@salesforce-ux/design-system/css/counter/base/index.css

Salesforce Lightning Design System

/*! Lightning Design System 2.12.0 */
@charset "UTF-8";
.slds-input_counter {
  text-align: center;
  padding: 0 3rem;
}
.slds-input_counter[type="number"] {
  -moz-appearance: textfield;
}
.slds-input_counter::-webkit-inner-spin-button {
  -moz-appearance: none;
  -webkit-appearance: none;
  appearance: none;
  margin: 0;
}
.slds-input__button_decrement {
  position: absolute;
  top: 50%;
  -webkit-transform: translateY(-50%);
  transform: translateY(-50%);
  left: 0.75rem;
}
.slds-input__button_increment {
  position: absolute;
  top: 50%;
  -webkit-transform: translateY(-50%);
  transform: translateY(-50%);
  right: 0.75rem;
}