[Ajumma]

For example : https://codepen.io/oknoblich/full/tfjFl and https://codepen.io/villa7/pen/grPddp

For the Accordion, the first item could display the posts. And for the tabs, the first tabs could display a list of postings.
I'm looking for a SUPER SIMPLE wordpress theme and these cute Accordion/Tab menus would make the perfect theme. However, 99% of the themes online are full page themes and they're not this small.

Is it possible to convert these HTML/CSS templates into a full working theme?

Here's a sample of what a mini website could look like :

[VirtualFrost]

Well I mean yeah of course it can, all websites are made up of HTML/CSS, you just need to put it together. You'd just take those templates and then set it up through whatever Blog software you're using. It's not really easy to explain how to obviously put it together, but in short yes you can put anything together as a theme, it's all just HTML/CSS.

[DeepuEzy]

Well, it is indeed possible with Nextend Accordion Menu or similar one's..

[Snow.]

I think you could achieve this by using a simple theme and search for a suitable plugin, which you may alter to your needs, there are plenty of menu plugins.

[Ajumma]

I think you could achieve this by using a simple theme and search for a suitable plugin, which you may alter to your needs, there are plenty of menu plugins.

Thanks. I just stuck with the HTML and coded a mini system for it in PHP. Took a while since my PHP is rusty but it works :)

[DanielN]

You need a header and footer and the WordPress loop code in the middle to have a basic functioning WordPress theme. Any additional elements that are generated from the DB have to be created and added as widgets.