Mark was finishing a helper tool for the team to use when customizing their dashboard layout settings. Eva noticed during the code review that the tool occasionally let through mismatched styling markers, which was causing the interface to glitch. He needs to make sure that every bracket, whether round, square, or curly, is perfectly balanced and closed in the exact order it was opened. As an example, a sequence like "([])" should pass the check, but "([)]" needs to be caught as a mistake before the settings are saved.