Improve the CSS of the new download page
_Originally created by @sajolida on [#14921 (Redmine)](https://public-redmine-archive.tails.boum.org/code/issues/14921)_
- Text on top of \[X\] button in OpenPGP toogle, see https://gitlab.tails.boum.org/tails/tails/-/issues/14630#note_36759.
- When I installed the extension, the “Verify” button becomes visible.
But IMO one can easily miss this modification. Would it be possible
to make it more visible? Either by using another colour or by making
this button bigger or animate the background colour or something
similar?
Feature Branch: web/14921-download-css
### Attachments
* [chrome_win1.png](https://redmine.tails.boum.org/code/attachments/download/1823/chrome_win1.png)
* [chrome_win2.png](https://redmine.tails.boum.org/code/attachments/download/1824/chrome_win2.png)
* [firefox_win1.png](https://redmine.tails.boum.org/code/attachments/download/1825/firefox_win1.png)
* [firefox_win2.png](https://redmine.tails.boum.org/code/attachments/download/1826/firefox_win2.png)
* [openpgp_dialog_X.png](https://redmine.tails.boum.org/code/attachments/download/1827/openpgp_dialog_X.png)
Parent Task: tails/tails#12328
### Related issues
- **Related to** tails/tails#10909
issue