A judge in Hong Kong on Thursday handed down sentences to two editors in a landmark case that showed how a crackdown by China has curtailed press freedoms in the once freewheeling city.

The two journalists, Chung Pui-kuen, and his successor, Patrick Lam, were convicted in August of conspiring to publish seditious materials on Stand News, a now defunct pro-democracy news site. Mr. Chung was sentenced to 21 months, and Mr. Lam, who has a serious health condition, to the time he had already served between his arrest and his release on bail — slightly less than a year.

Stand News, like several other news outlets in Hong Kong, was once an example of the civil liberties the city offered that were unimaginable in the rest of China. It pursued investigations exposing the government’s failures and gave voice to the city’s beleaguered pro-democracy movement.

After antigovernment protests roiled Hong Kong in 2019, Beijing crushed the opposition with a powerful national security law. But Stand News continued to publish pro-democracy voices in editorials and interviews.

The outlet closed after Mr. Chung and Mr. Lam were arrested in December 2021, when hundreds of police officers raided the newsroom and collected boxes of evidence.