Bookmark Tower

I trotted through the front door and down the sidewalk right into the quiet neighborhood bookshop! Back in the corner reading nook, someone had left a disorderly pile of stiff cardboard bookmarks scattered across an empty shelf. Three had bright yellow ribbons, and three had plain blue edges. I gripped the first thick blue rectangle and set it flat as a solid base. Tap, nudge, balance! Then I crossed two ribboned ones over it like tiny crossbeams. Clack! With steady hands, I built a neat, airy three-tier tower of clean right angles.