Reland "Reading list: Tweak CSS"

This is a reland of commit 1348f15cbd728f30c3af91bd54f2234ce7126a9d
The problematic change leading to the revert was the change to make
the card shrink to fit non-overflowing contents, vs. remaining at a
consistent height regardless of contents height. I've removed that
from this version of the CL, to address separately.

Original change's description:
> Reading list: Tweak CSS
>
> Small modifications to reading list CSS following up to
> crrev.com/c/6096619
>
> Before: https://screenshot.googleplex.com/5zU8kSXUedenJCm,
> https: //screenshot.googleplex.com/5mEccRCQXe99bjF
> After: https://screenshot.googleplex.com/3gZudetFYTSLdbu,
> https: //screenshot.googleplex.com/35SxRW8X7VcredB
> Bug: 41489841
> Change-Id: Ie60b2d1a9f21597129249d79cbb2caf7e905451e
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6228139
> Auto-Submit: Emily Shack <emshack@chromium.org>
> Commit-Queue: Emily Shack <emshack@chromium.org>
> Reviewed-by: Caroline Rising <corising@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1415737}

Bug: 41489841
Change-Id: Id9bc5fbca46ef9b75cf76a71582faf5876749f67
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6240887
Commit-Queue: Emily Shack <emshack@chromium.org>
Auto-Submit: Emily Shack <emshack@chromium.org>
Reviewed-by: Caroline Rising <corising@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1418348}