Why don't nested SCSS properties compile?

Question

css

border: {
      width: 2px;
      style: solid;
      color: $secondary;
    }

Why doesn't compilation to .scss work for me?
Mistake:

Error: Invalid CSS after "		border:": expected expression (e.g. 1px, bold), was "}"

Answer 1

Nested properties must be inside the selector, sort of like

.classname {
  border: {
      width: 2px;
      style: solid;
      color: $secondary;
    }
}