Filling/Caulking Big Gap on Stair Riser

I recently replaced my carpeted stairs with new hardwood treads. They look great, except that on one side, it's obvious the home installed the side trim a little off - on about 4 steps there's a gap where the stair, riser, & trim meet. The biggest is about a 1/4 inch. I was going to tape off, put a tiny amount of gap filler, cut, then caulk over. But I'd be interested to hear anyone else's recommendations for the cleanest way to fill these gaps. Attachment 50103 (http://www.doityourself.com/forum/attachments/carpentry-cabinetry-interior-woodworking/50103-filling-caulking-big-gap-stair-riser-fullsizerender.jpg)