Button — native actions for agent UIs (HTML/CSS)

Specimen

One framed specimen with Preview, Code, and Install. Copy the active panel; raw files stay linked below.

Preview

Try the violet button. It enters data-au-state="loading", then returns a local success state.

Code

button.html

<style>
.au-btn {
  --au-btn-bg: transparent;
  --au-btn-fg: var(--au-fg);
  --au-btn-border: transparent;
  --au-btn-radius: var(--au-radius-md);
  --au-btn-height: 40px;
  --au-btn-padding-inline: 16px;
  --au-btn-gap: 8px;

  appearance: none;
  align-items: center;
  border: 1px solid var(--au-btn-border);
  border-radius: var(--au-btn-radius);
  cursor: pointer;
  display: inline-flex;
  font-family: var(--au-font-sans);
  font-size: 13px;
  font-weight: 600;
  gap: var(--au-btn-gap);
  justify-content: center;
  letter-spacing: -0.01em;
  line-height: 1;
  min-height: var(--au-btn-height);
  padding: 0 var(--au-btn-padding-inline);
  position: relative;
  text-decoration: none;
  transition:
    background-color var(--au-duration-fast) var(--au-ease),
    border-color var(--au-duration-fast) var(--au-ease),
    box-shadow var(--au-duration-fast) var(--au-ease),
    color var(--au-duration-fast) var(--au-ease),
    transform var(--au-duration-fast) var(--au-ease);
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.au-btn:hover:not(:disabled) {
  background: var(--au-btn-bg-hover, var(--au-btn-bg));
  border-color: var(--au-btn-border-hover, var(--au-btn-border));
  color: var(--au-btn-fg-hover, var(--au-btn-fg));
}

.au-btn:focus-visible {
  box-shadow: var(--au-focus-ring);
  outline: 2px solid var(--au-focus);
  outline-offset: 2px;
}

.au-btn:active:not(:disabled) {
  transform: translateY(1px);
}

.au-btn:disabled,
.au-btn[aria-disabled="true"] {
  cursor: not-allowed;
  opacity: 0.48;
}

.au-btn--primary {
  --au-btn-bg: var(--au-action);
  --au-btn-bg-hover: var(--au-action-hover);
  --au-btn-fg: var(--au-action-fg);
  --au-btn-border: var(--au-action);
}

.au-btn--secondary {
  --au-btn-bg: var(--au-surface);
  --au-btn-bg-hover: var(--au-surface-hover);
  --au-btn-border: var(--au-border-emphasis);
}

.au-btn--ghost {
  --au-btn-bg: transparent;
  --au-btn-bg-hover: var(--au-surface-muted);
  --au-btn-border: transparent;
}

.au-btn--danger {
  --au-btn-bg: var(--au-danger);
  --au-btn-bg-hover: color-mix(in srgb, var(--au-danger) 86%, var(--au-fg));
  --au-btn-fg: #ffffff;
  --au-btn-border: var(--au-danger);
}

.au-btn--link {
  --au-btn-bg: transparent;
  --au-btn-bg-hover: var(--au-action-soft);
  --au-btn-fg: var(--au-action);
  --au-btn-border: transparent;
  min-height: auto;
  padding-inline: 4px;
}

.au-btn--sm {
  --au-btn-height: 32px;
  --au-btn-padding-inline: 12px;
  font-size: 12px;
}

.au-btn--lg {
  --au-btn-height: 48px;
  --au-btn-padding-inline: 20px;
  font-size: 14px;
}

.au-btn--icon {
  --au-btn-height: 40px;
  --au-btn-padding-inline: 0;
  aspect-ratio: 1;
  width: var(--au-btn-height);
}

.au-btn[data-au-state="loading"] {
  cursor: wait;
  pointer-events: none;
}

.au-btn[data-au-state="loading"]::before {
  border: 1.5px solid currentColor;
  border-right-color: transparent;
  border-radius: 50%;
  content: "";
  height: 13px;
  width: 13px;
  animation: au-button-spin 700ms linear infinite;
}

.au-btn[data-au-state="loading"] > * {
  opacity: 0.68;
}

@keyframes au-button-spin {
  to { transform: rotate(360deg); }
}

@media (prefers-reduced-motion: reduce) {
  .au-btn,
  .au-btn[data-au-state="loading"]::before {
    animation: none;
    transition-duration: 0.01ms;
  }
}
</style>

<!-- agent-ui button: requires tokens.css and button.css. No JavaScript required. -->
<button class="au-btn au-btn--primary" type="button">Run component</button>

Install

head.html

<link rel="stylesheet" href="tokens.css">
<link rel="stylesheet" href="components/button/button.css">

Component contract

Dependencies: tokens.css and button.css. No runtime or icon library.
Variants: primary, secondary, ghost, danger, link, icon.
States: Native hover, focus, active, disabled; data-au-state="loading" for pending work.
Events: Native click and form events. No custom event required.
No JavaScript: Remains keyboard-accessible and submits normal forms without agent-ui.js.
CSS variables: --au-btn-bg, --au-btn-fg, --au-btn-border, --au-btn-radius, --au-btn-height.

Accessibility and safety

Native first

Use a native <button> for actions and a native <a> for navigation. Icon-only buttons need an accessible label. Dynamic labels stay text, never HTML.