Kind of complicated, but do-able.
Use your Simple CSS plugin: https://wordpress.org/plugins/simple-css/
This will give you a CSS metabox on that page which you can add CSS to that will only apply to that page.
Then do something like this:
.separate-containers .inside-article {
background-color: transparent;
padding: 0;
}
Then you’ll need to wrap your content in the containers you need to have like this:
<div class="my-cool-box">
Some content
</div>
<div class="my-cool-box">
Some content
</div>
Then you can add this CSS:
.my-cool-box {
background-color: #FFFFFF;
padding: 40px;
margin-bottom: 20px;
}
That should get you on your way π