:root {
  --bg: #ffffff;
  --text: #1a1a1a;
  --muted: #666666;
  --border: #d8d8d8;
  --surface: #f6f6f6;
  --accent: #1a1a1a;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.5;
  -webkit-text-size-adjust: 100%;
}

main {
  max-width: 32rem;
  margin: 0 auto;
  padding: 2rem 1.25rem 4rem;
}

h1 {
  font-size: 1.5rem;
  font-weight: 600;
  margin: 0 0 0.75rem;
  letter-spacing: 0.01em;
}

h2 {
  font-size: 0.8125rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
  margin: 0 0 0.625rem;
}

p {
  margin: 0 0 1rem;
}

a {
  color: var(--text);
}

.lede {
  color: var(--muted);
}

.note {
  font-size: 0.875rem;
  color: var(--muted);
}

.section {
  border-top: 1px solid var(--border);
  padding-top: 1.5rem;
  margin-top: 1.5rem;
}

.section:first-of-type {
  border-top: none;
  padding-top: 0;
  margin-top: 0;
}

button {
  font: inherit;
  cursor: pointer;
  border-radius: 6px;
  padding: 0.75rem 1.25rem;
  border: 1px solid var(--accent);
  transition: opacity 0.12s ease;
}

button:disabled {
  opacity: 0.45;
  cursor: default;
}

button:not(:disabled):hover {
  opacity: 0.85;
}

.btn-primary {
  background: var(--accent);
  color: #ffffff;
}

.btn-secondary {
  background: var(--bg);
  color: var(--text);
  border-color: var(--border);
}

.btn-block {
  display: block;
  width: 100%;
}

.btn-row {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.btn-row button {
  flex: 1 1 8rem;
}

input[type="text"] {
  font: inherit;
  width: 100%;
  padding: 0.75rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--surface);
  color: var(--text);
  margin-bottom: 0.5rem;
}

.card {
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface);
  padding: 1.25rem;
}

.number-card {
  display: block;
  width: 100%;
  min-height: 10rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface);
  color: var(--text);
  padding: 1.5rem 1rem;
  text-align: center;
  user-select: none;
  -webkit-user-select: none;
}

.number-card .number-value {
  font-size: 4rem;
  font-weight: 600;
  line-height: 1.1;
  font-variant-numeric: tabular-nums;
}

.number-card .number-hint {
  display: block;
  font-size: 0.875rem;
  color: var(--muted);
  margin-top: 0.5rem;
}

.number-card.is-hidden .number-value {
  font-size: 1.125rem;
  font-weight: 500;
  color: var(--muted);
}

.status {
  font-size: 0.875rem;
  color: var(--muted);
  margin-top: 0.75rem;
  min-height: 1.25rem;
}

.status.is-error {
  color: #a12323;
}

.hidden {
  display: none;
}

footer {
  max-width: 32rem;
  margin: 0 auto;
  padding: 0 1.25rem 2rem;
  font-size: 0.8125rem;
  color: var(--muted);
}