ferngully-aurelia-tools/dist/native-modules/resources/customElements/bootstrap-number-input/spinner.css

Ferngully Tools for Aurelia

.spinner {
  width: inherit;
  display: inline-block;
    white-space: nowrap;
    margin: auto; /* so will center */
}
.spinner input {
  text-align: right;
}
.input-group-btn-vertical {
  position: relative;
  white-space: nowrap;
  width: 1%;
  vertical-align: middle;
  display: inline-block;
}
.input-group-btn-vertical > .btn {
  display: block;
  float: none;
  width: 100%;
  max-width: 100%;
  padding: 8px;
  margin-left: -1px;
  position: relative;
  border-radius: 0;
}
.input-group-btn-vertical > .btn:first-child {
  border-top-right-radius: 4px;
}
.input-group-btn-vertical > .btn:last-child {
  margin-top: -2px;
  border-bottom-right-radius: 4px;
}
.input-group-btn-vertical i{
  position: absolute;
  top: 0;
  left: 4px;
}