Simplifiers for repeat styling

When individually styling panels, I've found that...
1. I want to be able to control exactly how much padding I add, so having a readout to tell me a number would be good.
2. I want to add the same styling to multiple panels, so copy and paste of styles would be cool.
3. Similarly, a (somehow) multi-select option that allows me to style several panels at once. Perhaps style all children of a panel, or all siblings of a panel the same (_maybe_ a special option to "apply style to all children or apply style to all siblings in the edit modal).