Babylon.js/inspector/sass/_resizeBar.scss

.c2di-resize-bar-v {
  height:100%;
  width:$resizebar-width;
  background-color: $background;
  cursor: col-resize;
  flex-shrink: 0;
  border-left:1px solid $background-lighter;
  border-right:1px solid $background-lighter;
}
.c2di-resize-bar-h {
  width:100%;
  height:$resizebar-width;
  background-color: $background;
  cursor: row-resize;
  flex-shrink: 0;
  border-top: 1px solid $background-lighter;
  border-bottom: 1px solid $background-lighter;
}