One HTML file. A button. State. That’s it.

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
  <title>SvenJS</title>
  <style>:root {
  color-scheme: light dark;
  --bg: light-dark(#f7f1ea, #141210);
  --fg: light-dark(#1c1712, #f2ebe3);
  --muted: light-dark(#6b6158, #a3988c);
  --line: light-dark(color-mix(in oklab, #1c1712 12%, transparent), color-mix(in oklab, #f2ebe3 14%, transparent));
  --accent: light-dark(#c45c20, #e07a3d);
  --accent-fg: #fff;
  --card: light-dark(#fffdf9, #1c1915);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  min-height: 100%;
  background: var(--bg);
  color: var(--fg);
  font: 16px/1.5 "IBM Plex Sans", ui-sans-serif, system-ui, sans-serif;
}

#app { min-height: 100%; padding: 1.25rem; }

button, input, textarea {
  font: inherit;
  color: inherit;
}

button {
  cursor: pointer;
  background: var(--accent);
  color: var(--accent-fg);
  border: 0;
  border-radius: 8px;
  padding: 0.55rem 0.95rem;
}

button:hover { filter: brightness(1.05); }

input[type="text"] {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 0.5rem 0.7rem;
}

.demo-card {
  max-width: 28rem;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 1.25rem 1.4rem;
}

.demo-card h1, .demo-card h2, .demo-card h3 {
  font-family: Newsreader, Georgia, serif;
  font-weight: 650;
  margin: 0 0 0.75rem;
}

.demo-card p { color: var(--muted); margin: 0.75rem 0 0; }

.todo-app { max-width: 32rem; margin: 0 auto; }
.todo-app h1 {
  font-family: Newsreader, Georgia, serif;
  font-weight: 650;
  font-size: 2.4rem;
  margin: 0 0 1rem;
  letter-spacing: -0.03em;
}
.todo-list { list-style: none; margin: 1rem 0; padding: 0; }
.todo-list li {
  display: flex;
  gap: 0.6rem;
  align-items: center;
  padding: 0.55rem 0;
  border-bottom: 1px solid var(--line);
}
.todo-list li.done label { color: var(--muted); text-decoration: line-through; }
.todo-list .destroy {
  margin-left: auto;
  background: transparent;
  color: var(--muted);
  padding: 0.2rem 0.45rem;
}
.todo-filters { display: flex; gap: 0.5rem; flex-wrap: wrap; }
.todo-filters a {
  color: var(--fg);
  text-decoration: none;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 0.2rem 0.7rem;
  font-size: 0.85rem;
}
.todo-filters a.selected { border-color: var(--accent); color: var(--accent); }
.compose-grid { display: grid; gap: 0.75rem; }
.compose-grid > * {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 1rem 1.1rem;
}

.svenjs-credit {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--ink, #312725);
  background: var(--field, #fffdf8);
  border: 1px solid var(--rule, #d9d0c0);
  padding: 6px 14px 6px 6px;
  margin-top: 1.5rem;
}
.svenjs-credit:hover {
  border-color: var(--accent, #e07a3d);
}
.svenjs-mark {
  display: block;
  width: 36px;
  height: 36px;
  border-radius: 8px;
}
.svenjs-credit-copy {
  display: flex;
  flex-direction: column;
  gap: 1px;
  line-height: 1.15;
}
.svenjs-credit-kicker {
  font-size: 0.68rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted, #6a5e50);
}
.svenjs-credit-name {
  font-size: 0.95rem;
  font-weight: 600;
}
</style>
</head>
<body>
  <div id="app"></div>
  <script src="https://unpkg.com/svenjs@3.4.0"></script>
  <script type="importmap">{"imports":{"svenjs":"data:text/javascript,export%20const%20%7B%20Fragment%2C%20create%2C%20createStore%2C%20flushSync%2C%20h%2C%20html%2C%20hydrate%2C%20jsx%2C%20jsxDEV%2C%20jsxs%2C%20render%2C%20renderToString%2C%20unmountRoot%2C%20version%20%7D%20%3D%20globalThis.Svenjs%3B%20export%20default%20globalThis.Svenjs.default%20%3F%3F%20globalThis.Svenjs%3B","svenjs/jsx-runtime":"data:text/javascript,export%20const%20%7B%20Fragment%2C%20create%2C%20createStore%2C%20flushSync%2C%20h%2C%20html%2C%20hydrate%2C%20jsx%2C%20jsxDEV%2C%20jsxs%2C%20render%2C%20renderToString%2C%20unmountRoot%2C%20version%20%7D%20%3D%20globalThis.Svenjs%3B%20export%20default%20globalThis.Svenjs.default%20%3F%3F%20globalThis.Svenjs%3B","svenjs/jsx-dev-runtime":"data:text/javascript,export%20const%20%7B%20Fragment%2C%20create%2C%20createStore%2C%20flushSync%2C%20h%2C%20html%2C%20hydrate%2C%20jsx%2C%20jsxDEV%2C%20jsxs%2C%20render%2C%20renderToString%2C%20unmountRoot%2C%20version%20%7D%20%3D%20globalThis.Svenjs%3B%20export%20default%20globalThis.Svenjs.default%20%3F%3F%20globalThis.Svenjs%3B"}}</script>
<script type="module">
const { create, render, html } = Svenjs;

const App = create({
  initialState: { clicks: 0 },
  render() {
    return html`
      <div class="demo-card">
        <h1>The Click App</h1>
        <button onClick=${() => this.setState({ clicks: this.state.clicks + 1 })}>
          Why not click me?
        </button>
        <p>You have clicked ${this.state.clicks} times.</p>
      </div>
    `;
  },
});

render(App, document.getElementById("app"));

</script>
  <a class="svenjs-credit" href="https://svenjs.xyz/" rel="noopener noreferrer">
  <svg class="svenjs-mark" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 326 326" width="36" height="36" aria-hidden="true">
    <rect width="326" height="326" rx="72" fill="#312725"/>
    <g fill="#e07a3d" transform="translate(0 4)">
      <polygon points="127,73 258,73 204,130 78,129"/>
      <polygon points="78,129 121,129 172,184 131,184"/>
      <polygon points="154,139 198,139 249,195 205,195"/>
      <polygon points="116,193 249,195 199,250 66,250"/>
    </g>
  </svg>
  <span class="svenjs-credit-copy">
    <span class="svenjs-credit-kicker">UI built with</span>
    <span class="svenjs-credit-name">SvenJS 3.4.0</span>
  </span>
</a>
</body>
</html>