Details

Place @else statements on the same line as the preceding curly brace.

Bad

@if {
  ...
}
@else {
  ...
}

Good

@if {
  ...
} @else {
  ...
}

This will ignore single line @if/@else blocks, so you can write:

@if { ... } @else { ... }

You can prefer to enforce having @else on its own line by setting the style configuration option to new_line.