I have a post on my WordPress site (I’m admin) that has H1, H2, and H3 tags.

I want my H3 tags for this post to more resemble my h4 tags in size. However, I don’t want to break the hierarchy and just skip h3 tags and go from h2 to h4. I also only want to do this on this page, so I don’t know that editing the theme is the way to go.

How can I achieve this? Do I just define the size of the h3 tag every time I use it in this post? Could I go into the theme and create a special h3 tag that I can use when I run into this?