:root {
  --bg: #0f1220;
  --card: #171a2b;
  --text: #e9ecff;
  --muted: #aab0d6;
  --line: #2a2f4a;
  --accent: #7c5cff;
  --danger: #ff5c7a;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  background: radial-gradient(1200px 600px at 20% 10%, #1b2150 0%, var(--bg) 60%);
  color: var(--text);
  display: grid;
  place-items: center;
  padding: 24px;
}

.card {
  width: min(780px, 100%);
  background: color-mix(in srgb, var(--card), #000 10%);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 22px;
  box-shadow: 0 12px 40px rgba(0,0,0,0.35);
}

h1 {
  margin: 0 0 10px;
  font-size: 1.5rem;
}

.hint {
  margin: 0 0 18px;
  color: var(--muted);
  line-height: 1.4;
}

.hint code {
  background: rgba(255,255,255,0.06);
  border: 1px solid var(--line);
  padding: 2px 6px;
  border-radius: 8px;
}

.grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
}

@media (min-width: 720px) {
  .grid { grid-template-columns: 1fr 1fr; }
}

.field span {
  display: block;
  margin-bottom: 6px;
  color: var(--muted);
  font-size: 0.95rem;
}

input[type="text"] {
  width: 100%;
  padding: 12px 12px;
  border-radius: 12px;
  border: 1px solid var(--line);
  background: rgba(0,0,0,0.18);
  color: var(--text);
  outline: none;
}

input[type="text"]:focus {
  border-color: color-mix(in srgb, var(--accent), white 10%);
  box-shadow: 0 0 0 4px rgba(124, 92, 255, 0.20);
}

.ops {
  margin-top: 16px;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 12px;
}

.ops legend {
  padding: 0 8px;
  color: var(--muted);
}

.ops label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-right: 16px;
  cursor: pointer;
}

button {
  margin-top: 14px;
  width: 100%;
  padding: 12px 14px;
  border-radius: 12px;
  border: 1px solid color-mix(in srgb, var(--accent), #000 40%);
  background: linear-gradient(180deg, color-mix(in srgb, var(--accent), #fff 10%), var(--accent));
  color: white;
  font-weight: 700;
  cursor: pointer;
}

button:hover {
  filter: brightness(1.03);
}

.output {
  margin-top: 18px;
  border-top: 1px solid var(--line);
  padding-top: 16px;
}

.output h2 {
  margin: 0 0 10px;
  font-size: 1.1rem;
}

.result {
  padding: 12px;
  border-radius: 12px;
  border: 1px solid var(--line);
  background: rgba(255,255,255,0.04);
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  font-size: 1.05rem;
  min-height: 44px;
  display: flex;
  align-items: center;
}

.error {
  margin-top: 10px;
  color: var(--danger);
  min-height: 1.2em;
}