I would like to know if it is or not a good practice to put the introduction paragraph of every page of my website on a header. The content of my page, will directly start on the header, which is a dark picture. The text will be in white to be readable.
So the introduction of my page is in the header, do you think
Aside from users' F-shaped reading pattern, there's no reason that such a design would be inherently bad, in and of itself.
What isn't necessarily a good practice, though, is designing the templates for the pages before you know what the content will be. Content-first design will help your site's design reinforce the content, rather than forcing you into a position where you need to adapt the content to fit the design. (Users don't necessarily care about your design, per se...they are at your site for a different reason—one that your content can help them with, ideally.)
As Nate mentioned, there is no reason this design might be bad. However, I feel headers usually are included on webpages (or even documents) is to have some consistent information on every page.
With that said, why not inlcude the intro in the main section of the page. I would like to understand, why you are considering the option of including it in the header?
