You can write whole website in just single web page.

I'm using :target for creating this repo

CSS

section {
  display: none;
}

section:target {
  display: block;
}

HTML

<a href="#home">Home</a>
<a href="#about">About</a>

<section id="home">
You can create whole website just in single page.
</section>

<section id="about">
This is my tiny project. I'm love create code. I'm intersting for making code, program, websites.
</section>

Every time you click on those links #home, #about.
Adding on your current URL.
:target is responding on any # value. You see section:target all section visible.

Comments

[Ravavyr]

Yes, but this is

• Terrible for SEO [More pages is better, each one with custom urls]
• Terrible for performance, If you have a 10 page site with images, you'd be loading all of it at once.

Still a neat trick though :)
The "target" bit might be useful in other situations, for example for "tab" navigation within content.

[Gaurav Singh]

This idea may be best suitable for small, concise portfolio website.