.desk {
  display: grid;
  grid-template-columns: 7fr 5fr;
  gap: 18px;
  align-items: stretch;
}
.desk-inputs, .formula-box, .tool-index, .mini-desk, .entry, .example-row {
  background: var(--paper);
  border: 1px solid var(--border);
  padding: 20px;
}
.frac-pair {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
  align-items: center;
}
.frac-input {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  min-width: 120px;
}
.frac-input label {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
}
.frac-input input, .field input, .field select {
  font-family: var(--mono);
  font-variant-numeric: tabular-nums;
  font-size: 22px;
  width: 120px;
  min-height: 48px;
  text-align: center;
  border: 1px solid var(--border);
  background: #fff;
  color: var(--ink);
}
.frac-bar {
  display: block;
  width: 88px;
  height: 3px;
  background: var(--ink);
}
.ops {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}
.ops button[aria-pressed="true"] {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}
.actions { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 16px; }

.desk-result {
  background: var(--result);
  color: #F5F2EA;
  padding: 22px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.desk-result .kicker { color: #C9D4D1; }
.big-frac {
  color: #FFFEFA;
  min-height: 4.5rem;
}
.frac-stack {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  font-family: var(--mono);
  font-variant-numeric: tabular-nums;
}
.frac-stack .n, .frac-stack .d {
  font-size: clamp(48px, 7vw, 96px);
  line-height: 1;
}
.frac-stack .bar {
  width: 100%;
  min-width: 1.4em;
  height: 4px;
  background: currentColor;
  margin: 8px 0;
}
.int-result {
  font-family: var(--mono);
  font-size: clamp(48px, 7vw, 96px);
  line-height: 1;
}
.desk-result p { margin: 0; font-size: 14px; color: #D7E0DD; }
.desk-result select {
  background: #1c2f33;
  color: #FFFEFA;
  border: 1px solid #3d555c;
  min-height: 40px;
}

.steps { background: var(--highlight); border: 1px solid var(--border); padding: 20px; margin-top: 16px; }
.steps ol { padding-left: 1.2em; }
.steps li { margin: 10px 0; }
.field { display: flex; flex-direction: column; gap: 6px; margin: 8px 0; }
.field label { font-size: 11px; letter-spacing: 0.12em; text-transform: uppercase; color: var(--muted); }

.tool-tabs {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
}
.tool-tab {
  appearance: none;
  text-align: left;
  border: 1px solid var(--border);
  background: #fff;
  padding: 12px;
  cursor: pointer;
  min-height: 88px;
  color: inherit;
}
.tool-tab strong { display: block; font-family: var(--serif); font-size: 17px; }
.tool-tab span { display: block; font-size: 13px; color: var(--muted); }
.tool-tab.is-active { border-color: var(--accent); box-shadow: inset 3px 0 0 var(--accent); }

.mini-desk { margin-top: 12px; }
.example-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 12px; }
.example-q { font-family: var(--serif); font-size: 18px; }
.example-a { font-family: var(--mono); font-size: 22px; }
.formula-list { display: grid; gap: 14px; }

@media (max-width: 760px) {
  .desk { grid-template-columns: 1fr; }
  .tool-tabs, .example-grid { grid-template-columns: 1fr; }
  .tool-tabs { display: flex; overflow-x: auto; padding-bottom: 8px; }
  .tool-tab { min-width: 210px; flex: 0 0 auto; }
  .frac-stack .n, .frac-stack .d, .int-result { font-size: clamp(48px, 12vw, 64px); }
}