:root {
  --bg: #0b0b0c;
  --fg: #d9d7d0;
  --dim: #6b6860;
  --accent: #c8a96a;
  --ok: #7fb069;
  --bad: #b05050;
  --mono: ui-monospace, "SF Mono", "JetBrains Mono", Menlo, monospace;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--mono);
  font-size: 15px;
  line-height: 1.5;
}

main {
  max-width: 560px;
  margin: 6vh auto;
  padding: 0 1.25rem;
}

header h1 {
  font-size: 3rem;
  margin: 0;
  color: var(--accent);
  text-align: center;
}

header .sub {
  color: var(--dim);
  text-align: center;
  margin-top: 0.25rem;
}

.grid {
  display: grid;
  gap: 0.5rem;
  margin-top: 2rem;
}

.row {
  display: grid;
  grid-template-columns: 2.5rem 1fr 1.5rem;
  align-items: center;
  gap: 0.5rem;
  padding: 0.35rem 0.5rem;
  border: 1px solid #1e1e20;
  background: #111113;
}

.num {
  color: var(--dim);
  text-align: right;
  user-select: none;
}

input[type=text] {
  background: transparent;
  border: none;
  color: var(--fg);
  font-family: var(--mono);
  font-size: 1rem;
  outline: none;
  width: 100%;
  padding: 0.25rem 0;
}

.row.ok  { border-color: var(--ok); }
.row.bad { animation: shake 0.3s; }
.row.ok  .mark::before { content: "✓"; color: var(--ok); }
.row.bad .mark::before { content: "·"; color: var(--bad); }

@keyframes shake {
  0%,100% { transform: translateX(0); }
  25%     { transform: translateX(-3px); }
  75%     { transform: translateX(3px); }
}

.status {
  min-height: 1.25rem;
  color: var(--dim);
  margin-top: 1rem;
  text-align: center;
}

footer {
  margin-top: 3rem;
  text-align: center;
}
footer .hint {
  color: var(--dim);
  font-size: 0.8rem;
}