Everyone is building Web Components now - why? They are cool but what you are doing is sticking a knife into javascript and sewing in a new kidney. The only relevant purpose is when you have to have a custom add-on to JS and don't mind the latency burden.

What about other components? Now we're splitting hairs. Nope, it is wise to build up a collection of webpage components that perform standard functions like navbars, cards, modals, galleries, etc. Even footers and headers can be built on the side to optimize construction of a new website.

One of the most tedious elements is the navbar. When you want a fixed, semi-transparent, match page to tab, burger, close on click... navbar, there is a lot of CSS/JS to write and who can remember how to do it? Just build a template component and set it aside in your web-kit toolbox. Other features we tend to forget is parallax image effects, smooth scroll with background color changes, custom animations to avoid massive add-on libraries, etc.

Grid and Flex are a must. Having templates of various features like galleries, layout controls, grid fields, responsive column and row @media statements is going to save you a lot of time and frustration.

So how do you go about all this? The best way is to dedicate a directory to webpage templates and components. Maybe call it 'Web_Kit_Archive.' Use sub-directories to find things fast like galleries, modals, cards, img-considerations, global-CSS-defaults, responsive-mobile-first, etc. Go ahead and build sample complete websites that feature different approaches. When the time comes to build a new site having a jumping off point will also be very motivating. Avoid the stress and get started while avoiding to learn a new library or framework. In the end, those things change and go out of date. Standard CSS/JS is much more stable.