message: fix: use border thin for material theme
  closes
diff: @@ -64,7 +64,7 @@ $ng-select-bg: #ffffff !default;
  align-items: baseline;
  min-height: 51.5px;
  &:after {
  - border-bottom: 1px solid rgba(0, 0, 0, .42);
  + border-bottom: thin solid rgba(0, 0, 0, .42);
  content: '';
  width: 100%;
  bottom: 0;
  