You can start by using plain, semantic HTML and grabbing a classless CSS with a license you like. (Check out this list.)
It's good enough for a simple app or site, and it's honestly impressive how good something can look with just this. It's the "plain t-shirt and jeans" of web design.
We do have CI (Azure DevOps), we aren't that insane. Though to be fair, it's relatively recent. The legacy app has a build pipeline but no tests. We got automated deployments to lower environments set up about a year back.
My main project has build pipelines as well, Spring Boot "microservices" (probably a red flag given our size and infrastructure) with code coverage around 40-60% mostly unit tests. But I'm the only dev that really writes tests these days. No deployment pipelines there though as the SysAdmin is against it (and only really let us do the legacy app reluctantly).