WebToolArcBrowser-local does not mean standards-complete
HTML parsing is error tolerant. Source diagnostics, sandboxed previews, and transformations do not replace full conformance, security, or production-browser testing.
The parsed DOM can differ from the source string
An HTML parser repairs and normalizes markup while building the document tree. It can insert implied elements, close tags according to the parsing algorithm, move nodes into valid locations, decode entities, and normalize attribute handling. The resulting DOM tree therefore answers “what structure does the browser parse?” rather than “what exact bytes were typed?”
Use source and DOM views for different questions
Inspect the DOM when debugging selectors, nesting, accessibility relationships, or browser interpretation. Inspect the original source when whitespace, quoting, serialization, template syntax, or malformed markup itself matters. A structurally reasonable DOM does not prove HTML conformance or security; use a standards validator and context-appropriate sanitization when correctness or untrusted content is important.