:root {
  --brand: #0a3d62;
  --brand-2: #1e6091;
  --accent: #00b894;
  --bg: #eef2f6;
  --card: #ffffff;
  --text: #1d2733;
  --muted: #6b7785;
  --border: #d9e0e7;
  --error: #d63031;
  --radius: 16px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  background: linear-gradient(135deg, #eef2f6 0%, #dce6f0 100%);
  font-family: "Segoe UI", "Sarabun", "Noto Sans Thai", system-ui, sans-serif;
  color: var(--text);
}

.card {
  width: 100%;
  max-width: 460px;
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: 0 12px 40px rgba(10, 61, 98, 0.12);
  padding: 28px;
}

header h1 {
  margin: 0 0 4px;
  font-size: 1.5rem;
  color: var(--brand);
}
.sub { margin: 0 0 20px; color: var(--muted); font-size: 0.9rem; }

.seg {
  display: flex;
  gap: 6px;
  background: var(--bg);
  border-radius: 10px;
  padding: 4px;
  margin-bottom: 18px;
}
.seg-btn {
  flex: 1;
  border: 0;
  background: transparent;
  padding: 10px 8px;
  border-radius: 8px;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--muted);
  cursor: pointer;
  transition: all 0.15s;
}
.seg-btn.active {
  background: var(--card);
  color: var(--brand);
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.08);
}

.field { display: block; margin-bottom: 16px; }
.field span { display: block; font-size: 0.82rem; color: var(--muted); margin-bottom: 6px; }
.field input {
  width: 100%;
  padding: 12px 14px;
  font-size: 1rem;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  outline: none;
  transition: border-color 0.15s;
}
.field input:focus { border-color: var(--brand-2); }

button.primary {
  width: 100%;
  border: 0;
  padding: 13px;
  font-size: 1rem;
  font-weight: 700;
  color: #fff;
  background: var(--brand);
  border-radius: 10px;
  cursor: pointer;
  transition: background 0.15s;
}
button.primary:hover { background: var(--brand-2); }

button.ghost {
  width: 100%;
  border: 1.5px solid var(--border);
  background: transparent;
  padding: 12px;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--brand);
  border-radius: 10px;
  cursor: pointer;
}

.error { color: var(--error); font-size: 0.85rem; margin: 10px 0 0; min-height: 1em; }

.result { margin-top: 24px; text-align: center; }
.hidden { display: none; }

.qr-frame {
  display: inline-block;
  padding: 18px 18px 14px;
  background: #fff;
  border: 2px solid var(--brand);
  border-radius: 14px;
}
.qr-brand {
  font-weight: 800;
  color: var(--brand);
  letter-spacing: 0.5px;
  margin-bottom: 12px;
  font-size: 1.1rem;
}
#qr { display: block; margin: 0 auto; }
.amount-display {
  margin-top: 10px;
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--accent);
}

.actions { display: flex; flex-direction: column; gap: 10px; margin-top: 18px; }

.payload { margin-top: 16px; text-align: left; }
.payload summary { cursor: pointer; color: var(--muted); font-size: 0.85rem; }
.payload code {
  display: block;
  margin-top: 8px;
  padding: 10px;
  background: var(--bg);
  border-radius: 8px;
  font-size: 0.72rem;
  word-break: break-all;
  color: var(--text);
}

footer p { margin: 20px 0 0; text-align: center; font-size: 0.75rem; color: var(--muted); }