Rangers trounced Celtic 3-0 at Ibrox as Michael Beale enjoyed his first win over the Hoops as Gers manager.Midfielder Todd Cantwell fired the home side into the lead after five breathless minutes before returning defender John Souttar headed in his first Light Blues goal from a corner on 34 minutes.Attacker Fashion Sakala made it 3-0 in the 70th minute to clinch a convincing victory over the below-par cinch Premiership champions.It was Beale's first success in five attempts against the Parkhead side since taking over from Giovanni van Bronckhorst last November and it ended Celtic's 34-game unbeaten domestic run - although Ange Postecoglou's side remain on course for a domestic treble, with the Scottish Cup final against Championship side Inverness at Hampden Park to come on 3 June.If nothing else, it was a much-needed marker for Beale and Rangers with a view to next season although they will realise the title and the ViaPlay Cup were already safely in the Celtic Park trophy room.Pre-match speculation about team line-ups ended when it was announced that Souttar was taking over from the injured Ben Davies, Ryan Jack returning to midfield and Rabbi Matondo and Sakala leading the line, with Robby McCrorie again preferred to veteran Allan McGregor in goal.Postecoglou replaced Greg Taylor with Alexandro Bernabei and brought in South Korean striker Oh Hyeon-gyu for Kyogo Furuhashi and winger Liel Abada for Daizen Maeda.There were no away fans in the stadium due to "safety and security" issues, as was the case when Rangers visited the east end of Glasgow in April, and it was a blistering start from the home side which produced the opener.As the Hoops defence gasped for air, midfielder John Lundstram's shot from 25 yards was