:root {
  --tool-blue: #163f63;
  --tool-blue-dark: #0f2f4a;
  --tool-teal: #2d718f;
  --tool-focus: #b76f00;
  --tool-panel: #ffffff;
  --tool-shadow: 0 18px 50px rgba(23, 37, 51, 0.09);
  --particle-colour: #9a5a13;
  --fluid-colour: #26708f;
  --deformation-colour: #79578f;
  --material-colour: #267a66;
}

.tool-header {
  min-height: 4.75rem;
}

.tool-nav {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-left: auto;
}

.tool-nav a {
  display: inline-flex;
  min-height: 2.75rem;
  align-items: center;
  padding: 0.5rem 0.8rem;
  color: var(--color-muted);
  border-radius: 0.3rem;
  font-size: 0.9rem;
  font-weight: 650;
  text-decoration: none;
}

.tool-nav a:hover {
  color: var(--tool-blue);
  background: var(--color-soft);
}

.dimensionless-main {
  width: min(100% - 3rem, 1260px);
}

.eyebrow {
  margin: 0 0 0.55rem;
  color: var(--tool-teal);
  font-size: 0.78rem;
  font-weight: 750;
  letter-spacing: 0.13em;
  text-transform: uppercase;
}

.tool-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 2rem;
}

.tool-heading > div {
  min-width: 0;
  flex: 1 1 auto;
}

.tool-heading h1 {
  width: min(100%, 820px);
}

.privacy-note {
  display: inline-flex;
  flex: 0 0 auto;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1.6rem;
  color: #3d6154;
  font-size: 0.83rem;
  font-weight: 650;
}

.privacy-note span {
  color: #2f8a65;
  font-size: 0.7rem;
}

.calculator-workspace {
  display: grid;
  grid-template-columns: minmax(360px, 0.88fr) minmax(0, 1.12fr);
  gap: 1.25rem;
  margin-top: 2.5rem;
  align-items: start;
}

.tool-panel {
  min-width: 0;
  padding: clamp(1.15rem, 2.2vw, 1.65rem);
  border: 1px solid var(--color-line);
  border-radius: 0.55rem;
  background: var(--tool-panel);
  box-shadow: var(--tool-shadow);
}

.panel-heading {
  display: flex;
  min-height: 2.25rem;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 0.75rem;
}

.panel-heading h2 {
  margin: 0;
  padding: 0;
  border: 0;
  font-size: 1.08rem;
}

.step-label {
  margin: 0 0 0.12rem;
  color: var(--tool-teal);
  font-size: 0.67rem;
  font-weight: 750;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.panel-intro {
  margin: 0 0 1rem;
  color: var(--color-muted);
  font-size: 0.76rem;
}

.input-group {
  margin-top: 0.75rem;
  border: 1px solid #d8e0e6;
  border-radius: 0.42rem;
  background: #fff;
}

.input-group summary {
  padding: 0.8rem 0.9rem;
  color: var(--tool-blue);
  background: #f6f8fa;
  font-size: 0.82rem;
  font-weight: 750;
  cursor: pointer;
}

.input-group[open] summary {
  border-bottom: 1px solid #dde4e9;
}

.input-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.9rem;
  padding: 1rem;
}

.control-wide {
  grid-column: 1 / -1;
}

.control-field {
  display: flex;
  min-width: 0;
  flex-direction: column;
  gap: 0.38rem;
  color: #344555;
  font-size: 0.8rem;
  font-weight: 700;
}

.control-field > label:first-child,
.control-field > span:first-child {
  min-height: 1.5rem;
}

.control-field small {
  color: var(--color-muted);
  font-size: 0.72rem;
  font-weight: 550;
}

.value-unit,
.value-suffix {
  display: grid;
  min-width: 0;
  grid-template-columns: minmax(0, 1fr) auto;
}

.value-unit input,
.value-suffix input,
.value-unit select {
  min-width: 0;
  min-height: 2.55rem;
  padding: 0.45rem 0.58rem;
  color: var(--color-ink);
  border: 1px solid #c3cdd5;
  background: #fff;
  font: inherit;
  font-size: 0.82rem;
  font-weight: 550;
}

.value-unit input,
.value-suffix input {
  border-radius: 0.3rem 0 0 0.3rem;
}

.value-unit select {
  max-width: 7rem;
  margin-left: -1px;
  border-radius: 0 0.3rem 0.3rem 0;
}

.value-suffix > span {
  display: inline-flex;
  min-width: 4.6rem;
  align-items: center;
  justify-content: center;
  padding: 0.35rem 0.5rem;
  color: #566777;
  border: 1px solid #c3cdd5;
  border-left: 0;
  border-radius: 0 0.3rem 0.3rem 0;
  background: #f6f8fa;
  font-size: 0.74rem;
  font-weight: 600;
  white-space: nowrap;
}

.control-field input:focus-visible,
.control-field select:focus-visible,
.button:focus-visible,
.filter-button:focus-visible,
.input-group summary:focus-visible {
  position: relative;
  z-index: 1;
  outline: 3px solid var(--tool-focus);
  outline-offset: 1px;
}

.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
  margin-bottom: 1rem;
}

.filter-button {
  min-height: 2.25rem;
  padding: 0.4rem 0.7rem;
  color: #4c5d6b;
  border: 1px solid #c8d2d9;
  border-radius: 999px;
  background: #fff;
  font: inherit;
  font-size: 0.78rem;
  font-weight: 700;
  cursor: pointer;
}

.filter-button:hover {
  color: var(--tool-blue);
  background: #f4f7f9;
}

.filter-button[aria-pressed="true"] {
  color: #fff;
  border-color: var(--tool-blue);
  background: var(--tool-blue);
}

.result-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.75rem;
}

.number-card {
  min-width: 0;
  padding: 0.9rem;
  border: 1px solid #d8e0e6;
  border-top: 3px solid var(--tool-teal);
  border-radius: 0.38rem;
  background: #fff;
}

.number-card[hidden] {
  display: none;
}

.number-card[data-category="particle"] {
  border-top-color: var(--particle-colour);
}

.number-card[data-category="fluid"] {
  border-top-color: var(--fluid-colour);
}

.number-card[data-category="deformation"] {
  border-top-color: var(--deformation-colour);
}

.number-card[data-category="material"] {
  border-top-color: var(--material-colour);
}

.number-category {
  margin: 0 0 0.3rem;
  color: var(--color-muted);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.025em;
}

.number-card-heading {
  display: flex;
  align-items: start;
  justify-content: space-between;
  gap: 0.7rem;
}

.number-card h3 {
  margin: 0;
  padding: 0;
  border: 0;
  font-size: 0.86rem;
}

.number-symbol {
  flex: 0 0 auto;
  color: var(--color-muted);
  font-family: Georgia, "Times New Roman", serif;
  font-size: 0.82rem;
  font-style: italic;
}

.number-value {
  min-height: 2.05rem;
  margin: 0.5rem 0 0.2rem;
  color: var(--tool-blue);
  font-size: clamp(1.05rem, 2.6vw, 1.35rem);
  font-weight: 760;
  font-variant-numeric: tabular-nums;
  line-height: 1.3;
}

.number-card[data-ready="false"] .number-value {
  color: var(--color-muted);
  font-size: 0.88rem;
  font-weight: 650;
}

.number-meaning,
.number-formula,
.number-convention {
  margin: 0;
  color: #536472;
  font-size: 0.75rem;
  line-height: 1.5;
}

.number-formula {
  margin-top: 0.5rem;
  color: #344a5a;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-size: 0.72rem;
  overflow-wrap: anywhere;
}

.number-convention {
  margin-top: 0.35rem;
  color: var(--color-muted);
}

.result-actions {
  display: flex;
  justify-content: flex-end;
  margin-top: 1rem;
}

.tool-status {
  color: #2f7157;
  font-size: 0.76rem;
  text-align: right;
}

.button {
  display: inline-flex;
  min-height: 2.6rem;
  align-items: center;
  justify-content: center;
  padding: 0.52rem 0.85rem;
  border: 1px solid transparent;
  border-radius: 0.32rem;
  font: inherit;
  font-size: 0.78rem;
  font-weight: 700;
  cursor: pointer;
}

.button-primary {
  color: #fff;
  border-color: var(--tool-blue);
  background: var(--tool-blue);
}

.button-primary:hover {
  border-color: var(--tool-blue-dark);
  background: var(--tool-blue-dark);
}

.button-quiet {
  color: var(--tool-blue);
  border-color: #c5d0d7;
  background: #fff;
}

.button-quiet:hover {
  background: var(--color-soft);
}

.error-message {
  margin: 0.8rem 0 0;
  color: #9a3b35;
  font-size: 0.76rem;
}

.calculator-help {
  margin-top: 3.75rem;
}

.help-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0.9rem;
}

.help-grid article {
  padding: 1rem;
  border: 1px solid var(--color-line);
  border-radius: 0.4rem;
  background: #fff;
}

.help-grid h3 {
  margin: 0 0 0.55rem;
  padding: 0;
  border: 0;
  font-size: 0.92rem;
}

.help-grid p,
.source-note {
  margin: 0;
  color: #4d5e6d;
  font-size: 0.76rem;
  line-height: 1.65;
}

.source-note {
  max-width: none;
  margin-top: 1rem;
}

.tool-footer {
  display: flex;
  width: min(100% - 3rem, var(--header-width));
  margin: 0 auto;
  padding: 1.5rem 0 2.5rem;
  justify-content: space-between;
  gap: 1rem;
  color: var(--color-muted);
  border-top: 1px solid var(--color-line);
  font-size: 0.78rem;
}

.tool-footer > a {
  font-weight: 700;
}

@media (max-width: 1050px) {
  .calculator-workspace {
    grid-template-columns: 1fr;
  }

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

@media (max-width: 800px) {
  .tool-header {
    display: flex;
    padding: 0.8rem 1.25rem;
  }

  .tool-header .site-name {
    margin: 0;
  }

  .tool-nav {
    margin-top: 0;
  }
}

@media (max-width: 680px) {
  .dimensionless-main {
    width: min(100% - 2rem, 1260px);
  }

  .tool-heading {
    display: block;
  }

  .privacy-note {
    margin: -0.8rem 0 1.5rem;
  }

  .value-unit input,
  .value-suffix input,
  .value-unit select {
    font-size: 1rem;
  }

  .input-grid,
  .result-grid,
  .help-grid {
    grid-template-columns: 1fr;
  }

  .panel-heading {
    align-items: start;
  }

  .tool-footer {
    width: min(100% - 2rem, var(--header-width));
    flex-direction: column;
  }
}

@media (max-width: 430px) {
  .header-inner {
    width: min(100% - 2rem, var(--header-width));
    gap: 0.5rem;
  }

  .tool-nav a {
    padding-inline: 0.45rem;
    font-size: 0.78rem;
  }

  .site-name span {
    display: none;
  }

  .input-group .input-grid {
    padding: 0.8rem;
  }
}

@media (pointer: coarse) {
  .filter-button,
  .button {
    min-height: 2.75rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}