In the themes' layout configuration screen, is there a way to define layout block's width as "flexible", instead of a set percentage width?

What I want to achieve is to add a menu to the left of "search-login" module in the nav bar, as shown in the first picture(In the picture there is only 1 button with pencil icon, but there are more to added). Problem is, if the search-login has a set percentage width, then this menu won't be right next to it on all devices. So is there a way to make search-login module position only as wide as its actual content?

P.S. I've tried another way to achieve what I want: I've tried to modify the search-login particle by adding a position to hold the menu module, but a menu module can't show icon-only menu items(to show icon-only menu item, it has to be in a menu particle), so I have to hardcode a link to the menu item into the search-login particle, but if there are multiple menu items in the menu that I want to add, it doesn't feel right.