You can absolutely apply CSS to a single tag. I recently did the same looking to capitalize a letter in a tag.
In short, you can handle most cases with the following (replace tag_name_here with the tag you wish to style):
.tag-tag_name_here {
// Declarations go here
}
Depending on the exact style you want, you may need more rules to handle all cases. You can see the final set of rules we came up with for my issue here.