CSS indentation incorrect on blank lines

[stevemolitor]

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This is reminiscent of #8 . When adding a new line in CSS or if the line is blank it does not indent correctly:

.myBox {
  display: flex;
  flex-direction: row;
|
^ cursor is here after indenting, should be two spaces to the right
}

This happens after typing C-j for example on the previous line. As soon as you add even a single character it is indented correctly:

.myBox {
  display: flex;
  flex-direction: row;
  x
  |
  ^ cursor is here
}

I can probably do something similar to #9 to fix, but in tsi-css.el.