Whilst being Microsoft platform, still the katas are great https://quantum.microsoft.com/en-us/experience/quantum-katas

If you want go deep, you will need to refresh/learn few key mathematical foundations that form the basis of QC. They are definitely not hard IMHO. If so, then read Michael Nielsen and Isaac Chuang excellent book https://en.wikipedia.org/wiki/Quantum_Computation_and_Quantu...