Function browser_host_html_themed 

pub fn browser_host_html_themed(
    name: &str,
    declared: Option<&str>,
    favicon: Option<&str>,
    theme: ShellTheme,
) -> String

The HTML shell that loads a LOGOS→WASM DOM app, with a page’s own Head: merged over the defaults.

The one merge every document builder reads — largo build’s pre-render, largo serve’s dev response and largo emit — so development and production serve the same document. favicon is the SITE’s own icon when it ships one (static/favicon.svg), which stands in for the built-in clay-λ data URI as the DEFAULT — so a page that declares its own <link rel="icon"> still wins over both. theme is whether the built-in theme comes with it.