I think today, you can use Racket in its special SICP mode to get a much better experience. But maybe the HTML (Bootstrap) formatting is a little nicer to read (and with the bonus that it probably works on phones).
The interpreter was incomplete and written from scratch, as a learning project [2]. This was done in the pre-WebAssembly days, so I couldn't just recompile, say, a Scheme written in C for use in the browser.
If I recall correctly, I took the SICP source files, ran a bunch of regular expressions on them to convert the content into XML [3], and then used XSLT to generate the web pages [1]. I was really into XSLT at the time :)
Anyway, hope people find this useful! It's outdated and incomplete, and the interpreter has an odd implementation, but it was a fun project.
Source code links:
[1] HTML generator: https://github.com/jaredkrinke/learn-scheme
[2] Interpreter: https://github.com/jaredkrinke/jslisp
[3] SICP-to-XML converter: https://github.com/jaredkrinke/sicp-reformatter