Better ListView 2.6 newly supports custom spacing between items in Details view:
Custom Spacing between Items
This property has been recently available in other views, but Details view was exception since its selections needed to be treated in different way: They overlap by 1 pixel so that the double border is avoided in neighboring selections:
1 px overlap of items
We have resolved this to get proper behavior with custom spacings and now the spacing can be set the same way as in any other view:
Simply set LayoutItemsCurrent.ElementOuterPadding to have custom horizontal and vertical padding between items.
You can set this specifically for Details view by refering to property LayoutItemsDetails or LayoutItemsDetailsColumns (Details view with columns).