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no DOCTYPE (quirks) · meta charset=Shift_JIS

(19) Legacy charset + quirks mode — harmless (verify)

Reproduces the worst legacy-HTML combo found live (Tokiwa-dai Shift_JIS, spacejam quirks). Hypothesis to verify: the widget boots normally because (1) the external si.js is decoded by its own UTF-8 HTTP header regardless of this page's Shift_JIS, and (2) quirks mode only affects the CSS box model, not Shadow DOM / fetch / ES2018.

Quirks mode probe

document.compatMode should report BackCompat (quirks) here because the DOCTYPE is intentionally omitted. The widget must still boot — observe the panel below.

Low-contrast text (control sample for contrast feature).

Charset note

This page declares charset=Shift_JIS. Per the report, that is the only harmless legacy trait: the browser has already decoded the DOM to Unicode, and the widget's injected Japanese UI text lives in JS UTF-16 strings — unaffected by host charset. (File body kept ASCII to stay safe when saved as UTF-8.)