Illegal Nesting Error

[ghost]

I'm trying to nest a button on hover but when I save and compile I receive this error:

{
"status": 1,
"file": "/Users/name/Documents/GitHub/projectName/css/style.sass",
"line": 14,
"column": 5,
"message": "Illegal nesting: Only properties may be nested beneath properties.",
"formatted": "Error: Illegal nesting: Only properties may be nested beneath properties.\n on line 14 of Users/name/Documents/GitHub/projectName/css/style.sass\n>> &:hover {\n\n ----^\n"
}

Here is my code:

.btn-orange
  background: $orange-dark
  border: 1px solid $orange-dark
  color: white
    &:hover
      background: $orange
      border: 1px solid $orange
      color: white