Fix styles in Download tab of charts in "All our interactive charts on" block

[mlbrgl]

Issue reported by @CGiattino

Description

Expected behaviour

Check hover behaviour too.

Steps to reproduce

Steps to reproduce the behavior:

1. Go to https://ourworldindata.org/world-population-growth
2. Open the "All our interactive charts on..." block at the top of the page

Context

Might be superseded by #1447 if we decide to retire the current block (#1380)