Excerpts runs off the side when using excerpts + thumbnails

[debryc (Deborah Chang)]

Found something! On mobile the text runs a little off the side when paired with topic preview.

This is an iPhone running the latest version of iOS.

[Canapin (Coin-coin le Canapin)]

I can repro it:

In topic-list-thumbnails, default thumbnail mode must be set to list for the bug to happen.