Popup broken in Chrome with some locales (Italian)

[ghostwords]

If I open the popup using messages from the Italian locale in Chrome (version 66), I see constant jumping but no content on pages with third-party domains to display in the popup. This may be a Chrome-specific bug.

git bisect led me to 5a8d934 as the originating commit for this problem. Looks like changing min-width on body from 400 to 430 pixels did it.

What is it about our CSS that a width tweak can completely break rendering in some situations (longer locale strings? not clear yet what it is about the Italian locale).

[ghostwords]

It seems that the relevant message is popup_instructions. Both adding and subtracting characters seems to avoid the problem, so it's something about this particular message's exact length (and word spacing?).

English:
potential <a target='_blank' title='i18n_what_is_a_tracker' class='tooltip' href='https://www.eff.org/privacybadger#faq-What-is-a-third-party-tracker?'>trackers</a> on this page. These sliders let you control how Privacy Badger handles each one. You shouldn't need to adjust the sliders unless something is broken.

Italian:
potenziali <a target='_blank' title='i18n_what_is_a_tracker' class='tooltip' href='https://www.eff.org/privacybadger#faq-What-is-a-third-party-tracker?'>tracker</a> in questa pagina. Con questi pulsanti puoi controllare come Privacy Badger tratta ogni tracker. Non dovresti averne bisogno a meno che qualcosa non funzioni correttamente.

[ghostwords]

It seems this Chrome bug has to do with the scrollbar. If popup_instructions is just the right length, Chrome seems to get confused and proceeds to continuously alternate between rendering the popup with and without a scrollbar.

[ghostwords]

This is related to #1077 / #1113.

[ghostwords]

From a CWS review:

su firefox nessun problema, su chrome in alcuni siti, quando clicco l'icona di PB, l'immagine vibra in modo insopportabile.

[ghostwords]

Filed crbug.com/838150.

[ghostwords]

Seems that changing body padding in bc231ec triggered this Chrome bug in the Italian locale. (5a8d934 is a followup commit that adjusts the width to account for border-box sizing; commits inbetween don't exhibit this issue because of greater body width.)