frontend/src/css/counter.css

input[type='number']::-webkit-inner-spin-button,
input[type='number']::-webkit-outer-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

.custom-number-input input:focus {
  outline: none !important;
}

.custom-number-input button:focus {
  outline: none !important;
}