[FEAT] Improve the `blog` and `news` pages

[tbouffard]

Is your feature request related to a problem? Please describe.
Integrate feedback collected during developments

Manage feedback

• Check feedback about the 'more' button: [FEAT] Don't display all the posts in the 'Blog' section of the 'Home' page #225 (comment)
• Check other feedback: [FEAT] Don't display all the posts in the 'Blog' section of the 'Home' page #225 (comment)
• "blog posts" page: The fade effects sometimes hide the posts on the latest line (especially with 9 elements, when reaching the bottom of the page), let's check if we can do something about it
• Ensure navigation from/to home and news/blog page is ok. In particular, when clicking on the logo, we should go to the top of the home age. We often go to the previous position in the home page
• Have a Back button on the top left in the News and Blog pages
• Check that the navbar in the blog and news page is displayed correctly on mobile in particular, no white text on white background (this can occur depending on the form of the red and blue triangles)