Hello,

Regarding making responsive slider for mobile view, please add following given CSS code in Additional CSS section by going to Admin Panel > Appearance > Customize > Additional CSS

@media screen and (max-width: 594px){
  #featured-slider article {
   background-size: contain;
   background-position: inherit;
   background-repeat: no-repeat;
  }
}

Also, regarding post title and excerpt, we are not quite clear wit the query as post title and excerpt are displaying properly under post image in mobile view as you can see in screen shot below.

https://prnt.sc/td8xat

If it is not what you meant then please explain in detail with specific screenshot of the section you are referring to.

If you have any queries further, let us know.

Thank you.