Hello!

Since when does the bug occur?

I recently upgraded my mkdocs package from 1.4.2 to 1.5.2, and I noticed this bug when...

• I don't specify a page title in mkdocs.yml file or in the page metadata (in yaml).
• I use an emoji (HTML in general) in the first level section title in the markdown file:

# Intégration et Déploiement Continu sur :simple-gitlab: Gitlab

For example (with mkdocs-material theme and readthedocs theme):

... while it was displayed like that before:

More generally, some parts like the search page of readthedocs theme don't handle well the HTML in title sections.

External links:

readthedocs theme pictures and bug explanations are from @squidfunk.