: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: #a36b35;
  --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 {
  font: inherit;
}

a {
  color: inherit;
}

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

.intro {
  margin-bottom: 18px;
}

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

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

.lead {
  max-width: 760px;
  margin: 0;
  line-height: 1.8;
}

.tool-shell,
.calculator-panel,
.visual-panel,
.input-grid,
.result-details,
.visual-metrics,
.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,
.visual-panel {
  padding: 25px;
}

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

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

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

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

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

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

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

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

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

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

.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);
}

.result-label,
.result-status {
  margin: 0;
}

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

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

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

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

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

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

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

.result-details dd {
  margin: 3px 0 0;
  font-size: .81rem;
  font-weight: 740;
  line-height: 1.55;
  overflow-wrap: anywhere;
}

.visual-heading-row {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
}

.status-badge {
  flex: 0 0 auto;
  padding: 4px 8px;
  border: 1px solid var(--app-line-strong);
  color: var(--app-muted);
  font-size: .72rem;
  font-weight: 760;
  line-height: 1.45;
  white-space: nowrap;
}

.status-badge[data-state="ready"] {
  border-color: var(--app-accent);
  background: var(--app-accent-soft);
  color: var(--app-accent);
}

.visual-metrics {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin: 19px 0 0;
  border-top: 1px solid var(--app-line);
  border-left: 1px solid var(--app-line);
}

.visual-metrics div {
  min-width: 0;
  padding: 10px;
  border-right: 1px solid var(--app-line);
  border-bottom: 1px solid var(--app-line);
}

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

.visual-metrics dd {
  margin: 3px 0 0;
  font-size: .82rem;
  font-weight: 760;
  line-height: 1.45;
  overflow-wrap: anywhere;
}

.energy-stage {
  display: grid;
  place-items: center;
  min-height: 310px;
  margin-top: 18px;
  padding: 22px 18px;
  border: 1px solid var(--app-line);
  background: #f0f2ed;
}

.energy-figure {
  width: 100%;
  margin: 0;
}

.energy-chart {
  display: grid;
  gap: 7px;
  width: min(100%, 440px);
  margin: 0 auto;
  padding: 10px 0;
}

.energy-level {
  display: grid;
  grid-template-columns: minmax(55px, 72px) minmax(0, 1fr);
  align-items: center;
  gap: 10px;
  min-width: 0;
}

.energy-level-label {
  color: var(--app-muted);
  font-family: ui-monospace, SFMono-Regular, Consolas, monospace;
  font-size: .74rem;
  line-height: 1.35;
  overflow-wrap: anywhere;
}

.energy-level-label b {
  display: block;
  color: var(--app-warm);
  font-family: inherit;
  font-size: .68rem;
  font-weight: 760;
}

.energy-level-line {
  position: relative;
  min-width: 0;
  height: 11px;
  border-top: 2px solid var(--app-line-strong);
}

.energy-level-line::after {
  position: absolute;
  top: -5px;
  right: 0;
  width: 8px;
  height: 8px;
  border: 2px solid var(--app-line-strong);
  border-radius: 50%;
  background: var(--app-panel);
  content: "";
}

.energy-level[data-role="initial"] .energy-level-label {
  color: var(--app-warm);
}

.energy-level[data-role="initial"] .energy-level-line {
  border-color: var(--app-warm);
}

.energy-level[data-role="initial"] .energy-level-line::after {
  border-color: var(--app-warm);
  background: var(--app-warm-soft);
}

.energy-level[data-role="final"] .energy-level-label {
  color: var(--app-accent);
}

.energy-level[data-role="final"] .energy-level-line {
  border-color: var(--app-accent);
}

.energy-level[data-role="final"] .energy-level-line::after {
  border-color: var(--app-accent);
  background: var(--app-accent-soft);
}

.transition-legend {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  margin-top: 8px;
  color: var(--app-warm);
  font-size: .8rem;
  font-weight: 760;
}

.transition-arrow {
  font-size: 1.5rem;
  line-height: 1;
}

.energy-figure figcaption,
.visual-description,
.scale-note {
  color: var(--app-muted);
  font-size: .8rem;
  line-height: 1.65;
}

.energy-figure figcaption {
  margin-top: 13px;
  text-align: center;
}

.visual-description {
  margin: 15px 0 0;
  font-size: .84rem;
}

.scale-note {
  margin: 8px 0 0;
  font-size: .74rem;
}

.content-section {
  margin-top: 46px;
}

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

.formula-list article {
  display: grid;
  gap: 6px;
  min-width: 0;
  padding: 16px;
  border-right: 1px solid var(--app-line);
  border-bottom: 1px solid var(--app-line);
}

.formula-list strong {
  overflow-wrap: anywhere;
}

.formula-list span {
  color: var(--app-muted);
  font-size: .82rem;
  line-height: 1.55;
}

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

.proof-guide ul {
  margin: 10px 0 0;
  padding-left: 1.25em;
}

.proof-guide li {
  line-height: 1.75;
  overflow-wrap: anywhere;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 18px;
}

.footer-links a {
  color: var(--app-accent);
  font-weight: 700;
}

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

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

@media (max-width: 700px) {
  .formula-list {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 520px) {
  .calculator-panel,
  .visual-panel {
    padding: 19px 14px;
  }

  .intro h1 {
    font-size: clamp(1.55rem, 8vw, 2rem);
  }

  .input-grid,
  .result-details,
  .visual-metrics {
    grid-template-columns: 1fr;
  }

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

  .form-actions {
    display: grid;
    grid-template-columns: 1fr;
  }

  .button {
    width: 100%;
  }

  .energy-stage {
    min-height: 270px;
    padding: 18px 10px;
  }

  .energy-level {
    grid-template-columns: minmax(48px, 62px) minmax(0, 1fr);
    gap: 7px;
  }

  .energy-level-label {
    font-size: .68rem;
  }

  .energy-level-label b {
    font-size: .62rem;
  }

  .content-section {
    margin-top: 35px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: .01ms !important;
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
  }
}