China "took over" nothing. They always were the owners of Hong Kong, they leased it to Britain, the lease was up.
The lease was a “99 year lease” which, under common law, is the longest possible lease, used in lieu of indefinite duration. And it would have been more appropriate to return Hong Kong to Taiwan since the lease (last of three) was made with Qing China. Instead the Handover was to the People’s Republic of China, a revolutionary government which ironically doesn’t brook any criticism of its own rule.