Markdown + Preact
This page utilizes the fact that HTML can be embedded in Markdown. Using a CDN, it takes around 4.7KB to download Preact, a very small cost. Of course, this means I am not going to have any advanced libraries available.
What can I do with this? Well, probably some interactive pages. I have also considered Vue.js, but it consumes 40 KB (with capability to use templates). For an absolute minimal site like this, Preact is the better choice.
Demo
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