The post-framework era

The frontend ecosystem rearranges itself every few years. Your buttons, dialogs, and dropdowns do not need to. The problem is that most component libraries make them, because the primitives are coupled to a framework rather than to the platform underneath it.

This page is the reasoning behind the library. It is not required reading before Installation — but it explains why the markup on every component page looks the way it does.

The cost is transferability, not bundle size

A component library written for one framework is only reusable inside that framework. shadcn/ui is React; using the same primitives in Vue or Svelte meant the community re-implementing them as separate projects rather than importing them. That is the coupling made visible: the design work transferred, the code could not.

So the cost of switching frameworks is not only the application. It is the layer underneath it — the layer that had nothing framework-specific about it in the first place. A dialog needs a top layer, a focus trap, Escape handling, and an accessible name. None of those are React opinions.

Timeless keeps that layer in the two languages every framework already renders: HTML and CSS. A custom element is an HTML tag, so there is no adapter to write and no boundary to cross. The framework guides are about where the imports go, not about a different implementation per framework.

Why this became possible

Frameworks did not invent overlays and dark mode for fun. They shipped those features because the platform had no version of them. Each row below was a genuine gap, and each has since closed:

Once needed framework or library code	Now a platform feature
Positioning a surface next to its trigger	CSS anchor positioning
Top layer, light dismiss, Escape, focus trapping	Popover API and <dialog>
Dark mode through a theme provider and a class	light-dark() and color-scheme
Winning a specificity fight with library CSS	Cascade layers
Component state a stylesheet can read	ElementInternals states and :state()
A click handler to open a dialog	Invoker Commands (command/commandfor)
A reusable tag that carries its own behavior	Custom elements

These were not framework ideas. They were framework workarounds, and a workaround outlives its reason quietly. The exact versions each feature landed in, and what happens in a browser missing one, are in Browser support.

How the library uses that

There are 49 documented components, and they divide by whether the platform can express them declaratively.

26 are CSS over native HTML, with no JavaScript at all. A class on real markup. There is no runtime to boot and no hydration step, because there is nothing to hydrate — it is a stylesheet.

23 are custom elements, used where keyboard coordination, focus management, or ARIA relationships genuinely cannot be expressed in CSS. Those elements enhance markup you already wrote; they do not render it. Popover is the pattern all of them follow:

<ui-popover>
  <button type="button" data-ui-part="trigger" popovertarget="menu">Menu</button>
  <div id="menu" popover="auto">The content</div>
</ui-popover>

That opens, closes, light-dismisses, and handles Escape with JavaScript disabled, because popovertarget and popover are platform attributes. Registration then adds only what the platform does not: aria-controls, aria-expanded, a default aria-haspopup, a surface role, and anchored positioning. Nothing is created, so nothing can arrive late and rearrange the page.

The markup you author is the markup that ships. That is what removes the unstyled flash and the shell that shifts once a bundle lands — there was never a moment when the DOM was wrong.

Two components have no declarative shell

Context Menu needs pointer coordinates and Copy Button needs the clipboard. The platform offers no markup for either, so both require JavaScript to do anything. Each says so on its own page rather than leaving it to be discovered.

What is different from the other framework-agnostic libraries

Framework-agnostic UI is not a new idea, and pretending otherwise would be dishonest — open-wc keeps a list of component libraries built on the same standards. Several are excellent. Timeless makes three different trades.

CSS-first rather than JavaScript-first. In most web-component libraries the component renders from JavaScript, so the element is empty until its bundle executes. Here more than half the library has no JavaScript to execute, and the rest enhances existing markup instead of producing it.

Light DOM rather than Shadow DOM. Shadow DOM gives real style encapsulation, which is a legitimate thing to want. It also means your stylesheet cannot reach inside, so styling happens through whatever custom properties and ::part() hooks the author remembered to expose. Timeless keeps anatomy in the Light DOM as a data-ui-part token list, so your CSS — or your utility classes — select it directly. Cascade layers put your rules above ours without a specificity fight.

Server-rendered output that is already correct. Declarative Shadow DOM has made SSR workable for shadow-based libraries, so this is a narrowing gap rather than an absent capability. The distinction that remains is what the first paint is worth: Timeless emits plain HTML and CSS that is styled and operable before any script runs, rather than markup awaiting an upgrade.

The trade is deliberate. You give up style encapsulation, and you get markup you can inspect, override, and server-render with no framework in the request path.

What post-framework does not mean

It does not mean less rigor. It means the rigor moves out of a runtime and into the build.

Nothing here re-implements what the browser already does, so the discipline is in keeping the boundaries honest. Every public attribute, part, state, and permitted value is declared once in a component registry, and the build proves those values against the stylesheets in both directions — a documented value is a value the CSS implements. The CSS ships in three tiers, and a script fails the build if a core/ stylesheet declares a colour or a theme stylesheet keeps a property core owns. Styling covers what that split means when you replace the theme.

You still own accessibility, and so do we: the conformance target is WCAG 2.2 Level AA, every interactive component declares its keyboard contract, and the end-to-end suite asserts each component still reads correctly with the theme removed.

Frameworks were a loan taken against an unfinished platform. The platform shipped. This is what it looks like to stop making payments — not less engineering, just less of it spent in your users’ browsers.

Next

• Installation — add the package, load the CSS, register an element.
• Quick start — build an interface from native HTML and explicit enhancement.
• What Timeless does not ship — where the boundary of “primitive” sits, per component.