:root {
  color-scheme: light;
  --app-surface: #fbfaf6;
  --app-panel: #fffefa;
  --app-ink: #222824;
  --app-muted: #687069;
  --app-line: #cfd3cc;
  --app-line-strong: #9fa79f;
  --app-accent: #245b49;
  --app-accent-soft: #e2ebe5;
  --app-warm-soft: #f1e7d9;
  --app-danger: #9b2f2f;
  --app-danger-soft: #f8e9e7;
}

* {
  box-sizing: border-box;
}

html,
body {
  max-width: 100%;
  overflow-x: hidden;
}

button,
input,
select {
  font: inherit;
}

a {
  color: inherit;
}

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

.tool-shell,
.calculator-panel,
.info-panel,
.input-row,
.unit-grid,
.result-details,
.constant-list,
.formula-list {
  min-width: 0;
}

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

.calculator-panel,
.info-panel {
  padding: 25px;
}

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

.section-kicker {
  margin: 0 0 5px;
  color: var(--app-accent);
  font-size: 0.76rem;
  font-weight: 780;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

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

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

fieldset {
  margin: 20px 0 0;
  padding: 0;
  border: 0;
}

legend {
  margin-bottom: 10px;
  font-weight: 760;
}

.input-row {
  display: grid;
  gap: 5px;
}

.input-row label {
  display: block;
  font-size: 0.84rem;
  font-weight: 760;
}

.input-row input,
.input-row select {
  width: 100%;
  min-width: 0;
  min-height: 45px;
  padding: 8px 10px;
  border: 1px solid var(--app-line-strong);
  border-radius: 0;
  color: var(--app-ink);
  background: #fff;
}

.input-row input:focus,
.input-row select:focus {
  border-color: var(--app-accent);
  outline: 3px solid var(--app-accent-soft);
  outline-offset: 0;
}

.value-row {
  margin-top: 16px;
}

.unit-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
  align-items: start;
  gap: 9px;
  margin-top: 16px;
}

.unit-arrow {
  align-self: center;
  margin-top: 13px;
  color: var(--app-accent);
  font-size: 1.25rem;
  font-weight: 700;
}

.field-help {
  margin: 0;
  color: var(--app-muted);
  font-size: 0.73rem;
  line-height: 1.55;
  overflow-wrap: anywhere;
}

.form-error {
  margin: 15px 0 0;
  padding: 10px 12px;
  border-left: 4px solid var(--app-danger);
  background: var(--app-danger-soft);
  color: var(--app-danger);
  font-size: 0.84rem;
  font-weight: 700;
  overflow-wrap: anywhere;
}

.form-error[hidden] {
  display: none;
}

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

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

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

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

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

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

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

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

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

.result-label {
  margin: 0;
  color: var(--app-accent);
  font-size: 0.8rem;
  font-weight: 780;
}

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

.result-value {
  display: block;
  margin-top: 3px;
  color: var(--app-accent);
  font-size: clamp(1.45rem, 3.1vw, 2.05rem);
  font-weight: 780;
  line-height: 1.3;
  font-variant-numeric: tabular-nums;
  overflow-wrap: anywhere;
}

.result-status,
.info-lead {
  margin: 0;
  color: var(--app-muted);
  font-size: 0.82rem;
  line-height: 1.55;
  overflow-wrap: anywhere;
}

.result-status {
  margin-top: 5px;
}

.result-details {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin: 15px 0 0;
  border-top: 1px solid rgba(36, 91, 73, 0.35);
  border-left: 1px solid rgba(36, 91, 73, 0.35);
}

.result-details[hidden] {
  display: none;
}

.result-details div {
  min-width: 0;
  padding: 10px;
  border-right: 1px solid rgba(36, 91, 73, 0.35);
  border-bottom: 1px solid rgba(36, 91, 73, 0.35);
}

.result-details .detail-wide {
  grid-column: 1 / -1;
}

.result-details dt {
  color: var(--app-muted);
  font-size: 0.75rem;
  font-weight: 760;
}

.result-details dd {
  margin: 3px 0 0;
  color: var(--app-ink);
  font-size: 0.86rem;
  font-weight: 650;
  line-height: 1.55;
  overflow-wrap: anywhere;
}

.info-lead {
  margin-top: 17px;
  color: var(--app-ink);
  font-size: 0.88rem;
}

.constant-list {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin: 19px 0 0;
  border-top: 1px solid var(--app-line);
  border-left: 1px solid var(--app-line);
}

.constant-list div {
  min-width: 0;
  padding: 11px 12px;
  border-right: 1px solid var(--app-line);
  border-bottom: 1px solid var(--app-line);
}

.constant-list dt {
  color: var(--app-muted);
  font-size: 0.75rem;
}

.constant-list dd {
  margin: 4px 0 0;
  color: var(--app-accent);
  font-size: 0.9rem;
  font-weight: 780;
  line-height: 1.5;
  overflow-wrap: anywhere;
}

.scope-note {
  margin-top: 20px;
  padding: 16px 17px;
  border: 1px solid var(--app-line);
  background: var(--app-warm-soft);
}

.scope-note p {
  margin: 8px 0 0;
  font-size: 0.8rem;
  line-height: 1.6;
  overflow-wrap: anywhere;
}

.content-section {
  margin-top: 43px;
}

.steps-list {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  margin: 17px 0 0;
  padding: 0;
  border-top: 1px solid var(--app-line);
  border-left: 1px solid var(--app-line);
  list-style: none;
  counter-reset: steps;
}

.steps-list li {
  position: relative;
  min-width: 0;
  min-height: 95px;
  padding: 35px 12px 13px;
  border-right: 1px solid var(--app-line);
  border-bottom: 1px solid var(--app-line);
  background: var(--app-surface);
  counter-increment: steps;
  font-size: 0.86rem;
  overflow-wrap: anywhere;
}

.steps-list li::before {
  content: counter(steps, decimal-leading-zero);
  position: absolute;
  top: 8px;
  left: 12px;
  color: var(--app-accent);
  font-size: 0.75rem;
  font-weight: 800;
}

.formula-list {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 8px;
  margin-top: 17px;
}

.formula-list article {
  display: grid;
  gap: 4px;
  min-width: 0;
  padding: 14px 15px;
  border: 1px solid var(--app-line);
  background: var(--app-surface);
}

.formula-list strong {
  font-size: 0.95rem;
  line-height: 1.55;
  overflow-wrap: anywhere;
}

.formula-list span {
  color: var(--app-muted);
  font-size: 0.81rem;
  line-height: 1.55;
  overflow-wrap: anywhere;
}

.proof-guide {
  margin-top: 20px;
  padding: 17px 18px;
  border: 1px solid var(--app-line);
  background: var(--app-surface);
}

.proof-guide ul {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0 22px;
  margin: 10px 0 0;
  padding-left: 1.25em;
  color: var(--app-muted);
  font-size: 0.84rem;
}

.proof-guide li {
  margin-top: 5px;
  overflow-wrap: anywhere;
}

@media (max-width: 900px) {
  .tool-shell {
    grid-template-columns: 1fr;
  }

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

  .steps-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .steps-list li:nth-child(2) {
    border-right: 0;
  }

  .steps-list li:nth-child(-n + 2) {
    border-bottom: 1px solid var(--app-line);
  }

  .formula-list {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (max-width: 760px) {
  .calculator-panel,
  .info-panel {
    padding: 19px 14px;
  }

  .constant-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .formula-list {
    grid-template-columns: 1fr;
  }

  .proof-guide ul {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 460px) {
  .unit-grid {
    grid-template-columns: 1fr;
  }

  .unit-arrow {
    display: none;
  }

  .form-actions .button {
    flex: 1 1 140px;
  }

  .result-details {
    grid-template-columns: 1fr;
  }

  .result-details .detail-wide {
    grid-column: auto;
  }

  .constant-list {
    grid-template-columns: 1fr;
  }

  .steps-list {
    grid-template-columns: 1fr;
  }

  .steps-list li,
  .steps-list li:nth-child(2),
  .steps-list li:nth-child(3) {
    border-right: 0;
    border-bottom: 1px solid var(--app-line);
  }

  .steps-list li:last-child {
    border-bottom: 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}