:root {
  color-scheme: light;
  --poisson-surface: #fbfaf6;
  --poisson-panel: #fffefa;
  --poisson-ink: #222824;
  --poisson-muted: #687069;
  --poisson-line: #cfd3cc;
  --poisson-line-strong: #9fa79f;
  --poisson-accent: #245b49;
  --poisson-accent-soft: #e2ebe5;
  --poisson-danger: #9b2f2f;
  --poisson-danger-soft: #f8e9e7;
}

.poisson-app {
  color: var(--poisson-ink);
}

.poisson-app *,
.poisson-app *::before,
.poisson-app *::after {
  box-sizing: border-box;
}

.poisson-app button,
.poisson-app input {
  font: inherit;
}

.poisson-app a {
  color: inherit;
}

.poisson-app :focus-visible {
  outline: 3px solid var(--poisson-accent);
  outline-offset: 3px;
}

.poisson-app .intro {
  margin-bottom: 18px;
}

.poisson-app .intro h1 {
  max-width: 920px;
  margin: 8px 0 10px;
  font-size: clamp(1.75rem, 3vw, 2.45rem);
  line-height: 1.2;
}

.poisson-app .eyebrow,
.poisson-app .section-kicker {
  margin: 0 0 5px;
  color: var(--poisson-accent);
  font-size: .78rem;
  font-weight: 780;
  letter-spacing: .08em;
  text-transform: uppercase;
}

.poisson-app .lead {
  max-width: 820px;
  margin: 0;
  line-height: 1.8;
}

.poisson-app .tool-shell,
.poisson-app .calculator-panel,
.poisson-app .explanation-panel,
.poisson-app .input-grid,
.poisson-app .result-details,
.poisson-app .formula-list {
  min-width: 0;
}

.poisson-app .tool-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  border: 1px solid var(--poisson-line-strong);
  background: var(--poisson-surface);
}

.poisson-app .calculator-panel,
.poisson-app .explanation-panel {
  padding: 25px;
}

.poisson-app .calculator-panel {
  border-right: 1px solid var(--poisson-line);
}

.poisson-app h2 {
  margin: 0;
  font-size: clamp(1.2rem, 2vw, 1.48rem);
  line-height: 1.4;
}

.poisson-app h3 {
  margin: 0;
  font-size: 1rem;
}

.poisson-app .input-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 15px;
  margin-top: 20px;
}

.poisson-app .field-group {
  min-width: 0;
}

.poisson-app .field-group label {
  display: block;
  font-size: .86rem;
  font-weight: 760;
}

.poisson-app .field-group input {
  width: 100%;
  min-height: 46px;
  margin-top: 6px;
  padding: 8px 10px;
  border: 1px solid var(--poisson-line-strong);
  border-radius: 0;
  color: var(--poisson-ink);
  background: #fff;
}

.poisson-app .field-group input:focus {
  border-color: var(--poisson-accent);
  outline: 3px solid var(--poisson-accent-soft);
  outline-offset: 0;
}

.poisson-app .field-help {
  min-height: 2.5em;
  margin: 6px 0 0;
  color: var(--poisson-muted);
  font-size: .73rem;
  line-height: 1.55;
  overflow-wrap: anywhere;
}

.poisson-app .form-error {
  margin: 16px 0 0;
  padding: 10px 12px;
  border-left: 4px solid var(--poisson-danger);
  background: var(--poisson-danger-soft);
  color: var(--poisson-danger);
  font-size: .84rem;
  font-weight: 700;
  line-height: 1.6;
  overflow-wrap: anywhere;
}

.poisson-app .form-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 19px;
}

.poisson-app .button {
  min-height: 46px;
  padding: 9px 17px;
  border: 1px solid var(--poisson-accent);
  border-radius: 0;
  cursor: pointer;
  font-weight: 760;
}

.poisson-app .button-primary {
  color: #fff;
  background: var(--poisson-accent);
}

.poisson-app .button-primary:hover {
  background: #1d4d3e;
}

.poisson-app .button-secondary {
  color: var(--poisson-accent);
  background: transparent;
}

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

.poisson-app .result-box {
  margin-top: 20px;
  padding: 17px;
  border: 1px solid var(--poisson-line-strong);
  background: #fff;
}

.poisson-app .result-box[data-state="ready"] {
  border-color: var(--poisson-accent);
}

.poisson-app .result-box[data-state="error"] {
  border-color: var(--poisson-danger);
}

.poisson-app .result-label,
.poisson-app .result-status,
.poisson-app .model-copy {
  margin: 0;
}

.poisson-app .result-label {
  color: var(--poisson-muted);
  font-size: .78rem;
  font-weight: 760;
}

.poisson-app .result-value {
  display: block;
  margin-top: 2px;
  color: var(--poisson-accent);
  font-size: clamp(1.45rem, 3vw, 2.05rem);
  font-weight: 820;
  line-height: 1.35;
  overflow-wrap: anywhere;
}

.poisson-app .result-status {
  margin-top: 4px;
  color: var(--poisson-muted);
  font-size: .82rem;
  line-height: 1.55;
  overflow-wrap: anywhere;
}

.poisson-app .result-details {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin: 16px 0 0;
  border-top: 1px solid var(--poisson-line);
  border-left: 1px solid var(--poisson-line);
}

.poisson-app .result-details > div {
  min-width: 0;
  padding: 9px 10px;
  border-right: 1px solid var(--poisson-line);
  border-bottom: 1px solid var(--poisson-line);
}

.poisson-app .result-details dt {
  color: var(--poisson-muted);
  font-size: .72rem;
  line-height: 1.4;
}

.poisson-app .result-details dd {
  margin: 4px 0 0;
  color: var(--poisson-ink);
  font-size: .95rem;
  font-variant-numeric: tabular-nums;
  font-weight: 760;
  overflow-wrap: anywhere;
}

.poisson-app .explanation-panel {
  background: var(--poisson-panel);
}

.poisson-app .model-copy {
  margin-top: 17px;
  line-height: 1.8;
}

.poisson-app .formula-list {
  display: grid;
  gap: 9px;
  margin-top: 20px;
}

.poisson-app .formula-list article {
  display: grid;
  gap: 3px;
  padding: 12px 13px;
  border-left: 4px solid var(--poisson-accent);
  background: var(--poisson-accent-soft);
}

.poisson-app .formula-list strong {
  font-size: .96rem;
  line-height: 1.5;
  overflow-wrap: anywhere;
}

.poisson-app .formula-list span {
  color: var(--poisson-muted);
  font-size: .78rem;
  line-height: 1.5;
}

.poisson-app .proof-guide {
  margin-top: 22px;
  padding-top: 18px;
  border-top: 1px solid var(--poisson-line);
}

.poisson-app .proof-guide ul {
  margin: 10px 0 0;
  padding-left: 1.2rem;
}

.poisson-app .proof-guide li {
  margin-top: 7px;
  line-height: 1.65;
}

@media (max-width: 800px) {
  .poisson-app .tool-shell {
    grid-template-columns: 1fr;
  }

  .poisson-app .calculator-panel {
    border-right: 0;
    border-bottom: 1px solid var(--poisson-line);
  }
}

@media (max-width: 560px) {
  .poisson-app .calculator-panel,
  .poisson-app .explanation-panel {
    padding: 19px;
  }

  .poisson-app .input-grid,
  .poisson-app .result-details {
    grid-template-columns: 1fr;
  }

  .poisson-app .field-help {
    min-height: 0;
  }

  .poisson-app .form-actions {
    flex-direction: column;
  }

  .poisson-app .button {
    width: 100%;
  }
}