This might be a poor question for this exchange but is it worth styling for zoomed out browsers? For instance, I can zoom chrome out to 25% and my navigation breaks, should I accommodate for this or will 99% of cases be fine without the extra effort in styling? What case would I run into problems like that?
25%? I wouldn't worry about it unless you have a use case for your page where your users will be that far out.
Now, 75%-125%, you might consider it. Usually your page will work fine at other zoom levels. If it doesn't, it's likely because you have hard-coded something you shouldn't have. (For instance, you might assume that text on a certain line will never wrap. That isn't a good assumption. Different devices use different fonts, which could cause text to wrap in some cases.) In those cases, make sure to only set the sizes to specific values when needed. Let the page flow as much as possible.