The pristine presentation of Blu-ray might seem at odds with the scuzzy squalor of a seminal punk biopic, but then, Sid and Nancy doesn’t exactly shy away from bracing clarity. With as much anarchic vitality and shrewd humor as a movie about gradual mutual suicide can have, director Alex Cox’s 1986 film recounts the violent and doomed romance between Sex Pistols’ bassist Sid Vicious and his beloved fellow heroin fiend Nancy Spungen. They’re played by Gary Oldman, in a volcanic career-launching performance, and a devotedly shrill Chloe Webb. With the narrative fulcrum of the Pistols’ final show, in San Francisco in 1978, Cox keeps a close watch on the paramours’ affair, which plays out in scene after scene of paradoxically peppy miserablism. The movie is compassionate and comprehending but detached enough to avoid glorification, and that’s why it still holds up. Cox’s hyperreal style — visually odd but alive and unpretentious — stays true to the spirit of his enterprise, and therefore stays fresh. Any film with fed-up young people against billy-club-swinging cops seems topical now; this one’s instructively timeless. It’s a bracing reminder of how musical movie portraits lately have gone soft on us.