:root {
  color-scheme: light;
  --em-accent-strong: #173f32;
  --em-plot: #5c8f9d;
  --em-plot-soft: #dcebed;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
button, input, select { font: inherit; }
a { color: inherit; }
:focus-visible { outline: 3px solid var(--kw-accent); outline-offset: 3px; }

h2 { margin: 0; font-size: clamp(1.2rem, 2vw, 1.48rem); line-height: 1.35; }
h3 { margin: 0; font-size: 1rem; line-height: 1.4; }

.tool-shell {
  display: grid;
  grid-template-columns: minmax(0, .98fr) minmax(0, 1.02fr);
  border: 1px solid var(--kw-line-strong);
  background: var(--kw-surface);
}

.calculator-panel,
.visual-panel { min-width: 0; padding: 24px; }
.calculator-panel { border-right: 1px solid var(--kw-line); }

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

.values-fieldset {
  margin: 17px 0 0;
  padding: 0;
  border: 0;
}
.values-fieldset > legend { margin-bottom: 9px; font-weight: 760; }
.input-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }
.input-row { min-width: 0; }
.input-row label { display: block; margin-bottom: 5px; font-weight: 720; }
.input-wrap {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(88px, .38fr);
  gap: 6px;
}
.plain-input,
.unit-select {
  width: 100%;
  min-width: 0;
  min-height: 44px;
  border: 1px solid var(--kw-line-strong);
  border-radius: 2px;
  padding: 9px 10px;
  color: var(--kw-ink);
  background: var(--kw-surface);
}
.plain-input[aria-invalid="true"] { border-color: var(--kw-danger, #9b2f2f); background: #fff8f8; }
.unit-select { cursor: pointer; }
.field-help { margin: 4px 0 0; color: var(--kw-muted); font-size: .78rem; }
.field-error { min-height: 1.25em; margin: 2px 0 0; color: var(--kw-danger, #9b2f2f); font-size: .78rem; }
.input-note { margin: 14px 0 0; color: var(--kw-muted); font-size: .8rem; }

.form-error {
  margin: 12px 0 0;
  padding: 8px 10px;
  border-left: 4px solid var(--kw-danger, #9b2f2f);
  background: var(--kw-danger-soft, #f8e9e7);
  color: #762525;
}
.form-error[hidden] { display: none; }
.form-actions { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 17px; }
.button {
  min-height: 42px;
  border: 1px solid var(--kw-accent);
  border-radius: 2px;
  padding: 8px 15px;
  cursor: pointer;
  font-weight: 760;
}
.button-primary { background: var(--kw-accent); color: #fff; }
.button-secondary { background: var(--kw-surface); color: var(--kw-accent); }

.result-box {
  margin-top: 20px;
  padding: 15px 16px;
  border: 1px solid var(--kw-accent);
  border-left-width: 4px;
  background: var(--kw-accent-soft);
}
.result-box[data-state="error"] { border-color: var(--kw-danger, #9b2f2f); background: var(--kw-danger-soft, #f8e9e7); }
.result-label { margin: 0; color: var(--kw-accent); font-size: .8rem; font-weight: 780; }
.result-value { display: block; font-size: clamp(1.45rem, 3.2vw, 2.05rem); font-weight: 780; overflow-wrap: anywhere; }
.result-status { margin: 5px 0 0; font-size: .9rem; }
.result-details {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin: 14px 0 0;
  border-top: 1px solid #9db8ad;
  border-left: 1px solid #9db8ad;
}
.result-details[hidden] { display: none; }
.result-details > div { min-width: 0; padding: 9px 10px; border-right: 1px solid #9db8ad; border-bottom: 1px solid #9db8ad; }
.result-details .detail-wide { grid-column: 1 / -1; }
.result-details dt { color: var(--kw-muted); font-size: .76rem; font-weight: 760; }
.result-details dd { margin: 2px 0 0; font-size: .86rem; overflow-wrap: anywhere; }

.visual-heading-row { display: flex; justify-content: space-between; gap: 14px; }
.status-badge {
  flex: none;
  align-self: flex-start;
  padding: 3px 8px;
  border: 1px solid var(--kw-line-strong);
  background: var(--kw-paper);
  color: var(--kw-muted);
  font-size: .75rem;
  font-weight: 760;
}
.status-badge[data-state="ready"] { border-color: var(--kw-accent); background: var(--kw-accent-soft); color: var(--kw-accent); }
.visual-metrics {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin: 15px 0 0;
  border-top: 1px solid var(--kw-line);
  border-left: 1px solid var(--kw-line);
}
.visual-metrics > div { min-width: 0; padding: 9px 10px; border-right: 1px solid var(--kw-line); border-bottom: 1px solid var(--kw-line); }
.visual-metrics dt { color: var(--kw-muted); font-size: .75rem; font-weight: 750; }
.visual-metrics dd { margin: 2px 0 0; font-size: .84rem; font-weight: 700; overflow-wrap: anywhere; }
.visual-stage {
  display: grid;
  place-items: center;
  min-height: 312px;
  margin-top: 15px;
  padding: 20px 14px 14px;
  overflow: hidden;
  border: 1px solid var(--kw-line-strong);
  background: linear-gradient(180deg, #fbfaf6, #edf2f2);
}
.plot-figure { width: 100%; margin: 0; }
.plot-svg { display: block; width: 100%; height: auto; overflow: visible; }
.plot-axis { stroke: var(--kw-line-strong); stroke-width: 1.5; }
.plot-grid-line { stroke: var(--kw-line); stroke-width: 1; stroke-dasharray: 4 5; }
.plot-line { stroke: var(--em-plot); stroke-width: 3; }
.plot-point { stroke: var(--kw-surface); stroke-width: 2; }
.plot-point-one { fill: var(--kw-accent); }
.plot-point-two { fill: var(--em-plot); }
.plot-label { fill: var(--kw-ink); font-size: 14px; font-weight: 700; text-anchor: middle; }
.plot-label-target { fill: var(--em-plot); }
.plot-axis-label { fill: var(--kw-muted); font-size: 13px; font-weight: 700; }
.plot-scale-label { fill: var(--kw-muted); font-size: 11px; }
.plot-target-guide { stroke: var(--em-plot); stroke-width: 1.5; stroke-dasharray: 5 5; opacity: .72; }
.visual-caption,
.visual-description,
.scale-note { margin: 9px 0 0; color: var(--kw-muted); font-size: .8rem; }
.visual-caption { text-align: center; }
.visual-description { font-size: .86rem; }
.scale-note { font-size: .75rem; }

.content-section { margin-top: 42px; }
.formula-list {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin-top: 16px;
  border-top: 1px solid var(--kw-line);
  border-left: 1px solid var(--kw-line);
}
.formula-list article { display: grid; gap: 4px; min-width: 0; padding: 14px 15px; border-right: 1px solid var(--kw-line); border-bottom: 1px solid var(--kw-line); }
.formula-list strong { overflow-wrap: anywhere; }
.formula-list span { color: var(--kw-muted); font-size: .82rem; }
.example-box,
.proof-guide {
  margin-top: 20px;
  padding: 17px 18px;
  border: 1px solid var(--kw-line);
  background: var(--kw-surface);
}
.example-box p { margin: 8px 0 0; overflow-wrap: anywhere; }
.proof-guide ul { margin: 10px 0 0; padding-left: 1.25em; }

@media (max-width: 760px) {
  .tool-shell { grid-template-columns: 1fr; }
  .calculator-panel { border-right: 0; border-bottom: 1px solid var(--kw-line); }
}

@media (max-width: 620px) {
  .input-grid,
  .formula-list { grid-template-columns: 1fr; }
  .visual-metrics { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 460px) {
  .calculator-panel,
  .visual-panel { padding: 18px 14px; }
  .input-wrap { grid-template-columns: minmax(0, 1fr) minmax(82px, .38fr); }
  .result-details { grid-template-columns: 1fr; }
  .result-details .detail-wide { grid-column: auto; }
  .visual-stage { min-height: 260px; padding: 14px 8px 10px; }
  .visual-metrics { grid-template-columns: 1fr; }
}