@spotinst/spinnaker-deck/app/scripts/modules/core/src/cluster/onDemand/onDemandClusterPicker.component.less

Spinnaker-Deck service, forked with support to Spotinst

on-demand-cluster-picker {
  display: block;
  margin-bottom: 20px;
  .dropdown-menu {
    max-height: 50vh;
    overflow-y: auto;
  }
}