Take a look at the following screenshot:
As I understand it there are two broad groups of languages: preferred and all. All languages has subgroups, i.e. languages with variants separated from the rest of the languages. The separation looks similar to how the two broad groups are separated. The headings and paddings above look the same. This makes me think that the languages with variants are not part of the all languages, and the languages that follow are not part of any grouping.
Lets make the background color for the section header same as the cell (#FFF)