This example demonstrates the fundamental building blocks of web-based visualization by displaying a static text message, "Hello HTML!", centered on the page using CSS. The code defines a `.message` class with a font-size of 13 em and text-align center, applied to a div element within the HTML body. No JavaScript is used; the styling is entirely handled through the embedded `<style>` block. It serves as a minimal illustration of how HTML structure and CSS presentation combine to create a basic visual output.