:root {
  --bg: #f5f7fb;
  --panel: #ffffff;
  --ink: #0f172a;
  --muted: #5b6475;
  --line: #e3e8f0;
  --accent: #2775ca; /* USDC blue */
  --accent-ink: #ffffff;
  --ok: #0f9f6e;
  --ok-bg: #e7f7f0;
  --warn: #b45309;
  --warn-bg: #fff4e5;
  --err: #c0262d;
  --err-bg: #fdecec;
  --radius: 14px;
  --shadow: 0 1px 2px rgba(15, 23, 42, 0.06), 0 8px 24px rgba(15, 23, 42, 0.06);
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  color: var(--ink);
  background: var(--bg);
}

* { box-sizing: border-box; }
body { margin: 0; min-height: 100vh; display: flex; flex-direction: column; }
a { color: var(--accent); }
[hidden] { display: none !important; }

header.top {
  display: flex; align-items: center; gap: 16px; flex-wrap: wrap;
  padding: 14px 24px; background: var(--panel); border-bottom: 1px solid var(--line);
}
.brand { font-weight: 800; font-size: 20px; letter-spacing: -0.02em; text-decoration: none; color: var(--ink); }
.brand span { color: var(--accent); }
nav { display: flex; gap: 6px; }
nav a {
  text-decoration: none; color: var(--muted); padding: 6px 12px; border-radius: 999px; font-weight: 600; font-size: 14px;
}
nav a.active { background: #e8f1fb; color: var(--accent); }
.spacer { flex: 1; }
.badge {
  font-size: 12px; font-weight: 700; padding: 4px 10px; border-radius: 999px; background: #eef2f7; color: var(--muted);
}
.badge.live { background: var(--ok-bg); color: var(--ok); }

main { width: 100%; max-width: 880px; margin: 28px auto; padding: 0 16px; flex: 1; }
.card {
  background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius);
  box-shadow: var(--shadow); padding: 24px; margin-bottom: 18px;
}
h1 { font-size: 26px; letter-spacing: -0.02em; margin: 0 0 6px; }
h2 { font-size: 18px; margin: 0 0 14px; }
p.lead { color: var(--muted); margin: 0 0 18px; }

label { display: block; font-weight: 600; font-size: 14px; margin: 14px 0 6px; }
.hint { color: var(--muted); font-size: 12px; font-weight: 400; }
input, select, textarea {
  width: 100%; font: inherit; font-size: 15px; padding: 10px 12px; border-radius: 10px;
  border: 1px solid var(--line); background: #fbfcfe; color: var(--ink);
}
input:focus, select:focus, textarea:focus { outline: 2px solid #bcd6f3; border-color: var(--accent); }
.row { display: flex; gap: 10px; align-items: center; }
.row > * { flex: 1; }
.row > .shrink { flex: 0 0 auto; }

button {
  font: inherit; font-weight: 700; font-size: 15px; border: 0; border-radius: 10px; padding: 11px 18px;
  background: var(--accent); color: var(--accent-ink); cursor: pointer;
}
button.secondary { background: #e8f1fb; color: var(--accent); }
button.ghost { background: transparent; color: var(--accent); border: 1px solid var(--line); }
button:disabled { opacity: 0.5; cursor: not-allowed; }
button.big { width: 100%; padding: 15px; font-size: 17px; margin-top: 18px; }

.amount { font-size: 40px; font-weight: 800; letter-spacing: -0.03em; }
.amount small { font-size: 18px; color: var(--muted); font-weight: 700; }
.kv { display: grid; grid-template-columns: 130px 1fr; gap: 8px 12px; margin-top: 14px; font-size: 14px; }
.kv dt { color: var(--muted); }
.kv dd { margin: 0; word-break: break-all; }
.mono { font-family: var(--mono); font-size: 13px; }

.pill { display: inline-block; font-size: 13px; font-weight: 800; padding: 5px 12px; border-radius: 999px; }
.pill.unpaid { background: #eef2f7; color: var(--muted); }
.pill.paid { background: var(--ok-bg); color: var(--ok); }
.pill.expired { background: var(--warn-bg); color: var(--warn); }

.result { display: grid; grid-template-columns: 200px 1fr; gap: 20px; align-items: start; }
.qr { width: 200px; height: 200px; border: 1px solid var(--line); border-radius: 12px; padding: 6px; background: #fff; image-rendering: pixelated; }
@media (max-width: 640px) { .result { grid-template-columns: 1fr; } .qr { margin: 0 auto; } .kv { grid-template-columns: 1fr; } }

.status { margin-top: 14px; padding: 12px 14px; border-radius: 10px; font-size: 14px; background: #eef2f7; color: var(--muted); }
.status.ok { background: var(--ok-bg); color: var(--ok); font-weight: 700; }
.status.err { background: var(--err-bg); color: var(--err); }
.status.warn { background: var(--warn-bg); color: var(--warn); }

table { width: 100%; border-collapse: collapse; font-size: 14px; }
th, td { text-align: left; padding: 10px 8px; border-bottom: 1px solid var(--line); vertical-align: top; }
th { color: var(--muted); font-weight: 600; font-size: 12px; text-transform: uppercase; letter-spacing: 0.04em; }
.stats { display: flex; gap: 12px; margin: 14px 0; flex-wrap: wrap; }
.stat { flex: 1; min-width: 150px; background: #f7f9fc; border: 1px solid var(--line); border-radius: 12px; padding: 12px 14px; }
.stat b { display: block; font-size: 22px; }
.stat span { color: var(--muted); font-size: 12px; }

footer { text-align: center; color: var(--muted); font-size: 12px; padding: 18px 16px 28px; }
footer a { color: var(--muted); }