Hi, maybe you found out already.
There are the breakpoints 764 and 990.
The buttons are displayed side by side, while the "statistic button" seems to be a bit wider than the "new question button",
between a screen width of 712px and 764px:
between a screen width of 926px and 990px:
wider than 1586px:
Well, you can use the "lime-admin-colors.css" in "themes/admin/[your admin theme]/css"
Here I entered your desired "div#survey-grid .btn {display:inline;}"
and some colors to show
Here an example screen width 1100px:
Joffm
P.S. Remember to empty the asset cache.