Change logo img just on homepage

Site URL: https://www.andrewmarston.com

I'm trying to change the logo image just on the homepage.

I enter the code below into the advanced page settings but it doesn't change the image, only displaying the code at the top of the page (see attached screenshot).

#collection-5e555c3449a12573884f3abf .header-title-logo img {
    content: url(https://static1.squarespace.com/static/5e5550e…/5e5945f…/5e62fb1…/1583544754043/Logo2020-white.png);
}

wrap your code in style tag

<style>
  paste your code here
</style>

The reason for this is that Page Header Code Injection is injected into the HEAD of the document, rather than the BODY. So, when you use custom CSS in this way, it must be contained in a style tag so when it's injected into the HEAD, it has the proper format.