Skill specializations

So, I'm building out a custom character sheet for my homebrew system and it allows for skill specializations. Right now I'm using a repeating section for the skills which will work fine for just base skill fields. However, I'm drawing a blank on how to add in something to signify that a skill would nest as a specialization under a main skill. Any ideas would be helpful because I'm just not even sure how to get this done with only HTML.

If you mean you have a repeating section of skills, and a skill can have an unknown number of specializations, then you can't nest repeating sections like that. One option might be to have a repeating section of skills, and a second repeating section of specializations, with each specialization giving you a space to note which skill it's for.