CSS Web Components for marketing sites

CSS Web Components are a JavaScript-free approach to building marketing site design systems using custom HTML elements styled entirely with CSS. Unlike traditional web components that require Shadow DOM and JavaScript for registration, this pattern wraps standard HTML in custom element tags and uses CSS attribute selectors to implement component variants and functionality. The approach enables progressive enhancement, minimal dependencies, full SSR support, and leverages modern CSS features like cascade layers, container queries, :has(), and CSS variables for theming and conditional styling.