vitre-css

v1.6.0

Published

13 days ago

Class-free and style-free web with a high-end glass finish for semantic HTML, plus optional behavior helpers.

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css classless class-free styleless style-free semantic-html stylesheet theme dark-mode vitre vitre-ui ui alerts

Vitre UI

The transparent style layer. Class-free, style-free web with a high-end finish. Clear. Light. Vitre.

A great looking web page without class="..." or style="..." on your HTML elements.

Just add <link rel="stylesheet" href="vitre.css"> (or equivalent) and you're done.

Vitre is single-file CSS for making raw semantic HTML look polished by default. It honors semantic tags without polluting markup, so ordinary elements such as headings, links, buttons, forms, tables, code blocks, dialogs, and details receive modern light and dark theme styling without required classes.

An optional companion file, vitre.js, adds class-free behavior to the same semantic markup — dismissible alerts, a theme toggle, SPA navigation, and focusable splitters. It is entirely opt-in: the stylesheet works on its own and needs no JavaScript.

Install

Use the file directly:

<link rel="stylesheet" href="vitre.css">

Install from npm:

npm install vitre-css

Use a CDN:

<link rel="stylesheet" href="https://unpkg.com/vitre-css/vitre-base.css">
<link rel="stylesheet" href="https://unpkg.com/vitre-css/vitre.css">

Add the optional behavior helpers only if you want them:

<link rel="stylesheet" href="https://unpkg.com/vitre-css/vitre-base.css">
<link rel="stylesheet" href="https://unpkg.com/vitre-css/vitre.css">
<script type="module" src="https://unpkg.com/vitre-css/vitre.js"></script>

For CDN usage, prefer the unversioned unpkg URLs. They resolve to the latest published npm version quickly while keeping copy/paste usage simple. vitre-base.css is optional; include it before vitre.css when you want Vitre's first-paint background, typography, theme, and page-width baseline to apply immediately.

Or import the ESM API from a bundler:

import { Vitre, apply } from "vitre-css/vitre.js";

Documentation

Read the documentation and examples. A complete list of CSS custom properties is in REFERENCE.md.

Usage

Write semantic HTML and let Vitre style the elements directly:

<main>
  <section>
    <h1>Account settings</h1>
    <p>Manage your profile and notification preferences.</p>

    <form>
      <label>
        Email
        <input type="email" placeholder="[email protected]">
      </label>

      <button>Save changes</button>
    </form>
  </section>
</main>

Themes

Vitre follows the user's operating system preference by default with prefers-color-scheme. You can force a theme with data-theme on the root element:

<html data-theme="dark">

Supported values are light and dark.

Customization

The main customization API is CSS variables. Add your own stylesheet after Vitre and override --vitre-* values there:

<link rel="stylesheet" href="vitre.css">
<link rel="stylesheet" href="custom.css">

In custom.css, start with variable overrides:

:root {
  --vitre-hue: 168;
  --vitre-primary: hsl(var(--vitre-hue) 76% 42%);
  --vitre-font-weight: 400;
  --vitre-radius: 0.5rem;
  --vitre-measure: 80ch;
  --vitre-button-height: 40px;
  --vitre-button-bg-angle: 180deg;
}

Useful tokens include colors, spacing, typography, surfaces, borders, focus rings, forms, tables, shadows, and code blocks. See REFERENCE.md for the full variable surface.

Buttons expose background and hover variables. Use data-variant for common button treatments:

:root {
  --vitre-button-bg-image: none;
}

For a single flat button, use the variant attribute instead of adding a class:

<button type="button" data-variant="flat">Flat button</button>

Other supported variants are outline, ghost, and plain:

<button type="button" data-variant="outline">Outline button</button>
<button type="button" data-variant="ghost">Ghost button</button>
<button type="button" data-variant="plain">Plain button</button>

Use data-color for semantic button intent. Supported values are primary, info, success, warning, and error; each variant decides whether that color is used as a fill, foreground, border, or hover tint:

<button type="button" data-color="success">Save</button>
<button type="button" data-color="error" data-variant="outline">Delete</button>
<button type="button" data-color="info" data-variant="ghost">Details</button>

The same data-color values are also supported on progress and meter:

<progress data-color="success" max="100" value="72">72%</progress>
<meter data-color="warning" min="0" max="100" value="68">68</meter>

Resizable panes can mark their drag handle as a semantic splitter:

<div data-kind="splitter" role="separator" aria-orientation="vertical"></div>

Include vitre.js to ensure splitter handles receive keyboard focus and orientation metadata.

Iframes are responsive by default with a 16 / 9 aspect ratio. Use data-fit="contain" on embedded or framed media that should opt into the same stable responsive ratio:

<iframe data-fit="contain" src="https://www.youtube.com/embed/..."></iframe>

Token swatches can use data-token:

<mark data-token="primary"></mark>
<mark data-token="surface"></mark>

If a selector does not expose the exact customization you need, override the element rule in your stylesheet after Vitre:

button {
  text-transform: none;
}

Prefer variables when they exist. If you find yourself repeatedly overriding the same kind of rule, that is a good sign Vitre should expose another --vitre-* variable for that customization.

What It Styles

Page layout primitives: body, header, main, section, article, aside, footer, and nav
Typography: headings, paragraphs, links, lists, blockquotes, mark, small, and horizontal rules
Code: code, pre, kbd, and samp
Forms: labels, buttons, inputs, textareas, selects, fieldsets, checkboxes, radios, ranges, and color inputs
Data and disclosure: tables, details, summary, dialog, progress, and meter
Data patterns: [data-kind="alert"], [data-kind="tabs"], [data-kind="splitter"], [data-color="warning"], [data-variant="outline"], [role="dialog"], and grouped form controls
Media: images, videos, SVGs, canvas, and iframes

Optional JavaScript

vitre.js is a separate, optional file. The stylesheet is fully functional without it — load it only when you want the behaviors below. It ships no component skinning of its own; the styling comes from vitre.css.

<script type="module" src="https://unpkg.com/vitre-css/vitre.js"></script>

Components are selected by the same data-kind attributes the stylesheet uses, so there is no separate markup to learn.

Alerts

Semantic alert markup:

<div data-kind="alert" data-color="success" role="status" dismiss timeout="6">
  Saved successfully.
</div>

Alerts are selected with data-kind="alert". Use named data-color values such as primary, info, success, warning, and error for styling. Add role="alert" or role="status" only when live-region behavior is intended. Add dismiss for a close button and timeout for automatic dismissal, in seconds. Dismiss controls are generated as right-aligned SVG icon buttons with data-variant="ghost". Dismissing an alert emits a vitre:dismiss event.

Theme Toggle

Use a span with data-kind="theme-toggle" to render a light/dark toggle button:

<span data-kind="theme-toggle"></span>

The generated button toggles data-theme="light" and data-theme="dark" on the root <html> element and stores the selected theme in local storage.

Navigation

Use data-kind="nav" on a semantic navigation region to add class-free SPA navigation behavior:

<nav data-kind="nav" aria-label="Primary navigation">
  <a href="/">Home</a>
  <a href="/videos">Videos</a>
</nav>

Vitre intercepts same-origin primary clicks, updates browser history, dispatches a popstate event for routers that listen to history changes, and maintains aria-current="page" on the current link. External links, downloads, modified clicks, and links with target other than _self use normal browser behavior.

Each intercepted link emits a cancelable vitre:navigate event from the clicked anchor. Applications can call event.preventDefault() to hand navigation to a framework router while still using semantic anchors.

Splitters

Use data-kind="splitter" with role="separator" for resizable pane handles:

<div data-kind="splitter" role="separator" aria-orientation="vertical"></div>

Vitre ensures the handle is focusable and has a default aria-orientation when one is not provided. Applications still own the pane sizing behavior.

Tabs

Use data-kind="tabs" around a role="tablist" and its role="tabpanel" sections:

<div data-kind="tabs">
  <div role="tablist" aria-label="Account settings">
    <button role="tab">Profile</button>
    <button role="tab">Notifications</button>
  </div>

  <section role="tabpanel">
    <h3>Profile</h3>
    <p>Profile settings.</p>
  </section>

  <section role="tabpanel">
    <h3>Notifications</h3>
    <p>Notification settings.</p>
  </section>
</div>

Tabs are paired with panels in document order, or explicitly with aria-controls when the order differs. Vitre generates the missing id, aria-controls, aria-labelledby, and aria-selected attributes, manages a roving tabindex, and supports arrow keys, Home, and End. Set aria-selected="true" on a tab in your markup to choose the initial panel; otherwise the first is selected. Add aria-orientation="vertical" to the tablist for a vertical strip. Changing tabs emits a vitre:tabchange event.

Without JavaScript the tab strip is hidden and every panel renders stacked and readable, so give each panel a heading. This keeps the content reachable rather than leaving dead buttons behind.

API

Vitre.apply();
Vitre.apply(document.querySelector("#dynamic-content"), ["alerts", "theme-toggle"]);

Vitre.apply() runs automatically on page load for browser script usage. Call it again after inserting dynamic content. It is idempotent — already-enhanced elements are skipped.

Browser Support

Vitre targets modern browsers and uses current CSS features including cascade layers, color-mix(), :where(), :has(), logical properties, clamp(), and backdrop-filter. It favors a small, expressive stylesheet over legacy fallbacks.

Note

WARNING: This is a new library (May 2026) under active development. You're free to try it, make suggestions, and report problems at https://github.com/vitre-ui/vitre-css/issues, but it comes as-is and without any stated or implied warranty. It is a best effort that I made for myself and I'm making it available for everyone to use for free.