This is Boundless. It is a splash page.

The Boundless splash page is a simple, clean, one-page template by Kat Suricata (whose site is a good live example of it). It is licensed under a Creative Commons Attribution 4.0 International License. It is responsive and made with fully-valid HTML5/CSS3 code. It works well with every modern rendering engine and degrades legibly on older browsers (to a reasonable point). Download the template here.

Examples (slightly outdated):