Fix typos in CSS classname

What does this MR do?

Fixes typos in CSS classname, which were introduced in !9417 (merged).

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [n/a] Documentation (if required)
• Code review guidelines
• [n/a] Merge request performance guidelines
• Style guides
• [n/a] Database guides
• Separation of EE specific content