I've just tried to use <h7> and it's not recognized. It's the first time I've needed to use more than 6 headings. Does anyone know if there are only a limited number you can use or am I missing something?
Thanks

If you need more than 6 headings, you're probably using them incorrectly.

h1 is for the top most heading (site name, etc)
h2 is for a subsection of the site (about me, navigation, etc)
h3 is for a subsection of the h2
h4 is for a subsection of the h3
h5 is for a subsection of h4
h6 is for a subsection of h5

If you are down to using h6 and you're out of headings, you should think about restructuring your page.