Outside Label Bg. Opacity

0%: The label background will be completely transparent, and only label text will be visible.
50%: The label background will be semi-translucent.
100%: The label background will be completely opaque.

With this setting, you can adjust the outside label background transparency for this category with a value between 0 and 100. The default value for this property is 0.

Lower opacity values will create a subtle and clean appearance, while higher opacity will ensure the best label legibility: