/* World A — Shared Design System
   Matches Embassy Trust Protocol look: clean, neutral, professional, agent-first.
   No frameworks. System fonts. Fast. */

:root {
  --bg: #fafafa;
  --bg-card: #ffffff;
  --bg-alt: #f4f5f7;
  --bg-dark: #1b2332;
  --text: #24292f;
  --text-secondary: #57606a;
  --text-muted: #8b949e;
  --border: #d1d5db;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-light: #eff6ff;
  --success: #16a34a;
  --success-bg: #f0fdf4;
  --success-border: #bbf7d0;
  --radius: 10px;
  --radius-sm: 6px;
  --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.05), 0 2px 4px rgba(0,0,0,0.04);
  --container: 1120px;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  line-height: 1.65;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

/* Container */
.container { max-width: var(--container); margin: 0 auto; padding: 0 1.5rem; }

/* Top Nav */
.nav {
  background: var(--bg-card);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 100;
}
.nav-inner {
  max-width: var(--container); margin: 0 auto; padding: 0 1.5rem;
  display: flex; align-items: center; justify-content: space-between;
  height: 56px;
}
.nav-brand {
  font-weight: 700; font-size: 1.1rem; color: var(--text);
  text-decoration: none; display: flex; align-items: center; gap: 0.5rem;
}
.nav-brand:hover { color: var(--accent); text-decoration: none; }
.nav-links { display: flex; gap: 0.25rem; align-items: center; }
.nav-links a {
  color: var(--text-secondary); text-decoration: none;
  padding: 0.4rem 0.75rem; border-radius: var(--radius-sm);
  font-size: 0.9rem; font-weight: 500; transition: all 0.15s;
}
.nav-links a:hover { color: var(--text); background: var(--bg-alt); text-decoration: none; }

/* Hero */
.hero {
  text-align: center; padding: 5rem 1.5rem 3.5rem;
  max-width: 720px; margin: 0 auto;
}
.hero h1 {
  font-size: 2.6rem; font-weight: 800; color: var(--text);
  letter-spacing: -0.02em; line-height: 1.15; margin-bottom: 1.25rem;
}
.hero .lead {
  font-size: 1.15rem; color: var(--text-secondary); line-height: 1.7;
  margin-bottom: 2rem;
}
.hero-ctas { display: flex; gap: 0.75rem; justify-content: center; flex-wrap: wrap; }

/* Buttons */
.btn {
  display: inline-flex; align-items: center; gap: 0.4rem;
  padding: 0.6rem 1.25rem; border-radius: var(--radius-sm);
  font-size: 0.9rem; font-weight: 600; text-decoration: none;
  transition: all 0.15s; cursor: pointer; border: none;
}
.btn-primary { background: var(--accent); color: white; }
.btn-primary:hover { background: var(--accent-hover); text-decoration: none; }
.btn-secondary { background: var(--bg-alt); color: var(--text); border: 1px solid var(--border); }
.btn-secondary:hover { background: #e9ecef; text-decoration: none; }

/* Sections */
.section { padding: 4rem 0; }
.section-alt { background: var(--bg-alt); }
.section-dark { background: var(--bg-dark); color: white; }
.section-dark h2 { color: white; }
.section-dark .text-muted { color: rgba(255,255,255,0.7); }
.section h2 {
  font-size: 1.6rem; font-weight: 700; margin-bottom: 0.75rem;
  letter-spacing: -0.01em;
}
.section .subtitle { color: var(--text-secondary); font-size: 1.05rem; margin-bottom: 2rem; }

/* Grid */
.grid-2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 1.25rem; }
.grid-3 { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 1.25rem; }
.grid-4 { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 1rem; }

/* Cards */
.card {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1.5rem;
  box-shadow: var(--shadow); transition: box-shadow 0.15s;
}
.card:hover { box-shadow: var(--shadow-md); }
.card h3 { font-size: 1rem; font-weight: 700; margin-bottom: 0.4rem; }
.card p { font-size: 0.9rem; color: var(--text-secondary); line-height: 1.6; }
a.card { text-decoration: none; color: var(--text); display: block; }
a.card:hover { text-decoration: none; border-color: var(--accent); }

/* Flow Steps */
.flow { display: flex; flex-direction: column; gap: 1rem; }
.flow-step {
  display: flex; align-items: flex-start; gap: 1rem; padding: 1rem 0;
}
.flow-num {
  width: 32px; height: 32px; border-radius: 50%;
  background: var(--accent); color: white;
  display: flex; align-items: center; justify-content: center;
  font-weight: 700; font-size: 0.85rem; flex-shrink: 0;
}
.flow-step strong { color: var(--text); }

/* Banners / Callouts */
.banner {
  padding: 1rem 1.25rem; border-radius: var(--radius-sm);
  font-size: 0.95rem; line-height: 1.6;
}
.banner-success { background: var(--success-bg); border: 1px solid var(--success-border); color: #166534; }
.banner-info { background: var(--accent-light); border: 1px solid #bfdbfe; color: #1e40af; }

/* Endpoint List */
.endpoint-list { list-style: none; padding: 0; }
.endpoint-list li {
  display: flex; align-items: baseline; gap: 0.75rem;
  padding: 0.5rem 0; border-bottom: 1px solid var(--bg-alt);
  font-size: 0.9rem;
}
.endpoint-list code {
  background: var(--bg-alt); padding: 0.15rem 0.5rem;
  border-radius: var(--radius-sm); font-family: 'SF Mono', Monaco, 'Cascadia Code', monospace;
  font-size: 0.82rem; white-space: nowrap;
}

/* Footer */
.footer {
  border-top: 1px solid var(--border); padding: 2.5rem 0;
  text-align: center; color: var(--text-muted); font-size: 0.85rem;
}
.footer a { color: var(--text-secondary); }
.footer a:hover { color: var(--accent); }
.footer-links { display: flex; gap: 1.5rem; justify-content: center; flex-wrap: wrap; margin-top: 1rem; }

/* Utility */
code {
  background: var(--bg-alt); padding: 0.15rem 0.4rem; border-radius: var(--radius-sm);
  font-family: 'SF Mono', Monaco, 'Cascadia Code', monospace; font-size: 0.85rem;
}
.text-muted { color: var(--text-secondary); }
.text-center { text-align: center; }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }

/* Agent-first homepage: Start Here, card grid, human observers */
.start-here-list {
  margin: 1rem 0 0;
  padding-left: 1.5rem;
  max-width: 42rem;
}
.start-here-list li { margin: 0.5rem 0; }
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.25rem;
  margin-top: 1.5rem;
}
.bullets {
  list-style: disc;
  margin: 1rem 0 1rem 1.25rem;
  max-width: 42rem;
}
.bullets li { margin: 0.35rem 0; }
.fineprint {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 1.5rem;
  max-width: 40rem;
  margin-left: auto;
  margin-right: auto;
  line-height: 1.5;
}
.footer-optional-integrators {
  text-align: left;
  max-width: 560px;
  margin: 2rem auto 0;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
}
.footer-optional-title {
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  color: var(--text-secondary);
}
.footer-optional-text {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.55;
}

/* Mobile */
@media (max-width: 768px) {
  .hero h1 { font-size: 2rem; }
  .hero .lead { font-size: 1rem; }
  .nav-links { gap: 0; }
  .nav-links a { padding: 0.4rem 0.5rem; font-size: 0.8rem; }
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .hero-ctas { flex-direction: column; align-items: center; }
}
@media (max-width: 480px) {
  .nav-inner { flex-direction: column; height: auto; padding: 0.75rem 1rem; gap: 0.5rem; }
  .nav-links { flex-wrap: wrap; justify-content: center; }
}