px;
  text-decoration: none;
  cursor: pointer;
}

.btn-primary:hover {
  background: #0b0e12;
  border-color: #0b0e12;
  color: var(--surface);
}

.btn-ghost {
  display: inline-flex;
  align-items: center;
  padding: 12px 16px;
  font-size: 15px;
  font-weight: 500;
  color: var(--muted);
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--surface);
  text-decoration: none;
}

.btn-ghost:hover {
  color: var(--ink);
  border-color: #d6d3cc;
}

/* Meta strip */
.meta-strip {
  padding: 28px 0;
  border-bottom: 1px solid var(--line);
}

.meta-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 20px;
}

@media (max-width: 800px) {
  .meta-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.meta-item dt {
  font-family: var(--mono);
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
  margin: 0 0 6px;
}

.meta-item dd {
  margin: 0;
  font-size: 15px;
  font-weight: 600;
}

/* Sections */
section {
  padding: 48px 0;
  border-bottom: 1px solid var(--line);
}

section:last-of-type {
  border-bottom: none;
}

.section-label {
  font-family: var(--mono);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--muted);
  margin: 0 0 10px;
}

section h2 {
  font-size: 1.45rem;
  letter-spacing: -0.02em;
  margin: 0 0 16px;
  font-weight: 650;
}

section h3 {
  font-size: 1.05rem;
  margin: 24px 0 8px;
  font-weight: 600;
}

.lead-block {
  color: var(--muted);
  margin: 0 0 28px;
  max-width: 62ch;
}

.card-grid {
  display: grid;
  gap: 20px;
}

@media (min-width: 640px) {
  .card-grid.two {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 20px 20px 18px;
}

.card h3 {
  margin-top: 0;
  font-size: 1rem;
}

.card p {
  margin: 0;
  color: var(--muted);
  font-size: 15px;
}

/* Steps */
.steps {
  counter-reset: step;
  display: grid;
  gap: 20px;
}

.step {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 16px;
  align-items: start;
  padding: 18px 0;
  border-top: 1px solid var(--line);
}

.step:first-child {
  border-top: none;
  padding-top: 0;
}

.step-num {
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 600;
  color: var(--accent-ink);
  min-width: 2.25rem;
}

.steps .step-num::before {
  counter-increment: step;
  content: counter(step, decimal-leading-zero);
}

.step-body h3 {
  margin: 0 0 6px;
  font-size: 1rem;
}

.step-body p {
  margin: 0;
  color: var(--muted);
  font-size: 15px;
}

/* FAQ */
.faq-item {
  padding: 18px 0;
  border-top: 1px solid var(--line);
}

.faq-item:first-child {
  border-top: none;
  padding-top: 0;
}

.faq-item h3 {
  margin: 0 0 8px;
  font-size: 1rem;
}

.faq-item p {
  margin: 0;
  color: var(--muted);
  font-size: 15px;
}

/* Sources */
.sources {
  display: grid;
  gap: 12px;
}

.source-link {
  display: block;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  text-decoration: none;
  color: var(--ink);
}

.source-link strong {
  display: block;
  font-size: 15px;
  margin-bottom: 4px;
}

.source-link span {
  font-size: 14px;
  color: var(--muted);
}

.source-link:hover {
  border-color: #d0cdc4;
}

/* Footer */
.site-footer {
  padding: 32px 0 48px;
  font-size: 14px;
  color: var(--muted);
}

.site-footer p {
  margin: 0 0 8px;
}