the header, footer, sidebar - are certainly components.
logo, menu, language switcher, social networks, hamburger:
logo - Yes menu - Yes,
the language switch is not required, but if this code block takes a lot of space, you can make a separate component
SOC.network - usually Yes. Because usually social.network where a lot of the site uses,
hamburger - probably not worth it because: 1) is an integral part of the cap, 2) don't take up much space.
If desired, small pieces of the type of Burger you can make a subcomponent, if the build system allows.
So what is a component:
1) independent unit - part code used independently from the parent, can be used in different places
2) big block - big chunk of code that has a specific purpose, the type of banner, slider, etc. Let it never and never more used, except on the main, but he's a big and independent boy. So settle separately.
Here at least two distinctive features of components from componentb.
Oh, I something about marking all said =))
About styles - as said above, all you need to separate. Well, if each css file will contain the layout of only one logical block.
PySy: looking at your screenshot, it seems that the folder for these files is not needed. The point in such long and repetitive ways?! components/header/header.scss Yes no