How does one go about setting a different logo replacement image for individual post pages?

Help Customization
2

So if I understand this, you want the individual post page logo to be different than the main page logo?

Just as you intuited, this is actually pretty simple to do. All you need to do is change the following
CSS property with the logo you want for blog titles:

background-image: url(https://i.snap.as/one-photo.png);

And all you have to do is add that to the CSS that affects the blog titles on the individual pages and you’ll be golden. Here’s an example of this in action using the code for the initial Add a logo to your blog title solution.

/* This is for the logo of the main page */

#blog-title a {
    background-image: url(https://i.snap.as/one-photo.png);
    background-position: center;
    background-repeat: no-repeat;
    color: rgba(0,0,0,0);
    display: inline-block;
    width: 200px;
    height: 50px;
    background-size: 200px 50px;
}

/* This is for the logo on the individual posts */

#post #blog-title a, #subpage #blog-title a {
    /* Change the logo url */
    background-image: url(https://i.snap.as/another-photo.png);
    width: 100px;
    height: 36px;
    background-size: 100px 25px;
}

Now you’ll probably have to change the width and height to make it work for your image, but the solution should do the trick.

Let me know if that helps in any way — if not, we’ll think of something!