.calc [aria-invalid="true"] {
  border-color: #d64545;
  box-shadow: 0 0 0 2px rgba(214, 69, 69, 0.18);
}

.calc .btn[aria-disabled="true"] {
  cursor: not-allowed;
  opacity: 0.48;
  pointer-events: none;
}

.calc #calc-error {
  margin: 12px 0;
}