What are the Sharia-compliant controls for the interaction of non-hijabi girls with young men in mixed university activities, and how can they be gradually advised to accept guidance?

The instinctive inclination between men and women necessitates their separation as much as possible. If there is a need for them to gather in one place, then Islamic guidelines must be observed, such as avoiding forbidden mixing, and women refraining from ostentatious display (tabarruj), perfuming themselves, speaking softly, and conversing unnecessarily. The extent of necessity or need is determined by referring to the texts of Islamic law and the words of scholars, not by personal whims. Religion is advice, and advice has its etiquette.