Because I was fed up with the lack of options (none), I write a tool that can format Go HTML templates: you can find it here. Includes screenshots!

Formatting Go text templates is pure madness, but the above code works well on HTML templates. If have find issues or need more functionality open a PR against the repo.

Have this in neovim:

au FileType gohtmltmpl command! Fmt silent %!gotmplfmt
au FileType gohtmltmpl let &l:formatprg="gotmplfmt"