Button States

---
name: button-states
description: Every interactive element needs a complete set of visual states — rest, hover, active/pressed, focus, disabled, and loading. States should be derived algorithmically from the base colour, not chosen arbitrarily. Use when designing buttons, links, inputs, or any clickable component.
metadata:
  priority: 8
  pathPatterns:
    - "components/**"
    - "src/components/**"
    - "**/*.css"
    - "**/*.scss"
    - "**/tokens/**"
    - "**/*.tsx"
    - "**/*.jsx"
    - "design-system/**"
  promptSignals:
    phrases:
      - "hover state"
      - "active state"
      - "focus state"
      - "disabled"
      - "button states"
      - "interactive states"
      - "loading state"
      - "pressed"
retrieval:
  aliases:
    - button states
    - hover state
    - interactive states
    - focus ring
    - disabled state
    - loading button
  intents:
    - design button states
    - add hover and active states
    - style focus ring
    - handle disabled state
    - add loading state to button
  examples:
    - what colour should the hover state be
    - design all states for this button
    - how do I show a loading state on a button
    - make the focus ring visible
---

# Button and Interactive Element States

Every interactive component must have a complete, visually distinct state for each interaction mode. Missing or ambiguous states make the UI feel unfinished and reduce user confidence.

## The Six States

| State | Trigger | Visual signal |
|---|---|---|
| **Rest** | Default | Base colour, cursor: pointer |
| **Hover** | Mouse over | Slightly darker, subtle background shift |
| **Active / Pressed** | Mouse down / tap | Noticeably darker, slight scale-down |
| **Focus** | Keyboard navigation | Visible focus ring, no change to fill |
| **Disabled** | Not available | Low contrast, cursor: not-allowed, no interaction |
| **Loading** | Async action in progress | Spinner or pulse, non-interactive |

## Deriving State Colours Algorithmically

State colours are not chosen independently — they are derived from the base colour by adjusting lightness in HSL. This guarantees coherence across the entire palette.

```
base:     hsl(H, S%, L%)
hover:    hsl(H, S%, L% - 8%)    ← darken 8%
active:   hsl(H, S%, L% - 14%)   ← darken 14%
```

### Example: primary button `#635BFF` (hsl 243, 100%, 68%)

```css
.btn-primary {
  background: hsl(243, 100%, 68%);       /* rest    #635BFF */
}
.btn-primary:hover {
  background: hsl(243, 100%, 60%);       /* hover   #4A40FF */
}
.btn-primary:active {
  background: hsl(243, 100%, 54%);       /* active  #3429FF */
}
```

For light buttons on dark backgrounds, invert the logic — lighten on hover instead of darkening.

### Secondary / outlined buttons

```css
.btn-secondary {
  background: transparent;
  border: 1px solid var(--color-border);
  color: var(--color-text);
}
.btn-secondary:hover {
  background: var(--color-grey-100);     /* subtle fill */
  border-color: var(--color-grey-300);
}
.btn-secondary:active {
  background: var(--color-grey-200);
}
```

## Focus State

Focus is a keyboard navigation requirement (WCAG 2.2). It must be visible and must not rely on the hover style alone — keyboard users do not trigger hover.

```css
.btn:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
}
```

- Use `outline`, not `box-shadow`, for focus rings — `outline` respects `border-radius` in modern browsers and does not affect layout
- `outline-offset: 2–4px` gives the ring breathing room from the component edge
- Never use `outline: none` without a replacement focus style

## Disabled State

```css
.btn:disabled,
.btn[aria-disabled="true"] {
  opacity: 0.4;
  cursor: not-allowed;
  pointer-events: none;
}
```

- Disabled elements are exempt from WCAG contrast requirements — low opacity is correct and intentional
- Use `pointer-events: none` to prevent click events even if JS is bypassed
- Do not change the shape or size of a disabled button — only colour and cursor change

## Loading State

When a button triggers an async action, replace the label with a spinner and prevent re-submission.

```css
.btn--loading {
  pointer-events: none;
  cursor: wait;
  opacity: 0.7;
}
```

- Keep the button width stable during loading — avoid layout shift when label is replaced by spinner
- Return to rest state on completion (success or error)
- For long-running operations, pair with a status message — a spinner alone does not tell the user what is happening

## Scale on Active (Optional)

A subtle scale-down on press adds physical feedback — borrowed from Disney's squash principle.

```css
.btn:active {
  transform: scale(0.97);
  transition: transform 80ms ease-out;
}
```

Keep the scale value between `0.95–0.98`. Below `0.95` feels like the button is breaking.

## Complete Button CSS Reference

```css
.btn {
  cursor: pointer;
  background: var(--color-primary);
  color: white;
  border-radius: var(--radius-button);
  padding: var(--component-padding-y-md) var(--component-padding-x-md);
  height: var(--component-height-md);
  border: none;
  transition: background 120ms ease-out, transform 80ms ease-out;
}

.btn:hover           { background: var(--color-primary-hover); }
.btn:active          { background: var(--color-primary-active); transform: scale(0.97); }
.btn:focus-visible   { outline: 2px solid var(--color-primary); outline-offset: 3px; }
.btn:disabled        { opacity: 0.4; cursor: not-allowed; pointer-events: none; }
.btn.btn--loading    { opacity: 0.7; cursor: wait; pointer-events: none; }
```

## Review Checklist

- [ ] Does every interactive element have all six states defined?
- [ ] Are hover and active colours derived from the base by lightness adjustment (not chosen arbitrarily)?
- [ ] Is focus state visible and using `outline` (not removed)?
- [ ] Is disabled state low-opacity with `cursor: not-allowed`?
- [ ] Does loading state prevent re-submission?
- [ ] Are transition durations 80–150ms — not instant, not slow?
- [ ] Does `cursor: pointer` appear on all interactive elements at rest?