// Focus state mixin
@mixin focus-outline(
  $width: $theme-focus-width,
  $style: $theme-focus-style,
  $color: $theme-focus-color,
  $offset: $theme-focus-offset,
) {
  $width: if(
    $width == null,
    $theme-focus-width,
    $width
  );
  $style: if(
    $style == null,
    $theme-focus-style,
    $style
  );
  $color: if(
    $color == null,
    $theme-focus-color,
    $color
  );
  $offset: if(
    $offset == null,
    $theme-focus-offset,
    $offset
  );
  outline: units($width) $style color($color);
  outline-offset: units($offset);
}