Enum SizeClass 

pub enum SizeClass {
    Compact,
    Medium,
    Expanded,
}

How much screen there is, independent of what is pointing at it.

The second axis, and the one Density kept being asked to carry. A phone is small and touch; a tablet and a touchscreen laptop are big and touch; a half-width window on a desktop is small and pointer. Those are four real combinations and one axis cannot name them, which is what made the old Touch preset tighten shells it had no business tightening.

Boundaries are quoted, not derived, for the same reason the Gap values are: a derived boundary is one nobody can check. They are Material 3’s window size classes, the best-known three-tier split with published numbers. Apple’s size classes are two-tier and expressed as regular/compact per axis, which does not give a middle to aim at.

Source: https://m3.material.io/foundations/layout/applying-layout/window-size-classes

This enum carries the boundaries only. What appears, disappears or reflows at each is a product decision and belongs to makeover-touch, not here. Deliberately absent for now: size class does not feed Gap::step_at. Whether shells should tighten on a compact window is a look call of exactly the kind that produced the 2026-07-29 demolition, so it waits for an eyeball rather than being derived a second time.

Variants

Compact

Under 600px. Phones in either orientation, and any window narrowed to phone width regardless of what is pointing at it.

Medium

600px to 839px. Small tablets, split-screen panes, half-width windows.

Expanded

840px and up. Laptops, desktops, tablets in landscape.

Implementations

impl SizeClass

pub const fn min_px(self) -> u16

Lower bound in CSS pixels, inclusive. Self::Compact starts at zero.

pub fn media_condition(self) -> String

The media condition selecting exactly this class, without the @media.

Bounded on both sides for the middle class, so the three are mutually exclusive and a rule cannot land in two of them. max-width is one below the next class’s min_px, because CSS width ranges are inclusive.

pub const fn token(self) -> &'static str

The CSS class name an app may hang off this, without the leading dot.

pub const fn all() -> [Self; 3]

Every class, narrowest first.

pub const fn at_width(px: u16) -> Self

The class a given viewport width falls in.

Trait Implementations

impl Clone for SizeClass

fn clone(&self) -> SizeClass

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for SizeClass

impl Debug for SizeClass

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for SizeClass

fn default() -> SizeClass

Returns the “default value” for a type.

impl Eq for SizeClass

impl Hash for SizeClass

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for SizeClass

fn cmp(&self, other: &SizeClass) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for SizeClass

fn eq(&self, other: &SizeClass) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialOrd for SizeClass

fn partial_cmp(&self, other: &SizeClass) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralPartialEq for SizeClass