.fraction-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
  gap: 1rem;
  align-items: center;
}

.fraction-grid fieldset {
  display: grid;
  gap: .45rem;
  min-width: 0;
  margin: 0;
  padding: 1rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
}

.fraction-grid legend {
  padding: 0 .35rem;
  font-weight: 700;
}

.fraction-line {
  display: block;
  height: 2px;
  background: var(--ink);
  opacity: .45;
}

.fraction-operator {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--brand);
}

.scientific-keypad {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: .55rem;
}

.scientific-key {
  min-height: 2.8rem;
  padding: .5rem .3rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--ink);
  font: inherit;
  font-weight: 650;
  cursor: pointer;
}

.scientific-key:hover,
.scientific-key:focus-visible {
  border-color: var(--brand);
  background: var(--surface-soft);
}

.scientific-key-wide {
  color: var(--brand);
}

@media (max-width: 560px) {
  .fraction-grid {
    grid-template-columns: 1fr;
  }

  .fraction-operator {
    text-align: center;
    transform: rotate(90deg);
  }

  .scientific-keypad {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}