# Flex

Set how flex items grow & shrink.

**Widely available.** This feature is well established and works across many devices and browser versions.

Chrome 29 · Edge 12 · Firefox 20 · Safari 9

| Class | Properties | Value |
|-------|------------|-------|
| `f:1` | flex | `1` |
| `f:2` | flex | `2` |
| `f:3` | flex | `3` |
| `f:4` | flex | `4` |
| `f:5` | flex | `5` |
| `f:6` | flex | `6` |
| `f:auto` | flex | `auto` |
| `f:none` | flex | `none` |

## Variants

Prefix any class with a variant to apply it only under that condition. Variants stack, as in `@md:h:f:4`.

### Breakpoints

Apply a class from a viewport width up. Each breakpoint covers its width & every width above it.

| Class | Applies |
|-------|---------|
| `@xs:f:4` | From 32rem up. |
| `@sm:f:4` | From 40rem up. |
| `@md:f:4` | From 48rem up. |
| `@lg:f:4` | From 64rem up. |
| `@xl:f:4` | From 80rem up. |
| `@xxl:f:4` | From 96rem up. |

### Containers

Apply a class from a container's width up, not the viewport's. Mark the parent with `ct:is` first.

| Class | Applies |
|-------|---------|
| `@c:xs:f:4` | Container from 32rem up. |
| `@c:sm:f:4` | Container from 40rem up. |
| `@c:md:f:4` | Container from 48rem up. |
| `@c:lg:f:4` | Container from 64rem up. |
| `@c:xl:f:4` | Container from 80rem up. |
| `@c:xxl:f:4` | Container from 96rem up. |

### Media

Apply a class when the device or the page matches a condition, or on the first frame an element renders.

| Class | Applies |
|-------|---------|
| `@pc:f:4` | On a touch screen. |
| `@prm:f:4` | With reduced motion on. |
| `@st:f:4` | On the first frame. |

### States

Apply a class only while the element is in a state, such as hovered, focused or checked.

| Class | Applies |
|-------|---------|
| `h:f:4` | On :hover. |
| `f:f:4` | On :focus. |
| `fv:f:4` | On :focus-visible. |
| `a:f:4` | On :active. |
| `d:f:4` | On :disabled. |
| `fc:f:4` | On :first-child. |
| `c:f:4` | On :checked. |
| `e:f:4` | On :empty. |
| `fw:f:4` | On :focus-within. |
| `i:f:4` | On :invalid. |
| `in:f:4` | On :indeterminate. |
| `lc:f:4` | On :last-child. |
| `nc:f:4` | On :nth-child. |
| `r:f:4` | On :required. |
| `ro:f:4` | On :read-only. |
| `v:f:4` | On :valid. |

### Pseudo Elements

Style a part of the element rather than the element itself, such as its placeholder or the selected text.

| Class | Applies |
|-------|---------|
| `a::f:4` | On ::after. |
| `b::f:4` | On ::before. |
| `p::f:4` | On ::placeholder. |
| `s::f:4` | On ::selection. |