needs some updates for ghost version4

[athamour1]

I liked very much this theme, so I tried to make small changes to be compatible with ghost 4, I saw 2 problems the logo of the site above the posts and the images from the posts.
I don't know if the following is right, but for me the following style, it worked.

a#blog-logo {
  display: none!important;
}

figure>img {
  border: 0!important;
  object-fit: contain!important;
  height: auto!important;
}

[sec-fortress]

how do i implement or update this, what file in the zipped file and what line please