Surfaces

Material Design has three-dimensional qualities that are reflected in its use of surfaces, depth, and shadows.


Material environment

The physical world

In the physical world, objects can be stacked or attached to one another, but cannot pass through each other. They cast shadows and reflect light....

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In the physical world, objects can be stacked or attached to one another, but cannot pass through each other. They cast shadows and reflect light.

Material Design reflects these qualities in how surfaces are displayed and move across the Material UI. Surfaces, and how they move in three dimensions, are communicated in ways that resemble how they move in the physical world. This spatial model can also be applied consistently across apps.

Depth

Material Design UIs are displayed in an environment that expresses three-dimensional (3D) space using light, surfaces, and cast shadows. All elements in the Material environment...

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Material Design UIs are displayed in an environment that expresses three-dimensional (3D) space using light, surfaces, and cast shadows. All elements in the Material environment move horizontally, vertically, and at varying depths along the z-axis. Depth is depicted by placing elements at various points along the positive z-axis extending towards the viewer.

On the web, the UI expresses 3D space by manipulating the y-axis.

3D space with x, y, and z axes


Properties

Material surfaces have consistent, unchangeable characteristics and behaviors across Material Design.

Dimensions

Material has varying x & y dimensions (measured in dp) and a uniform thickness (1dp).

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Material has varying x & y dimensions (measured in dp) and a uniform thickness (1dp).

Do.

The height and width of material can vary.

Don’t.

Material is always 1dp thick.

Shadows

Material surfaces at different elevations cast shadows.

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Material surfaces at different elevations cast shadows.

Do.

Shadows show the elevation of different Material surfaces.

  1. Top view
  2. Isometric 3D view showing the shadow cast by light when the material moves upwards

Don’t.

Don’t express shadows without changing a surface’s elevation.

  1. Top view
  2. Isometric 3D view depicts a shadow using only color, rather than light and elevation

Resolution

Material has infinite resolution.

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Material has infinite resolution.

Material has infinite resolution.

Content

Content is displayed in any shape and color on Material. Content does not add thickness to Material. Content is expressed without being a separate layer.

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Content is displayed in any shape and color on Material. Content does not add thickness to Material. Content is expressed without being a separate layer.

Do.

Material can display any shape and color. Content can behave independent of Material, but is limited within the bounds of Material.

Do.

Content behavior can be independent of surface behavior.

Do.

Content behavior can depend on Material behavior.

Physical properties

Material is solid. User input and interaction cannot pass through material. Multiple Material elements cannot occupy the same point in space simultaneously. Material cannot pass...

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Material is solid. User input and interaction cannot pass through material.

Do.

Input events only affect the surface of Material.

Don’t.

Input events cannot pass through Material.

Multiple Material elements cannot occupy the same point in space simultaneously.

Do.

Prevent multiple Material elements from simultaneously occupying the same point in space, such as by separating elements with elevation.

Don’t.

Multiple Material elements cannot occupy the same point in space simultaneously.

Material cannot pass through other Material. For example, one Material surface cannot pass through another Material surface when changing elevation.

Don’t.

Material cannot pass through other Material.

Material does not behave like a gas.

Don’t.

Material does not behave like a gas.

Do.

Material enters and exits through changes in opacity, size, or position.

Material is not fluid like a liquid or gel, though it may display content with these properties.

Don’t.

Material does not behave like a liquid or gel.

Don’t.

Material does not behave like a liquid.

Transforming Material

Material can change shape. Material can change opacity. Material grows and shrinks only along its plane. Material bends or folds within the depth of the...

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Material can change shape.

Material can change shape.

Material can change opacity.

  1. Material can change opacity uniformly across its entire surface.
  2. Material can change opacity across a portion of its surface.

Material grows and shrinks only along its plane.

Do.

Material grows and shrinks only along its plane.

Material bends or folds within the depth of the UI.

Don’t.

Material never bends or folds in ways that exceed the depth of the UI.

Material surfaces can join together to become a single Material surface.

Multiple Material surfaces can join together to become a single surface.

When split, Material can rejoin. For example, if you remove a portion of Material from a surface, the surface will become whole again.

Material can split and become whole again.

Movement

Material can be spontaneously generated or dismissed anywhere in the environment. Material can move along any axis. Material surfaces can coordinate their motion. Material motion...

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Material can be spontaneously generated or dismissed anywhere in the environment.

Material can be spontaneously generated or dismissed.

Material can move along any axis.

Material can move along various axes.

Material surfaces can coordinate their motion.

Material surfaces can coordinate their motion.

Material motion along the z-axis is typically a result of user interaction.

Material surfaces exhibiting z-axis motion prompted by user interaction.


Attributes

Basic Material surface

The basic Material surface is opaque white, with 1dp thickness, and casts a shadow. All UI elements in Material Design result from modifications to this...

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The basic Material surface is opaque white, with 1dp thickness, and casts a shadow. All UI elements in Material Design result from modifications to this surface.

Behavior

Material surfaces can behave in certain ways: Surfaces can be divided into areas which display different types of behavior.

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Material surfaces can behave in certain ways:

  • Rigid surfaces remain the same size through all interactions.
  • Stretchable surfaces can grow or shrink along one or more edges up to a size limit, then behave as rigid surfaces.
  • Pannable surfaces remain the same size throughout interactions. They can display additional content upon scrolling within the area, until reaching a content limit. When this limit is reached, they behave as rigid surfaces in that scroll direction.

Material surface dimensions can be fixed with all content initially visible. The surface retains that size through all interactions.

Material surface dimensions can grow along one or more axes to accommodate additional content.

Material surface dimensions can remain rigid, but content can scroll or pan across the surface.

Composite surfaces

Surfaces can be divided into areas which display different types of behavior.

A single surface can contain multiple pannable surfaces, such as an embedded map (1) that pans independently of a scrollable list (2).

A card can stretch to display a region that scrolls independently of other card content.

Stretchable surfaces

A stretchable surface can be stretched before reaching a limit, at which point the entire surface becomes rigid. Surfaces can stretch vertically, horizontally, or in...

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A stretchable surface can be stretched before reaching a limit, at which point the entire surface becomes rigid. Surfaces can stretch vertically, horizontally, or in both directions.

Typically, user interaction with a surface will stretch it in one direction. For example, tapping “more details” can cause a card to grow vertically and display additional content.

Material stretch direction can be exclusively vertical.

Material stretch direction can be exclusively horizontal.

Material stretch direction can be along both horizontal and vertical axes, either independently or simultaneously.

Surface positioning and movement (x/y)

Surfaces can remain in a fixed position on the x- and y-axes, or can be moveable in any direction. Surface movement can be confined to...

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Surfaces can remain in a fixed position on the x- and y-axes, or can be moveable in any direction.

Surface movement can be confined to a single axis, allow movement along a single axis at a time, or allow movement along both axes simultaneously.

Surfaces can remain in a fixed position. The top app bar (1) remains in a fixed position while the card collection (2) scrolls only vertically behind it.

Surfaces (1,2) can move in any direction, although movement can be confined to a single axis at a time.

Surfaces can move in any direction.

Surfaces can move independently of each other, or their movement can affect or be dependent upon the movement of other surfaces.

A dependency can be based on a variety of mechanics, such as nearby surfaces moving when another surface expands, or the proportion of movement between surfaces moving in parallax.

Surfaces can move independently of each other.

One surface’s movement can depend upon another’s movement.

Surface opacity

Material surfaces can be transparent, semi-transparent, or opaque.

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Material surfaces can be transparent, semi-transparent, or opaque.

Text on transparent and semi-transparent surfaces may require background treatment to preserve legibility.

Transparent surfaces lack clear edges, making it difficult to determine where surfaces begin and end, and which surface content belongs to.

Caution.

  1. Content on transparent or semi-transparent surfaces may need a background treatment to preserve legibility.
  2. Isometric view

Don’t.

  1. Don’t use transparent surfaces, as they have no opacity, making it difficult to identify the surface on which content appears. This top app bar is transparent, making it unclear if the text appears on the app bar or the surface behind it.
  2. Isometric view

Scrim

Scrims are temporary treatments that can be applied to Material surfaces for the purpose of making content on a surface less prominent. They help direct...

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Scrims are temporary treatments that can be applied to Material surfaces for the purpose of making content on a surface less prominent. They help direct user attention to other parts of the screen, away from the surface receiving a scrim.

Scrims can be applied in a variety of ways, including:

  • Darkening or lightening the surface and its content
  • Reducing the opacity of the surface and its content

Multiple surfaces on a screen at a time can display scrims. Scrims can appear at any elevation, whether in the foreground or background.

Foreground content attracts more attention when background content displays a scrim.

A scrim lightens content displayed on the front surface and directs attention to the surface behind it.