The first real chance of the game came Stockport’s way on 25 minutes, when Kyle Wootton’s flick-on played through Andresson, whose shot beat Trott but came off the foot of the post and bounced to safety.
The hosts should have been ahead seven minutes later, when Ben Osborne’s cross found Andresson between the two Cardiff centre-backs, but his header was straight at Trott, who still had to make an excellent reflex save.
A minute later the hosts were awarded a penalty, as Ng got the wrong side of Andresson and bundled the Stockport striker to the ground.
Up stepped Norwood to score his third goal of the season, as Stockport took a deserved lead.
The lead should have been doubled when Ryan Wintle was dispossessed and Wootton found Andresson inside the Cardiff box, but Will Fish got back to make a crucial deflection.
And the onslaught continued from the resulting corner as Joseph Olowu was left unmarked eight yards out, but he could not keep his volley down and Cardiff escaped again.
The second half started as the first ended, with Stockport committing numbers forward and working their way into the Cardiff box, this time Jack Diamond denied by Trott.
Cardiff thought they had found an equaliser against the run of play when Chris Willock’s low cross was poked home by Salech, but the flag had already gone up for offside against Willock.
And as Stockport took their foot off the gas in the seven minutes of added time, Salech’s late header stole a point for the league leaders.