Bootstrap buttons

Bootstrap button component for actions in tables, forms, cards, and more. CoreUI 4 for Bootstrap provides various styles, states, and size. Ready to use and easy to customize.

Other frameworks

CoreUI components are available as native Angular, React, and Vue components. To learn more please visit the following pages.

On this page

Base class

CoreUI has a base .btn class that sets up basic styles such as padding and content alignment. By default, .btn controls have a transparent border and background color, and lack any explicit focus and hover styles.

html

<button type="button" class="btn">Base class</button>

The .btn class is intended to be used in conjunction with our button variants, or to serve as a basis for your own custom styles.

If you are using the .btn class on its own, remember to at least define some explicit :focus and/or :focus-visible styles.

Variants

CoreUI includes a bunch of predefined Bootstrap buttons, each serving its own semantic purpose. CoreUI also offers some unique buttons styles.

Buttons show what action will happen when the user clicks or touches it. Bootstrap buttons are used to initialize operations, both in the background or foreground of an experience.

html

<button type="button" class="btn btn-primary">Primary</button>
<button type="button" class="btn btn-secondary">Secondary</button>
<button type="button" class="btn btn-success">Success</button>
<button type="button" class="btn btn-danger">Danger</button>
<button type="button" class="btn btn-warning">Warning</button>
<button type="button" class="btn btn-info">Info</button>
<button type="button" class="btn btn-light">Light</button>
<button type="button" class="btn btn-dark">Dark</button>

<button type="button" class="btn btn-link">Link</button>

Conveying meaning to assistive technologies

Using color to add meaning only provides a visual indication, which will not be conveyed to users of assistive technologies – such as screen readers. Ensure that information denoted by the color is either obvious from the content itself (e.g. the visible text), or is included through alternative means, such as additional text hidden with the .visually-hidden class.

With icons

You can combine button with our CoreUI Icons.

html

<button type="button" class="btn btn-primary"><span class="cil-contrast"></span> Primary</button>
<button type="button" class="btn btn-secondary"><span class="cil-contrast"></span> Secondary</button>
<button type="button" class="btn btn-success"><span class="cil-contrast"></span> Success</button>
<button type="button" class="btn btn-danger"><span class="cil-contrast"></span> Danger</button>
<button type="button" class="btn btn-warning"><span class="cil-contrast"></span> Warning</button>
<button type="button" class="btn btn-info"><span class="cil-contrast"></span> Info</button>
<button type="button" class="btn btn-light"><span class="cil-contrast"></span> Light</button>
<button type="button" class="btn btn-dark"><span class="cil-contrast"></span> Dark</button>

<button type="button" class="btn btn-link">Link</button>

Disable text wrapping

If you don’t want the button text to wrap, you can add the .text-nowrap class to the button. In Sass, you can set $btn-white-space: nowrap to disable text wrapping for each button.

Button tags

The .btn classes are designed for <button> , <a> or <input> elements (though some browsers may apply a slightly different rendering).

If you’re using .btn classes on <a> elements that are used to trigger functionality ex. collapsing content, these links should be given a role="button" to adequately communicate their meaning to assistive technologies such as screen readers.

Link

html

<a class="btn btn-primary" href="#" role="button">Link</a>
<button class="btn btn-primary" type="submit">Button</button>
<input class="btn btn-primary" type="button" value="Input">
<input class="btn btn-primary" type="submit" value="Submit">
<input class="btn btn-primary" type="reset" value="Reset">

Outline buttons

If you need a button, but without the strong background colors. Replace the default modifier classes with the .btn-outline-* ones to remove all background colors on any element with .btn class.

html

<button type="button" class="btn btn-outline-primary">Primary</button>
<button type="button" class="btn btn-outline-secondary">Secondary</button>
<button type="button" class="btn btn-outline-success">Success</button>
<button type="button" class="btn btn-outline-danger">Danger</button>
<button type="button" class="btn btn-outline-warning">Warning</button>
<button type="button" class="btn btn-outline-info">Info</button>
<button type="button" class="btn btn-outline-light">Light</button>
<button type="button" class="btn btn-outline-dark">Dark</button>

Some of the button styles use a relatively light foreground color, and should only be used on a dark background in order to have sufficient contrast.

Ghost buttons

Use .btn-ghost-* class for ghost buttons.

html

<button type="button" class="btn btn-ghost-primary">Primary</button>
<button type="button" class="btn btn-ghost-secondary">Secondary</button>
<button type="button" class="btn btn-ghost-success">Success</button>
<button type="button" class="btn btn-ghost-danger">Danger</button>
<button type="button" class="btn btn-ghost-warning">Warning</button>
<button type="button" class="btn btn-ghost-info">Info</button>
<button type="button" class="btn btn-ghost-light">Light</button>
<button type="button" class="btn btn-ghost-dark">Dark</button>

Sizes

Larger or smaller buttons? Add .btn-lg or .btn-sm for additional sizes.

html

<button type="button" class="btn btn-primary btn-lg">Large button</button>
<button type="button" class="btn btn-secondary btn-lg">Large button</button>

html

<button type="button" class="btn btn-primary btn-sm">Small button</button>
<button type="button" class="btn btn-secondary btn-sm">Small button</button>

You can even roll your own custom sizing with CSS variables:

html

<button type="button" class="btn btn-primary"
        style="--cui-btn-padding-y: .25rem; --cui-btn-padding-x: .5rem; --cui-btn-font-size: .75rem;">
  Custom button
</button>

Shapes

Pill buttons

html

<button type="button" class="btn btn-primary rounded-pill">Primary</button>
<button type="button" class="btn btn-secondary rounded-pill">Secondary</button>
<button type="button" class="btn btn-success rounded-pill">Success</button>
<button type="button" class="btn btn-danger rounded-pill">Danger</button>
<button type="button" class="btn btn-warning rounded-pill">Warning</button>
<button type="button" class="btn btn-info rounded-pill">Info</button>
<button type="button" class="btn btn-light rounded-pill">Light</button>
<button type="button" class="btn btn-dark rounded-pill">Dark</button>

Square buttons

html

<button type="button" class="btn btn-primary rounded-0">Primary</button>
<button type="button" class="btn btn-secondary rounded-0">Secondary</button>
<button type="button" class="btn btn-success rounded-0">Success</button>
<button type="button" class="btn btn-danger rounded-0">Danger</button>
<button type="button" class="btn btn-warning rounded-0">Warning</button>
<button type="button" class="btn btn-info rounded-0">Info</button>
<button type="button" class="btn btn-light rounded-0">Light</button>
<button type="button" class="btn btn-dark rounded-0">Dark</button>

Disabled state

Add the disabled boolean attribute to any <button> element to make buttons look inactive. Disabled button has pointer-events: none applied to, disabling hover and active states from triggering.

html

<button type="button" class="btn btn-lg btn-primary" disabled>Primary button</button>
<button type="button" class="btn btn-secondary btn-lg" disabled>Button</button>

Disabled buttons using the <a> element act a little different:

<a>s don’t support the disabled attribute, so you have to add .disabled class to make buttons look inactive. The disabled bootstrap button must have the aria-disabled="true" attribute to show the state of the element to assistive technologies.

Primary link Link

html

<a href="#" class="btn btn-primary btn-lg disabled" tabindex="-1" role="button" aria-disabled="true">Primary link</a>
<a href="#" class="btn btn-secondary btn-lg disabled" tabindex="-1" role="button" aria-disabled="true">Link</a>

Link functionality caveat

To cover cases where you have to keep the href attribute on a disabled link, the .disabled class uses pointer-events: none to try to disable the link functionality of <a>s. Note that this CSS property is not yet standardized for HTML, but all modern browsers support it. In addition, even in browsers that do support pointer-events: none, keyboard navigation remains unaffected, meaning that sighted keyboard users and users of assistive technologies will still be able to activate these links. So to be safe, in addition to aria-disabled="true", also include a tabindex="-1" attribute on these links to prevent them from receiving keyboard focus, and use custom JavaScript to disable their functionality altogether.

Primary link Link

html

<a href="#" class="btn btn-primary btn-lg disabled" tabindex="-1" role="button" aria-disabled="true">Primary link</a>
<a href="#" class="btn btn-secondary btn-lg disabled" tabindex="-1" role="button" aria-disabled="true">Link</a>

Block buttons

Create buttons that span the full width of a parent—by using utilities.

html

<div class="d-grid gap-2">
  <button class="btn btn-primary" type="button">Button</button>
  <button class="btn btn-primary" type="button">Button</button>
</div>

Here we create a responsive variation, starting with vertically stacked buttons until the md breakpoint, where .d-md-block replaces the .d-grid class, thus nullifying the gap-2 utility. Resize your browser to see them change.

html

<div class="d-grid gap-2 d-md-block">
  <button class="btn btn-primary" type="button">Button</button>
  <button class="btn btn-primary" type="button">Button</button>
</div>

You can adjust the width of your block buttons with grid column width classes. For example, for a half-width “block button”, use .col-6. Center it horizontally with .mx-auto, too.

html

<div class="d-grid gap-2 col-6 mx-auto">
  <button class="btn btn-primary" type="button">Button</button>
  <button class="btn btn-primary" type="button">Button</button>
</div>

Additional utilities can be used to adjust the alignment of buttons when horizontal. Here we’ve taken our previous responsive example and added some flex utilities and a margin utility on the button to right align the buttons when they’re no longer stacked.

html

<div class="d-grid gap-2 d-md-flex justify-content-md-end">
  <button class="btn btn-primary me-md-2" type="button">Button</button>
  <button class="btn btn-primary" type="button">Button</button>
</div>

Button plugin

The button plugin allows you to create simple on/off toggle buttons.

Visually, these toggle buttons are identical to the checkbox toggle buttons. However, they are conveyed differently by assistive technologies: the checkbox toggles will be announced by screen readers as “checked”/“not checked” (since, despite their appearance, they are fundamentally still checkboxes), whereas these toggle buttons will be announced as “button”/“button pressed”. The choice between these two approaches will depend on the type of toggle you are creating, and whether or not the toggle will make sense to users when announced as a checkbox or as an actual button.

Toggle states

Add data-coreui-toggle="button" to toggle a button’s active state. If you’re pre-toggling a button, you must manually add the .active class and aria-pressed="true" to the <button>.

html

<p class="d-inline-flex gap-1">
  <button type="button" class="btn" data-coreui-toggle="button">Toggle button</button>
  <button type="button" class="btn active" data-coreui-toggle="button" aria-pressed="true">Active toggle button</button>
  <button type="button" class="btn" disabled data-coreui-toggle="button">Disabled toggle button</button>
</p>
<p class="d-inline-flex gap-1">
  <button type="button" class="btn btn-primary" data-coreui-toggle="button">Toggle button</button>
  <button type="button" class="btn btn-primary active" data-coreui-toggle="button" aria-pressed="true">Active toggle button</button>
  <button type="button" class="btn btn-primary" disabled data-coreui-toggle="button">Disabled toggle button</button>
</p>

Toggle link Active toggle link Disabled toggle link

html

<p class="d-inline-flex gap-1">
  <a href="#" class="btn" role="button" data-coreui-toggle="button">Toggle link</a>
  <a href="#" class="btn active" role="button" data-coreui-toggle="button" aria-pressed="true">Active toggle link</a>
  <a class="btn disabled" aria-disabled="true" role="button" data-coreui-toggle="button">Disabled toggle link</a>
</p>
<p class="d-inline-flex gap-1">
  <a href="#" class="btn btn-primary" role="button" data-coreui-toggle="button">Toggle link</a>
  <a href="#" class="btn btn-primary active" role="button" data-coreui-toggle="button" aria-pressed="true">Active toggle link</a>
  <a class="btn btn-primary disabled" aria-disabled="true" role="button" data-coreui-toggle="button">Disabled toggle link</a>
</p>

Methods

You can create a button instance with the button constructor, for example:

const bsButton = new coreui.Button('#myButton')

Method	Description
`toggle`	Toggles push state. Gives the button the appearance that it has been activated.
`dispose`	Destroys an element’s button. (Removes stored data on the DOM element)
`getInstance`	Static method which allows you to get the button instance associated to a DOM element, you can use it like this: `coreui.Button.getInstance(element)`
`getOrCreateInstance`	Static method which returns a button instance associated to a DOM element or create a new one in case it wasn’t initialized. You can use it like this: `coreui.Button.getOrCreateInstance(element)`

For example, to toggle all buttons

document.querySelectorAll('.btn').forEach(buttonElement => {
  const button = coreui.Button.getOrCreateInstance(buttonElement)
  button.toggle()
})

Customizing

CSS variables

Buttons use local CSS variables on .btn for enhanced real-time customization. Values for the CSS variables are set via Sass, so Sass customization is still supported, too.

scss/_buttons.scss

--#{$prefix}btn-padding-x: #{$btn-padding-x};
--#{$prefix}btn-padding-y: #{$btn-padding-y};
--#{$prefix}btn-font-family: #{$btn-font-family};
@include rfs($btn-font-size, --#{$prefix}btn-font-size);
--#{$prefix}btn-font-weight: #{$btn-font-weight};
--#{$prefix}btn-line-height: #{$btn-line-height};
--#{$prefix}btn-color: #{$btn-color};
--#{$prefix}btn-bg: transparent;
--#{$prefix}btn-border-width: #{$btn-border-width};
--#{$prefix}btn-border-color: transparent;
--#{$prefix}btn-border-radius: #{$btn-border-radius};
--#{$prefix}btn-hover-border-color: transparent;
--#{$prefix}btn-box-shadow: #{$btn-box-shadow};
--#{$prefix}btn-disabled-opacity: #{$btn-disabled-opacity};
--#{$prefix}btn-focus-box-shadow: 0 0 0 #{$btn-focus-width} rgba(var(--#{$prefix}btn-focus-shadow-rgb), .5);

Each .btn-* modifier class updates the appropriate CSS variables to minimize additional CSS rules with our button-variant(), button-outline-variant(), and button-size() mixins.

Here’s an example of building a custom .btn-* modifier class like we do for the buttons unique to our docs by reassigning Bootstrap’s CSS variables with a mixture of our own CSS and Sass variables.

docs/assets/scss/_buttons.scss

.btn-cd-primary {
  --cui-btn-font-weight: 600;
  --cui-btn-color: var(--cui-white);
  --cui-btn-bg: var(--cd-violet-bg);
  --cui-btn-border-color: var(--cd-violet-bg);
  --cui-btn-hover-color: var(--cui-white);
  --cui-btn-hover-bg: #{shade-color($cd-violet, 10%)};
  --cui-btn-hover-border-color: #{shade-color($cd-violet, 10%)};
  --cui-btn-focus-shadow-rgb: var(--cd-violet-rgb);
  --cui-btn-active-color: var(--cui-btn-hover-color);
  --cui-btn-active-bg: #{shade-color($cd-violet, 20%)};
  --cui-btn-active-border-color: #{shade-color($cd-violet, 20%)};
}

SASS variables

scss/_variables.scss

$btn-color:                   var(--#{$prefix}body-color);
$btn-padding-y:               $input-btn-padding-y;
$btn-padding-x:               $input-btn-padding-x;
$btn-font-family:             $input-btn-font-family;
$btn-font-size:               $input-btn-font-size;
$btn-line-height:             $input-btn-line-height;
$btn-white-space:             null; // Set to `nowrap` to prevent text wrapping

$btn-padding-y-sm:            $input-btn-padding-y-sm;
$btn-padding-x-sm:            $input-btn-padding-x-sm;
$btn-font-size-sm:            $input-btn-font-size-sm;

$btn-padding-y-lg:            $input-btn-padding-y-lg;
$btn-padding-x-lg:            $input-btn-padding-x-lg;
$btn-font-size-lg:            $input-btn-font-size-lg;

$btn-border-width:            $input-btn-border-width;

$btn-font-weight:             $font-weight-normal;
$btn-box-shadow:              inset 0 1px 0 rgba($white, .15), 0 1px 1px rgba($black, .075);
$btn-focus-width:             $input-btn-focus-width;
$btn-focus-box-shadow:        $input-btn-focus-box-shadow;
$btn-disabled-opacity:        .65;
$btn-active-box-shadow:       inset 0 3px 5px rgba($black, .125);

$btn-link-color:              var(--#{$prefix}link-color);
$btn-link-hover-color:        var(--#{$prefix}link-hover-color);
$btn-link-disabled-color:     $gray-600;
$btn-link-focus-shadow-rgb:   to-rgb(mix(color-contrast($link-color), $link-color, 15%));

// Allows for customizing button radius independently from global border radius
$btn-border-radius:           var(--#{$prefix}border-radius);
$btn-border-radius-sm:        var(--#{$prefix}border-radius-sm);
$btn-border-radius-lg:        var(--#{$prefix}border-radius-lg);

$btn-transition:              color .15s ease-in-out, background-color .15s ease-in-out, border-color .15s ease-in-out, box-shadow .15s ease-in-out;

$btn-hover-bg-shade-amount:       15%;
$btn-hover-bg-tint-amount:        15%;
$btn-hover-border-shade-amount:   20%;
$btn-hover-border-tint-amount:    10%;
$btn-active-bg-shade-amount:      20%;
$btn-active-bg-tint-amount:       20%;
$btn-active-border-shade-amount:  25%;
$btn-active-border-tint-amount:   10%;

$button-variants: (
  "primary": btn-color-map($primary, $primary),
  "secondary": btn-color-map($secondary, $secondary),
  "success": btn-color-map($success, $success),
  "danger": btn-color-map($danger, $danger),
  "warning": btn-color-map($warning, $warning),
  "info": btn-color-map($info, $info),
  "light": btn-color-map($light, $light),
  "dark": btn-color-map($dark, $dark)
);

$button-outline-ghost-variants: (
  "primary": btn-outline-color-map($primary),
  "secondary": btn-outline-color-map($secondary),
  "success": btn-outline-color-map($success),
  "danger": btn-outline-color-map($danger),
  "warning": btn-outline-color-map($warning),
  "info": btn-outline-color-map($info),
  "light": btn-outline-color-map($light),
  "dark": btn-outline-color-map($dark)
);

SASS variants

CoreUI allows defining variant colors in two ways.

Manual

You can define each color manually and keep full control of the component appearance.

$button-variants: (
  "primary": (
    "background": $your-bg-color,
    "border": $your-border-color,
    "color": $your-color,
    "hover-background": $your-bg-hover-color,
    "hover-border": $your-hover-border-color,
    "hover-color": $your-hover-color,
    "active-background": $your-bg-active-color,
    "active-border": $your-active-border-color,
    "active-color": $your-active-color,
    "disabled-background": $your-bg-disabled-color,,
    "disabled-border": $your-disabled-border-color,
    "disabled-color": $your-disabled-color,
    "shadow": $your-shadow
  )
  ...
);

Color function

The color set can be generated automatically thanks to our button-color-map function.

scss/_functions.scss

@function btn-color($color, $shade, $tint) {
  @return if(color-contrast($color) == $color-contrast-light, shade-color($color, $shade), tint-color($color, $tint));
}

@function btn-color-map($background, $border-color) {
  @return (
    "bg": $background,
    "border-color": $border-color,
    "color": color-contrast($background),
    "hover-bg": btn-color($background, $btn-hover-bg-shade-amount, $btn-hover-bg-tint-amount),
    "hover-border-color": btn-color($border-color, $btn-hover-border-shade-amount, $btn-hover-border-tint-amount),
    "hover-color": color-contrast(btn-color($background, $btn-hover-bg-shade-amount, $btn-hover-bg-tint-amount)),
    "active-bg": btn-color($background, $btn-active-bg-shade-amount, $btn-active-bg-tint-amount),
    "active-border-color": btn-color($border-color, $btn-active-border-shade-amount, $btn-active-border-tint-amount),
    "active-color": color-contrast(btn-color($border-color, $btn-active-border-shade-amount, $btn-active-border-tint-amount)),
    "disabled-bg": $background,
    "disabled-border-color": $border-color,
    "disabled-color": color-contrast($background),
    "shadow": rgba(mix($background, $border-color, 15%), .5)
  );
}

@function btn-outline-color-map($background) {
  @return (
    "color": $background,
    "hover-bg": btn-color($background, $btn-hover-bg-shade-amount, $btn-hover-bg-tint-amount),
    "hover-border-color": btn-color($background, $btn-hover-border-shade-amount, $btn-hover-border-tint-amount),
    "hover-color": color-contrast(btn-color($background, $btn-hover-bg-shade-amount, $btn-hover-bg-tint-amount)),
    "active-bg": btn-color($background, $btn-active-bg-shade-amount, $btn-active-bg-tint-amount),
    "active-border-color": btn-color($background, $btn-active-border-shade-amount, $btn-active-border-tint-amount),
    "active-color": color-contrast(btn-color($background, $btn-active-border-shade-amount, $btn-active-border-tint-amount)),
    "disabled-color": $background,
    "shadow": rgba(mix($background, $background, 15%), .5)
  );
}

$button-variants: (
  "primary": btn-color-map($primary),
  ...
);

–>

SASS mixins

CoreUI’s button component is built with a base-modifier class approach. This means the bulk of the styling is contained to a base class .btn while style variations are confined to modifier classes (e.g., .btn-danger). These modifier classes are built from the $button-variants map to make customizing the number and name of our modifier classes.

There are three mixins for buttons: button and button outline variant mixins, plus a button size mixin.

scss/mixins/_buttons.scss

@mixin button-variant($variant) {
  $background: map-get($variant, "bg");
  $border-color: map-get($variant, "border-color");
  $color: map-get($variant, "color");
  $hover-background: map-get($variant, "hover-bg");
  $hover-border-color: map-get($variant, "hover-border-color");
  $hover-color: map-get($variant, "hover-color");
  $active-background: map-get($variant, "active-bg");
  $active-border-color: map-get($variant, "active-border-color");
  $active-color: map-get($variant, "active-color");
  $disabled-background: map-get($variant, "disabled-bg");
  $disabled-border-color: map-get($variant, "disabled-border-color");
  $disabled-color: map-get($variant, "disabled-color");
  $shadow: map-get($variant, "shadow");

  --#{$prefix}btn-color: #{$color};
  --#{$prefix}btn-bg: #{$background};
  --#{$prefix}btn-border-color: #{$border-color};
  --#{$prefix}btn-hover-color: #{$hover-color};
  --#{$prefix}btn-hover-bg: #{$hover-background};
  --#{$prefix}btn-hover-border-color: #{$hover-border-color};
  --#{$prefix}btn-focus-shadow-rgb: #{to-rgb(mix($color, $border-color, 15%))};
  --#{$prefix}btn-active-color: #{$active-color};
  --#{$prefix}btn-active-bg: #{$active-background};
  --#{$prefix}btn-active-border-color: #{$active-border-color};
  --#{$prefix}btn-active-shadow: #{$btn-active-box-shadow};
  --#{$prefix}btn-disabled-color: #{$disabled-color};
  --#{$prefix}btn-disabled-bg: #{$disabled-background};
  --#{$prefix}btn-disabled-border-color: #{$disabled-border-color};
}

scss/mixins/_buttons.scss

@mixin button-outline-variant($variant) {
  $color: map-get($variant, "color");
  $hover-background: map-get($variant, "hover-bg");
  $hover-border-color: map-get($variant, "hover-border-color");
  $hover-color: map-get($variant, "hover-color");
  $active-background: map-get($variant, "active-bg");
  $active-border-color: map-get($variant, "active-border-color");
  $active-color: map-get($variant, "active-color");
  $disabled-color: map-get($variant, "disabled-color");
  $shadow: map-get($variant, "shadow");

  --#{$prefix}btn-color: #{$color};
  --#{$prefix}btn-border-color: #{$color};
  --#{$prefix}btn-hover-color: #{$hover-color};
  --#{$prefix}btn-hover-bg: #{$active-background};
  --#{$prefix}btn-hover-border-color: #{$active-border-color};
  --#{$prefix}btn-focus-shadow-rgb: #{to-rgb($color)};
  --#{$prefix}btn-active-color: #{$active-color};
  --#{$prefix}btn-active-bg: #{$active-background};
  --#{$prefix}btn-active-border-color: #{$active-border-color};
  --#{$prefix}btn-active-shadow: #{$btn-active-box-shadow};
  --#{$prefix}btn-disabled-color: #{$color};
  --#{$prefix}btn-disabled-bg: transparent;
  --#{$prefix}gradient: none;
}

scss/mixins/_buttons.scss

@mixin button-ghost-variant($variant) {
  $color: map-get($variant, "color");
  $hover-background: map-get($variant, "hover-bg");
  $hover-border-color: map-get($variant, "hover-border-color");
  $hover-color: map-get($variant, "hover-color");
  $active-background: map-get($variant, "active-bg");
  $active-border-color: map-get($variant, "active-border-color");
  $active-color: map-get($variant, "active-color");
  $disabled-color: map-get($variant, "disabled-color");
  $shadow: map-get($variant, "shadow");

  --#{$prefix}btn-color: #{$color};
  --#{$prefix}btn-hover-bg: #{$hover-background};
  --#{$prefix}btn-hover-border-color: #{$hover-border-color};
  --#{$prefix}btn-hover-color: #{$hover-color};
  --#{$prefix}btn-active-bg: #{$active-background};
  --#{$prefix}btn-active-border-color: #{$active-border-color};
  --#{$prefix}btn-active-color: #{$active-color};
  --#{$prefix}btn-disabled-color: #{$disabled-color};
  --#{$prefix}btn-shadow: #{$shadow};
}

scss/mixins/_buttons.scss

@mixin button-size($padding-y, $padding-x, $font-size, $border-radius) {
  --#{$prefix}btn-padding-y: #{$padding-y};
  --#{$prefix}btn-padding-x: #{$padding-x};
  @include rfs($font-size, --#{$prefix}btn-font-size);
  --#{$prefix}btn-border-radius: #{$border-radius};
}

SASS loops

Button variants (for regular and outline buttons) use their respective mixins with our $theme-colors map to generate the modifier classes in scss/_buttons.scss.

scss/_variables.scss

$button-variants: (
  "primary": btn-color-map($primary, $primary),
  "secondary": btn-color-map($secondary, $secondary),
  "success": btn-color-map($success, $success),
  "danger": btn-color-map($danger, $danger),
  "warning": btn-color-map($warning, $warning),
  "info": btn-color-map($info, $info),
  "light": btn-color-map($light, $light),
  "dark": btn-color-map($dark, $dark)
);

$button-outline-ghost-variants: (
  "primary": btn-outline-color-map($primary),
  "secondary": btn-outline-color-map($secondary),
  "success": btn-outline-color-map($success),
  "danger": btn-outline-color-map($danger),
  "warning": btn-outline-color-map($warning),
  "info": btn-outline-color-map($info),
  "light": btn-outline-color-map($light),
  "dark": btn-outline-color-map($dark)
);

scss/_buttons.scss

@each $state, $variant in $button-variants {
  .btn-#{$state} {
    @include button-variant($variant);
  }
}

@each $state, $variant in $button-outline-ghost-variants {
  .btn-outline-#{$state} {
    @include button-outline-variant($variant);
  }
}

@each $state, $variant in $button-outline-ghost-variants {
  .btn-ghost-#{$state} {
    @include button-ghost-variant($variant);
  }
}