Whilst playing around with some table formatting in another post I found another nifty trick to target a smaller area which also can be used in this context. Mark the section by some random tag, i.e. #flag, and use CSS as shown below to hide the tag, and to format that section to your hearts content.
a[href="#flag"] {
display: none;
}
div:has(a[href="#flag"]) {
... whatever styling you like ...
}
This way the extra markup is minimal, and the visual impact is hidden in the rendered views, but it still allows you to do whatever you want with the marked section. In the linked thread above, I also show examples of how you can use this to first anchor the CSS to the table, and then continue to style smaller parts of the table afterwards. This trick also works for both live preview and reading mode.