margin align css output

```
@for $i from 1 to 3 {
  .b-$i { width: $(i)px; }
}
```

```
  .b-$i { width: $(i)px; }
.b-$i { width: $(i)px; }
.b-$i { width: $(i)px; }
```

I don't know why there is the first blank line and 2nd line has a space.