As per many other comments, it sounds like a static site generator like Hugo (https://gohugo.io/) or Jekyll (https://jekyllrb.com/), hosted on GitHub Pages (https://pages.github.com/) or GitLab Pages (https://about.gitlab.com/stages-devops-lifecycle/pages/), would be a good match. If you set up GitHub Actions or GitLab CI/CD to do the build and deploy (see e.g. https://gohugo.io/hosting-and-deployment/hosting-on-github/), your normal workflow will simply be to edit your markdown and do a git add/commit/push to make your changes live. There are a number of pre-built themes (e.g. https://themes.gohugo.io/) you can use, and these are relatively straightforward to tweak to your requirements. In theory, since the content (markdown) is separate from the presentation (theme), you can change design relatively easily (although in practice there's often theme specific config).