HTML

Diagram Design's charts are output in clean HTML and SVG formats, rather than relying on a chart library rendered at runtime.

HTML named entities such as   are not defined in standard XML; a DTD must be declared first or the numeric entity   must be used instead to be valid

The prompt should require the AI to use native HTML, CSS, and JS, because pages generated with native HTML are more lightweight and easier to deploy subsequently.

When multiple SVG fragments are inlined into the same HTML page, identical ids cause naming conflicts; the browser retains only the first definition encountered, and subsequent references to the same name may fail to resolve or fall back to transparent.

These landing pages are built using only native HTML, CSS, and JavaScript, with each page self-contained in a single HTML file, with no frameworks, dependencies, or build steps.

Single-file HTML allows Claude to directly read the implementation itself, including the visual language of typography, color, spacing, layout structure, component styles, and animation interactions.

Markdown supports complex elements such as tables and charts, and can natively embed HTML.

HTML or rich-text formats carry a large number of redundant tags, increasing token consumption and interfering with the model's comprehension of content.

enterkeyhint is an enumerated attribute of HTML input elements used to inform the mobile virtual keyboard of the expected action upon completion of input, thereby replacing the Enter key icon.

Hyperframes chose HTML as its input format because large language models excel at generating structured text and HTML is a common format in training corpora.