:root {
  --bg: #ffffff;
  --text: #102030;
  --muted: #4e5d6b;
  --line: #d9e2ea;
  --soft: #f6f9fc;
  --ai: #1f5ea8;
  --human: #2f8f4e;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
}

a {
  color: var(--ai);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.container {
  width: min(1100px, 92%);
  margin: 0 auto;
}

.site-header {
  border-bottom: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.96);
  position: sticky;
  top: 0;
  z-index: 10;
}

.nav-wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 68px;
  gap: 1rem;
}

.brand {
  color: var(--text);
  font-weight: 700;
  letter-spacing: 0.01em;
}

.site-nav {
  display: flex;
  gap: 0.25rem;
  align-items: center;
}

.nav-link {
  color: var(--muted);
  display: inline-flex;
  justify-content: center;
  padding: 0.45rem 0.7rem;
  min-width: 6.4rem;
  border-radius: 8px;
}

.nav-link:hover,
.nav-link.active {
  color: var(--text);
  background: var(--soft);
  text-decoration: none;
}

.nav-toggle {
  display: none;
  border: 1px solid var(--line);
  background: #fff;
  border-radius: 8px;
  padding: 0.45rem 0.65rem;
  color: var(--text);
}

.hero {
  padding: 4.5rem 0 3.5rem;
  border-bottom: 1px solid var(--line);
}

.kicker {
  color: var(--ai);
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 700;
  margin: 0 0 0.8rem;
}

h1, h2, h3 {
  line-height: 1.25;
  margin-top: 0;
}

h1 {
  font-size: clamp(1.8rem, 4vw, 3rem);
  margin-bottom: 1rem;
}

h2 {
  font-size: clamp(1.35rem, 3vw, 2rem);
  margin-bottom: 0.8rem;
}

h3 {
  font-size: 1.05rem;
  margin-bottom: 0.45rem;
}

.lead {
  max-width: 760px;
  color: var(--muted);
  font-size: 1.1rem;
}

.section {
  padding: 3.2rem 0;
}

.section-soft {
  background: var(--soft);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.section-lead {
  color: var(--muted);
  margin-top: 0;
  margin-bottom: 1.3rem;
}

.cards {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}

.card {
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 1rem 1.1rem;
  background: #fff;
}

.two-col {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}

.note {
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fff;
  padding: 1rem 1.1rem;
}

.timeline {
  display: grid;
  gap: 0.8rem;
  margin: 0 0 1.25rem;
}

.timeline article {
  border-left: 3px solid var(--ai);
  padding-left: 0.8rem;
}

.btn {
  display: inline-block;
  border-radius: 10px;
  padding: 0.55rem 0.9rem;
  border: 1px solid transparent;
  font-weight: 600;
  text-decoration: none;
}

.btn:hover {
  text-decoration: none;
}

.btn-ai {
  background: var(--ai);
  color: #fff;
}

.btn-ai:hover {
  background: #174f8e;
}

.btn-line {
  color: var(--text);
  border-color: var(--line);
  background: #fff;
}

.cta-row {
  display: flex;
  gap: 0.6rem;
  flex-wrap: wrap;
}

.prose {
  max-width: 820px;
}

.prose ul {
  margin: 0.4rem 0 1.2rem 1rem;
}

.prose li {
  margin-bottom: 0.35rem;
}

.notice {
  border-left: 3px solid var(--human);
  background: #f4fbf6;
  padding: 0.65rem 0.75rem;
  border-radius: 8px;
}

.diagram {
  margin-top: 1.6rem;
}

.flow {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.5rem;
  align-items: center;
}

.flow-box {
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 0.7rem;
  text-align: center;
  background: #fff;
}

.flow-arrow {
  text-align: center;
  color: var(--muted);
}

.form-ui {
  display: grid;
  gap: 0.55rem;
}

label {
  font-weight: 600;
  font-size: 0.92rem;
}

input,
textarea {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 0.6rem 0.7rem;
  font: inherit;
}

input:focus,
textarea:focus {
  outline: 2px solid #cfe2f6;
  border-color: var(--ai);
}

.site-footer {
  border-top: 1px solid var(--line);
  margin-top: 2.5rem;
}

.footer-wrap {
  min-height: 72px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 0.2rem;
  color: var(--muted);
  font-size: 0.92rem;
}

.ai {
  color: var(--ai);
}

.human {
  color: var(--human);
}

@media (min-width: 760px) {
  .cards {
    grid-template-columns: repeat(2, 1fr);
  }

  .two-col {
    grid-template-columns: 1.15fr 1fr;
  }

  .footer-wrap {
    flex-direction: row;
    justify-content: space-between;
    align-items: center;
  }

  .flow {
    grid-template-columns: 1fr auto 1fr auto 1fr auto 1fr;
  }
}

@media (max-width: 759px) {
  .nav-toggle {
    display: inline-block;
  }

  .site-nav {
    position: absolute;
    top: 68px;
    left: 0;
    right: 0;
    background: #fff;
    border-bottom: 1px solid var(--line);
    flex-direction: column;
    align-items: stretch;
    padding: 0.4rem;
    display: none;
  }

  .site-nav.open {
    display: flex;
  }
}