Function render_html 

pub fn render_html(summary: &ConformanceSummary) -> String

Mirrors report.py::_render_html / conformance.html.j2. Hand-translated the same way html_output.rs translates author.html.j2/reviewer.html.j2: the source template has no trim_blocks/lstrip_blocks, so the whitespace surrounding every {% %} tag lands in the output verbatim. The exact shapes below were derived by rendering the real Jinja2 template (both branches of every {% if %}, empty and non-empty loops) and diffing against this string, not by re-deriving Jinja2’s whitespace rules from scratch — trust the literal layout over intuition when touching it.