Topic-list-previews: Tiles: there's a momentary glitch when new records are rendered

Steps to Reproduce

There’s a brief moment when new tiles are rendered on top of one another but not yet moved into place by masonry. You are not usually at a position in this list to see this, but if quick you can catch it if you scroll back on desktop, for example. This can look a bit ‘glitchy’. Would be good to find a way to either render the tiles off screen initially or somehow switch their CSS so the tiles don’t appear to be stacked in same place initially.