Screenshots
MediaWiki:
![image](https://user-images.githubusercontent.com/8334194/196055660-e5a59c48-7cb6-4099-b189-ffa6d658396b.png)
Site before:
![image](https://user-images.githubusercontent.com/8334194/196055665-755ddcbb-769c-4086-9fb4-6b4ad6301d07.png)
Site after:
![image](https://user-images.githubusercontent.com/8334194/196055669-516e6f76-f5cd-4437-89aa-89eb38955f02.png)
Tested using Firefox's style editor and inspect element to replace the text. Based on this and this from the MediaWiki vector skin.
This fixes h3 being bigger than h2, which was particularly obvious on the Wii Network Guide page.
Screenshots
MediaWiki: ![image](https://user-images.githubusercontent.com/8334194/196055660-e5a59c48-7cb6-4099-b189-ffa6d658396b.png) Site before: ![image](https://user-images.githubusercontent.com/8334194/196055665-755ddcbb-769c-4086-9fb4-6b4ad6301d07.png) Site after: ![image](https://user-images.githubusercontent.com/8334194/196055669-516e6f76-f5cd-4437-89aa-89eb38955f02.png)Tested using Firefox's style editor and inspect element to replace the text. Based on this and this from the MediaWiki vector skin.