First off, it’s important to understand Responsive Design responsive design and why you shouldn’t be writing your own css these days as a newbie. Bootstrap is a public css doc with a lot of those problems pre-solved, so you might want to look up some of their tooling.
As far as a website: you’ll need a domain name, you can get some for free, but they usually have short renewals otherwise this is unavoidable.
You can pay for “shared hosting” at any of the major vendors like blue host or GoDaddy and get apache or aspx file hosting for like you said $X0/year.
You can use an s3 static website for ~free. Creating a DNS hosted zone is $.50. but you can create an s3 bucket (think flash drive in the cloud) store a threshold of free documents, and publish them as a website all within the free tier of AWS. This has some technical background and AWS can get expensive of you make mistakes (although this shouldn’t scale much unless you upload a thousands ton of files repeatedly)
Alternatively you can use GitHub pages . Git is a tool used by developers to share and edit code, they let you publish free HTML as well, but requires learning git or figuring out a tool with a UI like source tree. I don’t think you can use custom domains with this though.
Although if you have any interest in tech, you can also create a free nginx docker container through a lot of services like ecs, but you can also self host in a “sandbox”. Docker creates a mini virtual machine with all of the code required to run self contained. Nginx let’s you create HTML docker containers by mounting a directory. ~ docker start nginx /website/directoryAnd it just runs self contained.