Themes and tag HTML

I’m creating a theme, how can I style a tag or ID in my file yaml?

Example: for the <hui-vertical-stack-card> tag I would like to set a background color and a border-right.

Example: for a <div id="xxx"> I would like to set a font-size style

hi,
for example

Hi, I know and use card-mod, but I would like to integrate the style at the template.yaml level