:root {
  --bg: #0f172a;
  --card: #1e293b;
  --text: #e2e8f0;
  --muted: #94a3b8;
  --accent: #38bdf8;
  --border: #334155;
  --error: #f87171;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
  font: 16px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
}

.card {
  width: 100%;
  max-width: 440px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 2rem;
}

h1 { margin: 0 0 .5rem; font-size: 1.4rem; }

.sub { margin: 0 0 1.5rem; color: var(--muted); font-size: .9rem; }
code { background: rgba(148, 163, 184, .15); padding: .1em .3em; border-radius: 4px; }

form { display: flex; flex-direction: column; gap: .35rem; }
label { font-size: .8rem; color: var(--muted); }

input, select {
  width: 100%;
  padding: .6rem .7rem;
  font-size: 1rem;
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
}
input:focus, select:focus { outline: 2px solid var(--accent); border-color: var(--accent); }

.row { margin-top: .75rem; display: flex; flex-direction: column; gap: .35rem; }

button {
  margin-top: 1.25rem;
  padding: .7rem;
  font-size: 1rem;
  font-weight: 600;
  color: #0f172a;
  background: var(--accent);
  border: 0;
  border-radius: 8px;
  cursor: pointer;
}
button:hover { filter: brightness(1.08); }

#output {
  margin-top: 1.75rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
}

.qr {
  background: #fff;
  padding: 16px; /* quiet-zone margin for reliable scanning */
  border-radius: 12px;
  line-height: 0;
}
.qr canvas, .qr img { display: block; }

.encoded {
  margin: 0;
  max-width: 100%;
  word-break: break-all;
  text-align: center;
  font-size: .85rem;
  color: var(--muted);
}

.downloads { display: flex; gap: .75rem; flex-wrap: wrap; justify-content: center; }

.download {
  font-size: .9rem;
  font-weight: 600;
  color: var(--accent);
  text-decoration: none;
  border: 1px solid var(--border);
  padding: .5rem 1rem;
  border-radius: 8px;
}
.download:hover { border-color: var(--accent); }

.error { margin-top: 1rem; color: var(--error); font-size: .9rem; }