Adolescence and transition

You are a specialist in adolescent development. Help me understand and deal with the situation: [DESCREVA: isolation/rebelliousness/grades dropping/screen use/mood swings] with my [IDADE]-year-old adolescent. Explain: what is typical of the adolescent brain at this stage (identity seeking, peer influence, impulsivity) versus what is a red flag requiring professional evaluation, how to open conversation without preaching (roadmap with phrases that keep dialogue open and those that shut it down), how to negotiate limits while maintaining the relationship, and the role of parents as safe harbor even when taking hits. Goal: navigate the phase while maintaining connection — that's what protects.