How web developers deal with unexpected long texts in buttons[because of cms source of content]?

They deal with it by adding some padding. (ProudEminem.png)

What pug is and what can provide for me in this task [don’t have to repeat changes in each file if I want to change something in the website layout] (https://github.com/pugjs/pug )

Pug is a kind of extension for HTML that makes our work easier.

We can see how it works in this site (Syntax part): https://github.com/pugjs/pug

I can’t find an answer on 2nd question, but I assume that we can put changes in a few files in one shot.

What ,,entities" are and why are they used like that?

Entities are special marks and they are part of HTML code, so we don’t have to link external fonts, that would slower our website and make it less efficient.

What changes in script loading when you put HTML properties:async, defer, x to script tag?

Async - means execute code when it is downloaded and do not block DOM construction during downloading process.

Defer - means execute code after it’s downloaded and browser finished DOM construction and rendering process.

In synchronous mode, your website’s code scripts will load one after the other. A script can only be loaded if the previous one has finished loading. If a script is blocked, it will block the scripts after it from loading.