:root {
  --bg: #EAEDE9;
  --surface: #FFFFFF;
  --surface-sunken: #F2F4F0;
  --ink: #1B2320;
  --ink-soft: #5B6660;
  --ink-faint: #8A948D;
  --line: #CDD5CD;
  --line-strong: #B4BEB3;
  --accent: #C96A1F;
  --accent-ink: #FFFBF5;
  --accent-soft: #F3E3D2;
  --focus: #2F6E5C;
  --shadow: 0 1px 2px rgba(27, 35, 32, 0.06), 0 8px 24px -12px rgba(27, 35, 32, 0.18);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #121815;
    --surface: #1A211D;
    --surface-sunken: #161C19;
    --ink: #ECEFEA;
    --ink-soft: #A3AEA6;
    --ink-faint: #71796F;
    --line: #2A332C;
    --line-strong: #3A4640;
    --accent: #E38A3F;
    --accent-ink: #1B140C;
    --accent-soft: #3A2917;
    --focus: #6FBFA4;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 12px 32px -16px rgba(0, 0, 0, 0.6);
  }
}

:root[data-theme="dark"] {
  --bg: #121815;
  --surface: #1A211D;
  --surface-sunken: #161C19;
  --ink: #ECEFEA;
  --ink-soft: #A3AEA6;
  --ink-faint: #71796F;
  --line: #2A332C;
  --line-strong: #3A4640;
  --accent: #E38A3F;
  --accent-ink: #1B140C;
  --accent-soft: #3A2917;
  --focus: #6FBFA4;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 12px 32px -16px rgba(0, 0, 0, 0.6);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: "IBM Plex Sans", system-ui, -apple-system, sans-serif;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

.page {
  max-width: 42rem;
  margin: 0 auto;
  padding: 3rem 1.5rem 5rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

header.intro {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.eyebrow {
  font-family: "IBM Plex Mono", ui-monospace, monospace;
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 500;
}

h1 {
  font-family: "Fraunces", Georgia, serif;
  font-optical-sizing: auto;
  font-weight: 600;
  font-size: clamp(1.9rem, 4.5vw, 2.6rem);
  margin: 0;
  letter-spacing: -0.01em;
  text-wrap: balance;
  color: var(--ink);
}

.lede {
  margin: 0;
  max-width: 34rem;
  color: var(--ink-soft);
  font-size: 0.98rem;
}

.lede code {
  font-family: "IBM Plex Mono", monospace;
  background: var(--surface-sunken);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 0.05em 0.35em;
  font-size: 0.9em;
  color: var(--ink);
}

.panel {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 10px;
  box-shadow: var(--shadow);
}

.control-panel {
  padding: 1.25rem 1.5rem;
  display: flex;
  align-items: flex-end;
  gap: 1rem;
  flex-wrap: wrap;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.field label {
  font-size: 0.78rem;
  font-weight: 500;
  color: var(--ink-soft);
  letter-spacing: 0.02em;
}

.field-row {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

input[type="number"] {
  font-family: "IBM Plex Mono", monospace;
  font-size: 1.3rem;
  font-variant-numeric: tabular-nums;
  width: 5rem;
  padding: 0.5rem 0.6rem;
  border-radius: 7px;
  border: 1px solid var(--line-strong);
  background: var(--surface-sunken);
  color: var(--ink);
}

input[type="number"]:focus-visible,
button:focus-visible {
  outline: 2px solid var(--focus);
  outline-offset: 2px;
}

.hint {
  font-size: 0.8rem;
  color: var(--ink-faint);
}

button.primary {
  font-family: "IBM Plex Sans", sans-serif;
  font-weight: 600;
  font-size: 0.92rem;
  background: var(--accent);
  color: var(--accent-ink);
  border: none;
  border-radius: 7px;
  padding: 0.62rem 1.15rem;
  cursor: pointer;
  transition: filter 0.15s ease, transform 0.1s ease;
}

button.primary:hover { filter: brightness(1.08); }
button.primary:active { transform: translateY(1px); }

.readout-panel {
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}

.readout-label {
  font-size: 0.8rem;
  color: var(--ink-soft);
  font-weight: 500;
}

.readout-value {
  font-family: "IBM Plex Mono", monospace;
  font-variant-numeric: tabular-nums;
  font-weight: 600;
  font-size: clamp(1.8rem, 5.5vw, 2.6rem);
  color: var(--ink);
  word-break: break-all;
  line-height: 1.15;
}

.readout-formula {
  font-family: "IBM Plex Mono", monospace;
  font-size: 0.82rem;
  color: var(--ink-faint);
}

.results-panel {
  padding: 1.25rem 1.5rem 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.results-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1rem;
  flex-wrap: wrap;
  border-bottom: 1px solid var(--line);
  padding-bottom: 0.75rem;
}

.results-header h2 {
  font-family: "IBM Plex Sans", sans-serif;
  font-size: 0.95rem;
  font-weight: 600;
  margin: 0;
  color: var(--ink);
}

.results-count {
  font-family: "IBM Plex Mono", monospace;
  font-size: 0.82rem;
  color: var(--ink-soft);
  font-variant-numeric: tabular-nums;
}

.code-grid {
  --code-len: 4;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(max(5.6rem, calc(var(--code-len) * 1ch + 1.6rem)), 1fr));
  gap: 0.5rem;
  max-height: 26rem;
  overflow-y: auto;
  overflow-x: auto;
  padding: 0.25rem;
}

.code-chip {
  font-family: "IBM Plex Mono", monospace;
  font-variant-numeric: tabular-nums;
  font-size: 0.92rem;
  white-space: nowrap;
  text-align: center;
  background: var(--surface-sunken);
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 0.45rem 0.3rem;
  color: var(--ink);
}

.load-more-row {
  display: flex;
  justify-content: center;
  padding-top: 0.25rem;
}

button.secondary {
  font-family: "IBM Plex Sans", sans-serif;
  font-weight: 500;
  font-size: 0.88rem;
  background: transparent;
  color: var(--accent);
  border: 1px solid var(--line-strong);
  border-radius: 7px;
  padding: 0.55rem 1.3rem;
  cursor: pointer;
}

button.secondary:hover { background: var(--accent-soft); }

button.secondary:disabled {
  opacity: 0.5;
  cursor: default;
  background: transparent;
}

.done-note {
  text-align: center;
  font-size: 0.82rem;
  color: var(--ink-faint);
  font-family: "IBM Plex Mono", monospace;
}

footer.note {
  font-size: 0.82rem;
  color: var(--ink-faint);
  border-top: 1px solid var(--line);
  padding-top: 1.25rem;
}

@media (max-width: 30rem) {
  .control-panel { flex-direction: column; align-items: stretch; }
  button.primary { width: 100%; }
}