:root {
  --bg: #0f172a;
  --panel: #1e293b;
  --panel-2: #111827;
  --text: #e2e8f0;
  --muted: #94a3b8;
  --accent: #38bdf8;
  --accent-2: #818cf8;
  --border: #334155;
  --radius: 14px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Noto Sans Thai", sans-serif;
  background: radial-gradient(1200px 600px at 10% -10%, #1e3a8a33, transparent),
              radial-gradient(800px 400px at 100% 0%, #7c3aed22, transparent),
              var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.55;
}

header {
  text-align: center;
  padding: 48px 20px 16px;
}
header h1 {
  margin: 0;
  font-size: clamp(28px, 4vw, 40px);
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.sub { color: var(--muted); margin: 6px 0 0; }

main {
  max-width: 1100px;
  margin: 24px auto;
  padding: 0 20px 48px;
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: 20px;
}
main > .docs { grid-column: 1 / -1; }

@media (max-width: 880px) {
  main { grid-template-columns: 1fr; }
}

.card {
  background: linear-gradient(180deg, var(--panel), var(--panel-2));
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.25);
}

label {
  display: block;
  font-size: 13px;
  color: var(--muted);
  margin: 8px 0 6px;
}

textarea, input, select {
  width: 100%;
  background: #0b1220;
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 10px;
  padding: 10px 12px;
  font-size: 14px;
  font-family: inherit;
  outline: none;
  transition: border-color .15s, box-shadow .15s;
}
textarea { resize: vertical; min-height: 70px; }
textarea:focus, input:focus, select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px #38bdf833;
}
input[type="color"] { padding: 4px; height: 42px; cursor: pointer; }

.grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-top: 6px;
}
@media (max-width: 600px) { .grid { grid-template-columns: repeat(2, 1fr); } }

.actions {
  display: flex;
  gap: 10px;
  margin-top: 16px;
  flex-wrap: wrap;
}

button {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #0b1220;
  border: 0;
  border-radius: 10px;
  padding: 10px 16px;
  font-weight: 600;
  font-size: 14px;
  cursor: pointer;
  transition: transform .08s, filter .15s;
}
button:hover { filter: brightness(1.08); }
button:active { transform: translateY(1px); }
button.ghost {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
}

.preview {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 14px;
}
.qr-box {
  width: 100%;
  max-width: 360px;
  aspect-ratio: 1;
  background: #fff;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 12px;
  overflow: hidden;
}
.qr-box img, .qr-box svg, .qr-box canvas { max-width: 100%; max-height: 100%; }
.qr-box .hint { color: #94a3b8; font-size: 13px; }
.api-url {
  width: 100%;
  word-break: break-all;
  background: #0b1220;
  border: 1px solid var(--border);
  padding: 10px 12px;
  border-radius: 10px;
  font-size: 12px;
  color: var(--muted);
}

.docs h2 { margin-top: 0; }
.docs h3 { margin-top: 18px; color: var(--accent); }
pre {
  background: #0b1220;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px;
  overflow-x: auto;
  font-size: 13px;
}
code { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; }
table { width: 100%; border-collapse: collapse; font-size: 14px; }
th, td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border); }
th { color: var(--muted); font-weight: 600; }

footer {
  text-align: center;
  color: var(--muted);
  padding: 20px;
  font-size: 13px;
}