@loipham/material-theme

Theme

The Material Design color system can be used to create a color scheme that reflects your brand or style.

Design & API Documentation

• Material Design guidelines: Color

Installation

npm install @loipham/material-theme

Usage

Color Scheme

You can define the theme color variables before importing any MDC Web components:

@use "@loipham/material-theme" with (
  $primary: #fcb8ab,
  $secondary: #feeae6,
  $on-primary: #442b2d,
  $on-secondary: #442b2d,
);
@use "@loipham/material-button/mdc-button";

We suggest you follow the Web Content Accessibility Guidelines 2.0 when picking the values for on-primary, on-secondary, etc. These values should be accessible on top of the corresponding value, e.g. primary and secondary.

https://www.w3.org/TR/WCAG20

Advanced customization

Color scheme will only get you 80% of the way to a well-designed app. Inevitably there will be some components that do not work "out of the box". To fix problems with accessibility and design, we suggest you use our Sass mixins, such as button.filled-accessible(). For more information, consult the documentation for each component.

Text styles

The text styles (referred to as <TEXT_STYLE> below) used in the color system:

Text style	Description
primary	Used for most text (e.g., text-primary-on-light)
secondary	Used for text which is lower in the visual hierarchy (e.g., text-secondary-on-light)
hint	Used for text hints, such as those in text fields and labels (e.g., text-hint-on-light)
disabled	Used for text in disabled components and content (e.g., text-disabled-on-light)
icon	Used for icons (e.g., text-icon-on-light)

Here are the example usages of primary text style:

• CSS Custom property: --mdc-theme-text-primary-on-light
• Class name: mdc-theme--text-primary-on-light
• Property name used in Sass: text-primary-on-light

Non-Sass customization

Only a very limited number of Material Design color customization features are supported for non-Sass clients. They are a set of CSS custom properties, and a set of CSS classes.

CSS Custom Properties

CSS Custom property	Description
--mdc-theme-primary	The theme primary color
--mdc-theme-secondary	The theme secondary color
--mdc-theme-background	The theme background color
--mdc-theme-surface	The theme surface color
--mdc-theme-on-primary	Text color on top of a primary background
--mdc-theme-on-secondary	Text color on top of a secondary background
--mdc-theme-on-surface	Text color on top of a surface background
--mdc-theme-text-<TEXT_STYLE>-on-light	Text color for TEXT_STYLE on top of light background. Please see Text styles section.
--mdc-theme-text-<TEXT_STYLE>-on-dark	Text color for TEXT_STYLE on top of dark background. Please see Text styles section.

CSS Classes

CSS Class	Description
mdc-theme--primary	Sets the text color to the theme primary color
mdc-theme--secondary	Sets the text color to the theme secondary color
mdc-theme--background	Sets the background color to the theme background color
mdc-theme--surface	Sets the surface color to the theme surface color
mdc-theme--on-primary	Sets the text color to the theme on-primary color
mdc-theme--on-secondary	Sets the text color to the theme on-secondary color
mdc-theme--on-surface	Sets the text color to the theme on-surface color
mdc-theme--primary-bg	Sets the background color to the theme primary color
mdc-theme--secondary-bg	Sets the background color to the theme secondary color
mdc-theme--text-<TEXT_STYLE>-on-light	Sets text to a suitable color for TEXT_STYLE on top of light background. Please see Text styles section.
mdc-theme--text-<TEXT_STYLE>-on-dark	Sets text to a suitable color for TEXT_STYLE on top of dark background. Please see Text styles section.

Sass Mixins, Variables, and Functions

Mixin	Description
property($property, $value, $gss, $important)	Applies a dynamic value to the specified property. The value may be a standard CSS value, a custom property Map, or a Material theme key.

Material theme keys with theme.property()

Material theme key names below can be used as the $value argument for the theme.property() mixin. Some keys are dynamic, and change context depending on other key values. Keys may also translate to custom properties for dynamic runtime theming.

Key Name	Description
primary	The theme primary color
secondary	The theme secondary color
background	The theme background color
surface	The theme surface color
text-<TEXT_STYLE>-on-light	TEXT_STYLE on top of a light background. Please see Text styles section.
text-<TEXT_STYLE>-on-dark	TEXT_STYLE on top of a dark background. Please see Text styles section.
on-primary	A text/iconography color that is usable on top of primary color
on-secondary	A text/iconography color that is usable on top of secondary color
on-surface	A text/iconography color that is usable on top of surface color

Custom properties with theme.property()

The theme.property() mixin also accepts a custom property Map for the $value argument. The map must contain a varname key with the name of the custom property, and an optional fallback key with the value of the custom property.

Use the @loipham/material-theme/custom-properties module to create custom property Maps.

For example, the following Sass...

@use "@loipham/material-theme";
@use "@loipham/material-theme/custom-properties";

.foo {
  @include theme.property(color, custom-properties.create(--foo-color, red));
}

...will produce the following CSS...

.foo {
  color: red;
  color: var(--foo-color, red);
}

The above output CSS will apply the fallback field's value for all supported browsers (including IE11) while allowing for CSS custom property use as a progressive enhancement. Browsers like IE11 that do not support CSS custom properties will apply the color: red; and ignore the color: var(--foo-color, red);. This argument type is intended for clients who need custom color application outside of the existing theme properties.

theme.luminance($color)

Calculates the luminance value (0 - 1) of a given color.

@debug theme.luminance(#9c27b0); // 0.11654

theme.contrast($back, $front)

Calculates the contrast ratio between two colors.

@debug theme.contrast(#9c27b0, #000); // 3.33071

theme.tone($color)

Determines whether the given color is "light" or "dark".

If the input color is a string literal equal to "light" or "dark", it will be returned verbatim.

@debug theme.tone(#9c27b0); // dark
@debug theme.tone(light);   // light

theme.contrast-tone($color)

Determines whether to use light or dark text on top of a given color.

@debug theme.contrast-tone(#9c27b0); // light

theme.accessible-ink-color($fill-color, $text-style: primary)

Returns an accessible ink color that has sufficient contrast against the given fill color.

Params:

• $fill-color: Supports the same values as theme.prop-value
• $text-style: Value must be one of primary, secondary, hint, disabled, icon (see $text-colors)

NOTE: This function is defined in _variables.scss instead of _functions.scss to avoid circular imports.

@debug theme.accessible-ink-color(secondary); // rgba(0, 0, 0, .87) (text-primary-on-light)
@debug theme.accessible-ink-color(blue);      // white              (text-primary-on-dark)

theme.text-emphasis($emphasis)

Returns opacity value for given emphasis.

Params:

• $emphasis: Type of emphasis such as high, medium & disabled.

@debug theme.text-emphasis(high); // .87
@debug theme.text-emphasis(disabled); // .38