@material/elevation

Elevation

Shadows provide important visual cues about objects’ depth and directional movement. They are the only visual cue indicating the amount of separation between surfaces. An object’s elevation determines the appearance of its shadow. The elevation values are mapped out in a "z-space" and range from 0 to 24.

A note about "z-space": Within the spec, elevation is normally referred to as having a dp value. In other words, how many "pixels" above the base material is a piece of material elevated. On a computer, this is normally represented by a 3-d coordinate system. We like z-space (or just "z" for short) because it aligns with the technical definition of, and nomenclature for, a 3-d coordinate system. Therefore, we feel it makes more sense than dp. However, when we refer to z-space (or z), that can be used interchangeably with the spec's dp.

Design & API Documentation

• Material Design guidelines: Shadows & elevation
• Demo

Installation

npm install @material/elevation

Basic Usage

HTML

Elevation is often already included within the baseline styles of other components (e.g. raised buttons, elevated cards).

However, you can also apply elevation to specific components using mdc-elevation--z<N> classes:

  <div class="mdc-elevation--z1">
    <!-- ... content ... -->
  </div>

Elevation Overlay

The elevation overlay should appear above the component container in the stacking context but below the ripple. To accomplish this, the .mdc-elevation-overlay element should appear before the .mdc-<component>__ripple element in the DOM context. Here's sample markup for a button with a touch target.

<button class="mdc-button mdc-button--raised">
  <div class="mdc-elevation-overlay"></div>
  <div class="mdc-button__ripple"></div>
  <i class="material-icons mdc-button__icon" aria-hidden="true">favorite</i>
  <span class="mdc-button__label">Font Icon</span>
</button>

This ensures the ripple parts are rendered above the overlay.

Styles

@import "@material/elevation/mdc-elevation";

Style Customization

CSS Classes

Some components have a set elevation. For example, a raised MDC Button has elevation 2.

If you want to set the elevation of an element, which is not a Material Design component, you can apply the following CSS classes.

CSS Class	Description
mdc-elevation--z<N>	Sets the elevation to the (N)dp, where 1 <= N <= 24
mdc-elevation-transition	Applies the correct css rules to transition an element between elevations

Sass Mixins, Variables, and Functions

Mixin	Description
mdc-elevation($z-value, $color, $opacity-boost)	Sets the elevation to the z-space for that given elevation, and optionally sets the color and/or boosts the opacity of the shadow
mdc-elevation-overlay-common	Called once per application to setup the universal elevation overlay styles
mdc-elevation-shadow($box-shadow)	Sets the box-shadow of the closest parent selector
mdc-elevation-overlay-surface-position	Sets the positioning of the overlay's surface element so that the overlay can be appropriately centered
mdc-elevation-overlay-dimensions($width, $height: $width, $has-content-sizing: true)	Sets the dimensions of the elevation overlay
mdc-elevation-overlay-fill-color($color)	Sets the color of the elevation overlay
mdc-elevation-overlay-opacity($opacity)	Sets the opacity of the elevation overlay

Function	Description
mdc-elevation-transition-value($duration, $easing)	Returns a value for the transition property to transition an element between elevations
mdc-elevation-overlay-transition-value($duration, $easing)	Returns a value for the transition property to transition the elevation overlay between elevations

Variable	Description
$mdc-elevation-property	Default property for elevation transitions
$mdc-elevation-transition-duration	Default duration value for elevation transitions
$mdc-elevation-transition-timing-function	Default easing value for elevation transitions
$mdc-elevation-overlay-color	Default color for the elevation overlay
$mdc-elevation-overlay-property	Default property for the elevation overlay transitions

If you need more configurability over your transitions, use the mdc-elevation-transition-value function in conjunction with the exported sass variables.

.my-component-with-custom-transitions {

  transition:
    mdc-elevation-transition-value(),
    /* Configure opacity to use same duration and easing values as elevation */
    opacity $mdc-elevation-transition-duration $mdc-elevation-transition-timing-function;
  opacity: .7;
  will-change: $mdc-elevation-property, opacity;
}