If you are looking to do this only in EditMode, then in EditMode kentico adds a "EditMode" class to the body tag, so you can add css prefixed with .EditMode to add styling
ex:
.EditMode .MyWidgetZone {
padding: 20px;
}
The rest is just up to css styling!
If this isn't for EditMode, i would just work with normal CSS to accomplish what you are looking to do.