Struggle with several elements

Hello,

I have several problems on my site that I can’t solve:

Enlarge the navbar so that I can insert some text and it cuts into the image part.

The black button at the top: I can’t change its color when I hoover on it.

The slider images: I can’t change the 3rd image. Also, I can’t add an opaque background to allow a better readability of the image.

The text on the left below the logo: it is always underline, I do not understand why and I would like to remove it.

best regards

https://preview.webflow.com/preview/yacines-sublime-site?utm_medium=preview_link&utm_source=designer&utm_content=yacines-sublime-site&preview=d2f416c1106e983ea3722580c6076d9c&pageId=6386aabb745e453b27c1068c&workflow=preview