:root {
  --ink: #0f172a;
  --muted: #64748b;
  --line: #e2e8f0;
  --bg: #ffffff;
  --bg-soft: #f8fafc;
  --accent: #1a7f5a;
  --accent-ink: #0b5138;
  --nav-bg: rgba(255, 255, 255, .85);
  --code-bg: #f1f5f9;
  --warn-bg: #fef3c7;
  --warn-ink: #92400e;
  --warn-border: #fcd34d;
  --badge-bg: #e0f2fe;
  --badge-ink: #075985;
  --max: 880px;
}

/* Dark: follow the system unless the user has explicitly chosen light. */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --ink: #e7ecf3; --muted: #94a3b8; --line: #1f2a3d;
    --bg: #0b1020; --bg-soft: #131b2e;
    --accent: #34d399; --accent-ink: #6ee7b7;
    --nav-bg: rgba(11, 16, 32, .8);
    --code-bg: #1e293b;
    --warn-bg: #3b2f12; --warn-ink: #fcd34d; --warn-border: #6b4f1a;
    --badge-bg: #0c4a6e; --badge-ink: #bae6fd;
  }
}
/* Dark: forced on via the toggle, regardless of system. */
:root[data-theme="dark"] {
  --ink: #e7ecf3; --muted: #94a3b8; --line: #1f2a3d;
  --bg: #0b1020; --bg-soft: #131b2e;
  --accent: #34d399; --accent-ink: #6ee7b7;
  --nav-bg: rgba(11, 16, 32, .8);
  --code-bg: #1e293b;
  --warn-bg: #3b2f12; --warn-ink: #fcd34d; --warn-border: #6b4f1a;
  --badge-bg: #0c4a6e; --badge-ink: #bae6fd;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font: 16px/1.65 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  color: var(--ink);
  background: var(--bg);
  transition: background .2s ease, color .2s ease;
}
a { color: var(--accent-ink); }

header.nav {
  position: sticky; top: 0; z-index: 10;
  display: flex; align-items: center; gap: .6rem;
  padding: .6rem 1.25rem;
  background: var(--nav-bg); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
header.nav .brand { display: flex; align-items: center; gap: .5rem; font-weight: 700; color: var(--ink); text-decoration: none; }
header.nav .brand img { width: 28px; height: 28px; border-radius: 7px; }
header.nav nav { margin-left: auto; display: flex; align-items: center; gap: 1.1rem; font-size: 14px; }
header.nav nav a { color: var(--muted); text-decoration: none; }
header.nav nav a:hover { color: var(--ink); }
#theme-toggle {
  font: inherit; font-size: 13px; cursor: pointer;
  padding: .35rem .7rem; border-radius: 999px;
  border: 1px solid var(--line); background: var(--bg-soft); color: var(--ink);
}

section { max-width: var(--max); margin: 0 auto; padding: 4rem 1.25rem; }
section + section { border-top: 1px solid var(--line); }
.hero { padding-top: 5rem; padding-bottom: 3rem; }
.hero h1 { font-size: clamp(2rem, 5vw, 3rem); line-height: 1.1; margin: 0 0 1rem; }
.hero .tag { font-size: 1.25rem; color: var(--muted); margin: 0 0 2rem; max-width: 40ch; }
.hero .cta { display: flex; gap: .75rem; flex-wrap: wrap; }

h2 { font-size: 1.6rem; margin: 0 0 1.25rem; }
h3 { font-size: 1.05rem; margin: 1.5rem 0 .5rem; }
.lede { color: var(--muted); max-width: 60ch; }

.btn {
  display: inline-block; padding: .65rem 1.2rem; border-radius: 8px;
  font-weight: 600; text-decoration: none; border: 1px solid var(--line);
  color: var(--ink); background: var(--bg);
}
.btn.primary { background: var(--accent); color: #fff; border-color: var(--accent); }

.why { display: grid; grid-template-columns: 1fr 1fr; gap: 1.25rem; margin-top: 1rem; }
.why .item { padding: 1.1rem 1.25rem; background: var(--bg-soft); border: 1px solid var(--line); border-radius: 10px; }
.why .item h3 { margin-top: 0; }
.why .item p { margin: 0; color: var(--muted); font-size: 15px; }

.callout {
  margin-top: 1.75rem; padding: 1.1rem 1.25rem;
  background: var(--warn-bg); color: var(--warn-ink);
  border: 1px solid var(--warn-border); border-radius: 10px; font-size: 15px;
}

.demo-wrap { display: flex; flex-wrap: wrap; gap: 1.5rem; align-items: flex-start; margin-top: 1rem; }
.demo-stage { flex: 0 0 auto; padding: 1.5rem; background: var(--bg-soft); border: 1px solid var(--line); border-radius: 12px; }
.demo-controls { font-size: 14px; color: var(--muted); margin-top: 1rem; }
.demo-controls strong { color: var(--ink); display: block; margin-bottom: .25rem; font-size: 13px; }
.demo-controls label { display: inline-block; margin: .15rem .6rem .15rem 0; }
.demo-out { flex: 1 1 280px; min-width: 260px; }
.demo-out .badge { display: inline-block; font-size: 12px; font-weight: 600; padding: 2px 8px; border-radius: 999px; background: var(--badge-bg); color: var(--badge-ink); margin-bottom: .5rem; }
.demo-out pre { margin: 0; }

table { width: 100%; border-collapse: collapse; font-size: 14px; margin: .5rem 0 1rem; }
th, td { text-align: left; padding: .5rem .6rem; border-bottom: 1px solid var(--line); vertical-align: top; }
th { color: var(--muted); font-weight: 600; }
td code { white-space: nowrap; }

code { background: var(--code-bg); padding: 1px 6px; border-radius: 5px; font-size: .9em; }
pre { background: #0b1020; color: #e2e8f0; padding: 1rem 1.1rem; border-radius: 10px; overflow-x: auto; font-size: 13.5px; line-height: 1.6; border: 1px solid var(--line); }
pre code { background: none; padding: 0; color: inherit; font-size: inherit; }

/* examples gallery + sandbox harness */
.gallery { display: grid; grid-template-columns: 1fr 1fr; gap: 1.25rem; margin-top: 1.5rem; }
.ex { padding: 1.25rem; background: var(--bg-soft); border: 1px solid var(--line); border-radius: 12px; }
.ex h3 { margin: 0 0 .9rem; }
.ex pre { font-size: 12.5px; margin: .9rem 0 0; }
.ex .res { font-size: 12.5px; color: var(--muted); margin-top: .6rem; min-height: 1.2em; font-family: ui-monospace, monospace; }
peer-pay.brand { --peerpay-accent: #6d28d9; --peerpay-radius: 14px; }

/* playground: visual editor */
.pg { display: grid; grid-template-columns: 300px 1fr; gap: 2rem; margin-top: 1.5rem; }
.pg-controls { display: flex; flex-direction: column; gap: .9rem; }
.pg-field { display: flex; flex-direction: column; gap: .25rem; font-size: 13px; color: var(--muted); }
.pg-field label { font-weight: 600; color: var(--ink); }
.pg-field input[type=text], .pg-field input[type=number], .pg-field select {
  font: inherit; font-size: 14px; padding: .45rem .6rem; border: 1px solid var(--line);
  border-radius: 8px; background: var(--bg); color: var(--ink);
}
.pg-field input[type=color] { width: 100%; height: 36px; padding: 2px; border: 1px solid var(--line); border-radius: 8px; background: var(--bg); }
.pg-field input[type=range] { width: 100%; }
.pg-chains { display: flex; flex-wrap: wrap; gap: .5rem 1rem; }
.pg-chains label { font-weight: 400; color: var(--ink); display: inline-flex; gap: .3rem; align-items: center; }
.pg-right { display: flex; flex-direction: column; gap: 1.25rem; }
.pg-stage { padding: 1.75rem; background: var(--bg-soft); border: 1px solid var(--line); border-radius: 12px; display: flex; align-items: center; justify-content: center; min-height: 90px; }
.pg-out h3 { display: flex; align-items: center; gap: .6rem; }
.copy-btn {
  font: inherit; font-size: 12px; font-weight: 600; cursor: pointer;
  padding: .25rem .6rem; border-radius: 6px; border: 1px solid var(--line);
  background: var(--bg-soft); color: var(--ink);
}
.copy-btn.ok { background: var(--badge-bg); color: var(--badge-ink); border-color: transparent; }
.pg-out textarea { width: 100%; min-height: 120px; font: 12.5px ui-monospace, monospace; padding: 1rem; border-radius: 10px; border: 1px solid var(--line); background: #0b1020; color: #e2e8f0; resize: vertical; }
@media (max-width: 720px) { .pg { grid-template-columns: 1fr; } }
header.nav nav a.active { color: var(--accent-ink); font-weight: 600; }
.toggles { margin: 1rem 0 .5rem; font-size: 14px; color: var(--muted); }
.toggles label { display: block; margin: .25rem 0; }
.check { padding: .5rem .75rem; border-radius: 8px; margin: .4rem 0; font-size: 13px; font-family: ui-monospace, monospace; }
.check.pass { background: var(--badge-bg); color: var(--badge-ink); }
.check.fail { background: var(--warn-bg); color: var(--warn-ink); }

footer { max-width: var(--max); margin: 0 auto; padding: 3rem 1.25rem 5rem; color: var(--muted); font-size: 14px; border-top: 1px solid var(--line); }
footer a { color: var(--muted); }

@media (max-width: 640px) {
  .why { grid-template-columns: 1fr; }
  header.nav nav { gap: .75rem; }
}