.okp-product-calculator {
  max-width: 520px;
  padding: 16px;
  margin: 24px 0;
  border: 1px solid #e2e2e2;
  border-radius: 8px;
  font-family: Arial, sans-serif;
}
.okp-product-calculator h3 {
  margin-top: 0;
  margin-bottom: 8px;
}
.okp-product-calculator p {
  margin: 4px 0;
}
.okp-size-inputs input {
  width: 90px;
  padding: 4px;
  margin: 4px;
}
#okp-calc-btn {
  margin-top: 10px;
  padding: 8px 16px;
  cursor: pointer;
}
.okp-result {
  margin-top: 12px;
  padding: 10px;
  border-radius: 6px;
  background: #f7f7f7;
  white-space: pre-line;
}