Accordion

Bootstrap 5 Accordion component

Responsive accordion built with the latest Bootstrap 5. Accordion is a vertically collapsing element to show and hide content via class changes.

Build vertically collapsing accordions in combination with our Collapse JavaScript plugin.

How it works

The accordion uses collapse internally to make it collapsible. To render an accordion that’s expanded, add the .show class on the .accordion-collapse.

Required ES init: Collapse *
* UMD autoinits are enabled by default. This means that you don't need to initialize the component manually. However if you are using MDBootstrap ES format then you should pass the required components to the initMDB method.

Basic example

Click the accordions below to expand/collapse the accordion content.

This is the first item's accordion body. It is shown by default, until the collapse plugin adds the appropriate classes that we use to style each element. These classes control the overall appearance, as well as the showing and hiding via CSS transitions. You can modify any of this with custom CSS or overriding our default variables. It's also worth noting that just about any HTML can go within the .accordion-body, though the transition does limit overflow.

This is the second item's accordion body. It is hidden by default, until the collapse plugin adds the appropriate classes that we use to style each element. These classes control the overall appearance, as well as the showing and hiding via CSS transitions. You can modify any of this with custom CSS or overriding our default variables. It's also worth noting that just about any HTML can go within the .accordion-body, though the transition does limit overflow.

This is the third item's accordion body. It is hidden by default, until the collapse plugin adds the appropriate classes that we use to style each element. These classes control the overall appearance, as well as the showing and hiding via CSS transitions. You can modify any of this with custom CSS or overriding our default variables. It's also worth noting that just about any HTML can go within the .accordion-body, though the transition does limit overflow.
Edit in sandbox 
<div class="accordion" id="accordionExample">
  <div class="accordion-item">
    <h2 class="accordion-header" id="headingOne">
      <button
        data-mdb-collapse-init
        class="accordion-button"
        type="button"
        data-mdb-target="#collapseOne"
        aria-expanded="true"
        aria-controls="collapseOne"
      >
        Accordion Item #1
      </button>
    </h2>
    <div id="collapseOne" class="accordion-collapse collapse show" aria-labelledby="headingOne" data-mdb-parent="#accordionExample">
      <div class="accordion-body">
        <strong>This is the first item's accordion body.</strong> It is hidden by default,
        until the collapse plugin adds the appropriate classes that we use to style each
        element. These classes control the overall appearance, as well as the showing and
        hiding via CSS transitions. You can modify any of this with custom CSS or
        overriding our default variables. It's also worth noting that just about any HTML
        can go within the <strong>.accordion-body</strong>, though the transition does
        limit overflow.
      </div>
    </div>
  </div>
  <div class="accordion-item">
    <h2 class="accordion-header" id="headingTwo">
      <button
        data-mdb-collapse-init
        class="accordion-button collapsed"
        type="button"
        data-mdb-target="#collapseTwo"
        aria-expanded="false"
        aria-controls="collapseTwo"
      >
        Accordion Item #2
      </button>
    </h2>
    <div id="collapseTwo" class="accordion-collapse collapse" aria-labelledby="headingTwo" data-mdb-parent="#accordionExample">
      <div class="accordion-body">
        <strong>This is the second item's accordion body.</strong> It is hidden by
        default, until the collapse plugin adds the appropriate classes that we use to
        style each element. These classes control the overall appearance, as well as the
        showing and hiding via CSS transitions. You can modify any of this with custom CSS
        or overriding our default variables. It's also worth noting that just about any
        HTML can go within the <strong>.accordion-body</strong>, though the transition
        does limit overflow.
      </div>
    </div>
  </div>
  <div class="accordion-item">
    <h2 class="accordion-header" id="headingThree">
      <button
        data-mdb-collapse-init
        class="accordion-button collapsed"
        type="button"
        data-mdb-target="#collapseThree"
        aria-expanded="false"
        aria-controls="collapseThree"
      >
        Accordion Item #3
      </button>
    </h2>
    <div id="collapseThree" class="accordion-collapse collapse" aria-labelledby="headingThree" data-mdb-parent="#accordionExample">
      <div class="accordion-body">
        <strong>This is the third item's accordion body.</strong> It is hidden by default,
        until the collapse plugin adds the appropriate classes that we use to style each
        element. These classes control the overall appearance, as well as the showing and
        hiding via CSS transitions. You can modify any of this with custom CSS or
        overriding our default variables. It's also worth noting that just about any HTML
        can go within the <strong>.accordion-body</strong>, though the transition does
        limit overflow.
      </div>
    </div>
  </div>
</div>
// Initialization for ES Users
import { Collapse, initMDB } from 'mdb-ui-kit';

initMDB({ Collapse });

Flush

Add .accordion-flush to remove the default background-color, some borders, and some rounded corners to render accordions edge-to-edge with their parent container.

Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor, sunt aliqua put a bird on it squid single-origin coffee nulla assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat craft beer farm-to-table, raw denim aesthetic synth nesciunt you probably haven't heard of them accusamus labore sustainable VHS.

Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor, sunt aliqua put a bird on it squid single-origin coffee nulla assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat craft beer farm-to-table, raw denim aesthetic synth nesciunt you probably haven't heard of them accusamus labore sustainable VHS.

Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor, sunt aliqua put a bird on it squid single-origin coffee nulla assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat craft beer farm-to-table, raw denim aesthetic synth nesciunt you probably haven't heard of them accusamus labore sustainable VHS.
Edit in sandbox 
<div class="accordion accordion-flush" id="accordionFlushExample">
  <div class="accordion-item">
    <h2 class="accordion-header" id="flush-headingOne">
      <button
        data-mdb-collapse-init
        class="accordion-button collapsed"
        type="button"
        data-mdb-target="#flush-collapseOne"
        aria-expanded="false"
        aria-controls="flush-collapseOne"
      >
        Accordion Item #1
      </button>
    </h2>
    <div
      id="flush-collapseOne"
      class="accordion-collapse collapse"
      aria-labelledby="flush-headingOne"
      data-mdb-parent="#accordionFlushExample"
    >
      <div class="accordion-body">
        Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry
        richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor
        brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor,
        sunt aliqua put a bird on it squid single-origin coffee nulla assumenda shoreditch
        et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt
        sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat
        craft beer farm-to-table, raw denim aesthetic synth nesciunt you probably haven't
        heard of them accusamus labore sustainable VHS.
      </div>
    </div>
  </div>
  <div class="accordion-item">
    <h2 class="accordion-header" id="flush-headingTwo">
      <button
        data-mdb-collapse-init
        class="accordion-button collapsed"
        type="button"
        data-mdb-target="#flush-collapseTwo"
        aria-expanded="false"
        aria-controls="flush-collapseTwo"
      >
        Accordion Item #2
      </button>
    </h2>
    <div
      id="flush-collapseTwo"
      class="accordion-collapse collapse"
      aria-labelledby="flush-headingTwo"
      data-mdb-parent="#accordionFlushExample"
    >
      <div class="accordion-body">
        Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry
        richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor
        brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor,
        sunt aliqua put a bird on it squid single-origin coffee nulla assumenda shoreditch
        et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt
        sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat
        craft beer farm-to-table, raw denim aesthetic synth nesciunt you probably haven't
        heard of them accusamus labore sustainable VHS.
      </div>
    </div>
  </div>
  <div class="accordion-item">
    <h2 class="accordion-header" id="flush-headingThree">
      <button
        data-mdb-collapse-init
        class="accordion-button collapsed"
        type="button"
        data-mdb-target="#flush-collapseThree"
        aria-expanded="false"
        aria-controls="flush-collapseThree"
      >
        Accordion Item #3
      </button>
    </h2>
    <div
      id="flush-collapseThree"
      class="accordion-collapse collapse"
      aria-labelledby="flush-headingThree"
      data-mdb-parent="#accordionFlushExample"
    >
      <div class="accordion-body">
        Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry
        richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor
        brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor,
        sunt aliqua put a bird on it squid single-origin coffee nulla assumenda shoreditch
        et. Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt
        sapiente ea proident. Ad vegan excepteur butcher vice lomo. Leggings occaecat
        craft beer farm-to-table, raw denim aesthetic synth nesciunt you probably haven't
        heard of them accusamus labore sustainable VHS.
      </div>
    </div>
  </div>
</div>
// Initialization for ES Users
import { Collapse, initMDB } from 'mdb-ui-kit';

initMDB({ Collapse });

Borderless

Add .accordion-borderless to remove all the borders and add a background color to the active item.

Placeholder content for this accordion, which is intended to demonstrate the .accordion-flush class. This is the first item's accordion body.

Placeholder content for this accordion, which is intended to demonstrate the .accordion-flush class. This is the second item's accordion body. Let's imagine this being filled with some actual content.

Placeholder content for this accordion, which is intended to demonstrate the .accordion-flush class. This is the third item's accordion body. Nothing more exciting happening here in terms of content, but just filling up the space to make it look, at least at first glance, a bit more representative of how this would look in a real-world application.
Edit in sandbox 
<div class="accordion accordion-borderless" id="accordionFlushExampleX">
  <div class="accordion-item">
    <h2 class="accordion-header" id="flush-headingOneX">
      <button data-mdb-collapse-init class="accordion-button" type="button"
        data-mdb-target="#flush-collapseOneX" aria-expanded="true" aria-controls="flush-collapseOneX">
        Accordion Item #1
      </button>
    </h2>
    <div id="flush-collapseOneX" class="accordion-collapse collapse show"
      aria-labelledby="flush-headingOneX" data-mdb-parent="#accordionFlushExampleX">
      <div class="accordion-body">
        Placeholder content for this accordion, which is intended to demonstrate the
        <code>.accordion-flush</code> class. This is the first item's accordion body.
      </div>
    </div>
  </div>
  <div class="accordion-item">
    <h2 class="accordion-header" id="flush-headingTwoX">
      <button data-mdb-collapse-init class="accordion-button collapsed" type="button"
        data-mdb-target="#flush-collapseTwoX" aria-expanded="false" aria-controls="flush-collapseTwoX">
        Accordion Item #2
      </button>
    </h2>
    <div id="flush-collapseTwoX" class="accordion-collapse collapse" aria-labelledby="flush-headingTwoX"
      data-mdb-parent="#accordionFlushExampleX">
      <div class="accordion-body">
        Placeholder content for this accordion, which is intended to demonstrate the
        <code>.accordion-flush</code> class. This is the second item's accordion body.
        Let's imagine this being filled with some actual content.
      </div>
    </div>
  </div>
  <div class="accordion-item">
    <h2 class="accordion-header" id="flush-headingThreeX">
      <button data-mdb-collapse-init class="accordion-button collapsed" type="button"
        data-mdb-target="#flush-collapseThreeX" aria-expanded="false" aria-controls="flush-collapseThreeX">
        Accordion Item #3
      </button>
    </h2>
    <div id="flush-collapseThreeX" class="accordion-collapse collapse" aria-labelledby="flush-headingThreeX"
      data-mdb-parent="#accordionFlushExampleX">
      <div class="accordion-body">
        Placeholder content for this accordion, which is intended to demonstrate the
        <code>.accordion-flush</code> class. This is the third item's accordion body.
        Nothing more exciting happening here in terms of content, but just filling up
        the space to make it look, at least at first glance, a bit more representative
        of how this would look in a real-world application.
      </div>
    </div>
  </div>
</div>
// Initialization for ES Users
import { Collapse, initMDB } from 'mdb-ui-kit';

initMDB({ Collapse });

With icons

You can easily add icons to the header of the accordion. Read icons docs to see all the available icons.

This is the first item's accordion body. It is hidden by default, until the collapse plugin adds the appropriate classes that we use to style each element. These classes control the overall appearance, as well as the showing and hiding via CSS transitions. You can modify any of this with custom CSS or overriding our default variables. It's also worth noting that just about any HTML can go within the .accordion-body, though the transition does limit overflow.

This is the second item's accordion body. It is hidden by default, until the collapse plugin adds the appropriate classes that we use to style each element. These classes control the overall appearance, as well as the showing and hiding via CSS transitions. You can modify any of this with custom CSS or overriding our default variables. It's also worth noting that just about any HTML can go within the .accordion-body, though the transition does limit overflow.

This is the third item's accordion body. It is hidden by default, until the collapse plugin adds the appropriate classes that we use to style each element. These classes control the overall appearance, as well as the showing and hiding via CSS transitions. You can modify any of this with custom CSS or overriding our default variables. It's also worth noting that just about any HTML can go within the .accordion-body, though the transition does limit overflow.
Edit in sandbox 
<div class="accordion" id="accordionExampleY">
  <div class="accordion-item">
    <h2 class="accordion-header" id="headingOneY">
      <button data-mdb-collapse-init class="accordion-button" type="button"
        data-mdb-target="#collapseOneY" aria-expanded="true" aria-controls="collapseOneY">
        <i class="fas fa-question-circle fa-sm me-2 opacity-70"></i>Accordion Item #1
      </button>
    </h2>
    <div id="collapseOneY" class="accordion-collapse collapse show" aria-labelledby="headingOneY"
      data-mdb-parent="#accordionExampleY">
      <div class="accordion-body">
        <strong>This is the first item's accordion body.</strong> It is hidden by
        default, until the collapse plugin adds the appropriate classes that we use to
        style each element. These classes control the overall appearance, as well as
        the showing and hiding via CSS transitions. You can modify any of this with
        custom CSS or overriding our default variables. It's also worth noting that
        just about any HTML can go within the <code>.accordion-body</code>, though the
        transition does limit overflow.
      </div>
    </div>
  </div>
  <div class="accordion-item">
    <h2 class="accordion-header" id="headingTwoY">
      <button data-mdb-collapse-init class="accordion-button collapsed" type="button"
        data-mdb-target="#collapseTwoY" aria-expanded="false" aria-controls="collapseTwoY">
        <i class="fas fa-question-circle fa-sm me-2 opacity-70"></i>Accordion Item #2
      </button>
    </h2>
    <div id="collapseTwoY" class="accordion-collapse collapse" aria-labelledby="headingTwoY"
      data-mdb-parent="#accordionExampleY">
      <div class="accordion-body">
        <strong>This is the second item's accordion body.</strong> It is hidden by
        default, until the collapse plugin adds the appropriate classes that we use to
        style each element. These classes control the overall appearance, as well as
        the showing and hiding via CSS transitions. You can modify any of this with
        custom CSS or overriding our default variables. It's also worth noting that
        just about any HTML can go within the <code>.accordion-body</code>, though the
        transition does limit overflow.
      </div>
    </div>
  </div>
  <div class="accordion-item">
    <h2 class="accordion-header" id="headingThreeY">
      <button data-mdb-collapse-init class="accordion-button collapsed" type="button"
        data-mdb-target="#collapseThreeY" aria-expanded="false" aria-controls="collapseThreeY">
        <i class="fas fa-question-circle fa-sm me-2 opacity-70"></i>Accordion Item #3
      </button>
    </h2>
    <div id="collapseThreeY" class="accordion-collapse collapse" aria-labelledby="headingThreeY"
      data-mdb-parent="#accordionExampleY">
      <div class="accordion-body">
        <strong>This is the third item's accordion body.</strong> It is hidden by
        default, until the collapse plugin adds the appropriate classes that we use to
        style each element. These classes control the overall appearance, as well as
        the showing and hiding via CSS transitions. You can modify any of this with
        custom CSS or overriding our default variables. It's also worth noting that
        just about any HTML can go within the <code>.accordion-body</code>, though the
        transition does limit overflow.
      </div>
    </div>
  </div>
</div>
// Initialization for ES Users
import { Collapse, initMDB } from 'mdb-ui-kit';

initMDB({ Collapse });

Always open

Omit the data-mdb-parent attribute on each .accordion-collapse to make accordion items stay open when another item is opened.

This is the first item's accordion body. It is shown by default, until the collapse plugin adds the appropriate classes that we use to style each element. These classes control the overall appearance, as well as the showing and hiding via CSS transitions. You can modify any of this with custom CSS or overriding our default variables. It's also worth noting that just about any HTML can go within the .accordion-body, though the transition does limit overflow.

This is the second item's accordion body. It is hidden by default, until the collapse plugin adds the appropriate classes that we use to style each element. These classes control the overall appearance, as well as the showing and hiding via CSS transitions. You can modify any of this with custom CSS or overriding our default variables. It's also worth noting that just about any HTML can go within the .accordion-body, though the transition does limit overflow.

This is the third item's accordion body. It is hidden by default, until the collapse plugin adds the appropriate classes that we use to style each element. These classes control the overall appearance, as well as the showing and hiding via CSS transitions. You can modify any of this with custom CSS or overriding our default variables. It's also worth noting that just about any HTML can go within the .accordion-body, though the transition does limit overflow.
Edit in sandbox 
<div class="accordion" id="accordionPanelsStayOpenExample">
  <div class="accordion-item">
    <h2 class="accordion-header" id="headingOne">
      <button data-mdb-collapse-init class="accordion-button" type="button"
        data-mdb-target="#panelsStayOpen-collapseOne" aria-expanded="true" aria-controls="panelsStayOpen-collapseOne">
        Accordion Item #1
      </button>
    </h2>
    <div id="panelsStayOpen-collapseOne" class="accordion-collapse collapse show" aria-labelledby="headingOne">
      <div class="accordion-body">
        <strong>This is the first item's accordion body.</strong> It is shown by default,
        until the collapse plugin adds the appropriate classes that we use to style each
        element. These classes control the overall appearance, as well as the showing and
        hiding via CSS transitions. You can modify any of this with custom CSS or overriding
        our default variables. It's also worth noting that just about any HTML can go within
        the <code>.accordion-body</code>, though the transition does limit overflow.
      </div>
    </div>
  </div>
  <div class="accordion-item">
    <h2 class="accordion-header" id="headingTwo">
      <button data-mdb-collapse-init class="accordion-button collapsed" type="button"
        data-mdb-target="#panelsStayOpen-collapseTwo" aria-expanded="false"
        aria-controls="panelsStayOpen-collapseTwo">
        Accordion Item #2
      </button>
    </h2>
    <div id="panelsStayOpen-collapseTwo" class="accordion-collapse collapse" aria-labelledby="headingTwo">
      <div class="accordion-body">
        <strong>This is the second item's accordion body.</strong> It is hidden by default,
        until the collapse plugin adds the appropriate classes that we use to style each
        element. These classes control the overall appearance, as well as the showing and
        hiding via CSS transitions. You can modify any of this with custom CSS or overriding
        our default variables. It's also worth noting that just about any HTML can go within
        the <code>.accordion-body</code>, though the transition does limit overflow.
      </div>
    </div>
  </div>
  <div class="accordion-item">
    <h2 class="accordion-header" id="headingThree">
      <button data-mdb-collapse-init class="accordion-button collapsed" type="button"
        data-mdb-target="#panelsStayOpen-collapseThree" aria-expanded="false"
        aria-controls="panelsStayOpen-collapseThree">
        Accordion Item #3
      </button>
    </h2>
    <div id="panelsStayOpen-collapseThree" class="accordion-collapse collapse" aria-labelledby="headingThree">
      <div class="accordion-body">
        <strong>This is the third item's accordion body.</strong> It is hidden by default,
        until the collapse plugin adds the appropriate classes that we use to style each
        element. These classes control the overall appearance, as well as the showing and
        hiding via CSS transitions. You can modify any of this with custom CSS or overriding
        our default variables. It's also worth noting that just about any HTML can go within
        the <code>.accordion-body</code>, though the transition does limit overflow.
      </div>
    </div>
  </div>
</div>
// Initialization for ES Users
import { Collapse, initMDB } from 'mdb-ui-kit';

initMDB({ Collapse });

Accessibility

Please read the collapse accessibility section for more information.

Accordion - API

Import

Importing components depends on how your application works. If you intend to use the MDBootstrap ES format, you must first import the component and then initialize it with the initMDB method. If you are going to use the UMD format, just import the mdb-ui-kit package.

Edit in sandbox 
import { Collapse, initMDB } from "mdb-ui-kit";

initMDB({ Collapse });
import "mdb-ui-kit"

Usage

Via data attributes

Using the Accordion component doesn't require any additional JavaScript code - simply add data-mdb-collapse-init attribute to every .accordion-button and use other data attributes to set all options. For ES format, you must first import and call the initMDB method.

Edit in sandbox 
<div class="accordion" id="accordionPanelsStayOpenExample">
  <div class="accordion-item">
    <h2 class="accordion-header" id="headingOne">
      <button
        data-mdb-collapse-init
        class="accordion-button"
        type="button"
        data-mdb-toggle="collapse"
        data-mdb-target="#panelsStayOpen-collapseOne"
        aria-expanded="true"
        aria-controls="panelsStayOpen-collapseOne"
      >
        Accordion Item #1
      </button>
    </h2>
    <div
      id="panelsStayOpen-collapseOne"
      class="accordion-collapse collapse show"
      aria-labelledby="headingOne"
    >
      <div class="accordion-body">...</div>
    </div>
  </div>
  <div class="accordion-item">
    <h2 class="accordion-header" id="headingTwo">
      <button
        data-mdb-collapse-init
        class="accordion-button collapsed"
        type="button"
        data-mdb-toggle="collapse"
        data-mdb-target="#panelsStayOpen-collapseTwo"
        aria-expanded="false"
        aria-controls="panelsStayOpen-collapseTwo"
      >
        Accordion Item #2
      </button>
    </h2>
    <div
      id="panelsStayOpen-collapseTwo"
      class="accordion-collapse collapse"
      aria-labelledby="headingTwo"
    >
      <div class="accordion-body">...</div>
    </div>
  </div>
  <div class="accordion-item">
    <h2 class="accordion-header" id="headingThree">
      <button
        data-mdb-collapse-init
        class="accordion-button collapsed"
        type="button"
        data-mdb-toggle="collapse"
        data-mdb-target="#panelsStayOpen-collapseThree"
        aria-expanded="false"
        aria-controls="panelsStayOpen-collapseThree"
      >
        Accordion Item #3
      </button>
    </h2>
    <div
      id="panelsStayOpen-collapseThree"
      class="accordion-collapse collapse"
      aria-labelledby="headingThree"
    >
      <div class="accordion-body">...</div>
    </div>
  </div>
</div>

Via JavaScript

Edit in sandbox 
const element = document.querySelector('.accordion')
const instance = new Collapse(element)
const element = document.querySelector('.accordion')
const instance = new mdb.Collapse(element)

CSS variables

As part of MDB’s evolving CSS variables approach, accordion now uses local CSS variables on .accordion for enhanced real-time customization. Values for the CSS variables are set via Sass, so Sass customization is still supported, too.

Edit in sandbox 
// .accordion
--#{$prefix}accordion-color: #{$accordion-color};
--#{$prefix}accordion-bg: #{$accordion-bg};
--#{$prefix}accordion-transition: #{$accordion-transition};
--#{$prefix}accordion-border-color: #{$accordion-border-color};
--#{$prefix}accordion-border-width: #{$accordion-border-width};
--#{$prefix}accordion-border-radius: #{$accordion-border-radius};
--#{$prefix}accordion-inner-border-radius: #{$accordion-inner-border-radius};
--#{$prefix}accordion-btn-padding-x: #{$accordion-button-padding-x};
--#{$prefix}accordion-btn-padding-y: #{$accordion-button-padding-y};
--#{$prefix}accordion-btn-color: #{$accordion-button-color};
--#{$prefix}accordion-btn-bg: #{$accordion-button-bg};
--#{$prefix}accordion-btn-icon: #{escape-svg($accordion-button-icon)};
--#{$prefix}accordion-btn-icon-width: #{$accordion-icon-width};
--#{$prefix}accordion-btn-icon-transform: #{$accordion-icon-transform};
--#{$prefix}accordion-btn-icon-transition: #{$accordion-icon-transition};
--#{$prefix}accordion-btn-active-icon: #{escape-svg($accordion-button-active-icon)};
--#{$prefix}accordion-btn-focus-border-color: #{$accordion-button-focus-border-color};
--#{$prefix}accordion-btn-focus-box-shadow: #{$accordion-button-focus-box-shadow};
--#{$prefix}accordion-body-padding-x: #{$accordion-body-padding-x};
--#{$prefix}accordion-body-padding-y: #{$accordion-body-padding-y};
--#{$prefix}accordion-active-color: #{$accordion-button-active-color};
--#{$prefix}accordion-active-bg: #{$accordion-button-active-bg};

// .accordion-flush
--#{$prefix}accordion-flush-btn-box-shadow: #{$accordion-flush-button-box-shadow};
--#{$prefix}accordion-flush-border-bottom: #{$accordion-flush-item-border-bottom};

// .accordion-borderless
--#{$prefix}accordion-borderless-btn-border-radius: #{$accordion-borderless-button-border-radius};
--#{$prefix}accordion-borderless-btn-bg: #{$accordion-borderless-button-bgc};
--#{$prefix}accordion-borderless-btn-color: #{$accordion-borderless-button-color};

SCSS variables

Edit in sandbox 
$accordion-padding-y: 1.15rem;
$accordion-padding-x: 1.5rem;
$accordion-color: var(--#{$prefix}surface-color);
$accordion-bg: var(--#{$prefix}body-bg);
$accordion-border-width: var(--#{$prefix}border-width);
$accordion-border-color: var(--#{$prefix}border-color);
$accordion-border-radius: $border-radius-lg;
$accordion-inner-border-radius: subtract(
  $accordion-border-radius,
  $accordion-border-width
);

$accordion-body-padding-y: $accordion-padding-y;
$accordion-body-padding-x: $accordion-padding-x;

$accordion-button-padding-y: $accordion-padding-y;
$accordion-button-padding-x: $accordion-padding-x;
$accordion-button-color: var(--#{$prefix}surface-color);
$accordion-button-bg: var(--#{$prefix}accordion-bg);
$accordion-transition: $btn-transition, border-radius 0.15s ease;
$accordion-button-active-bg: var(--#{$prefix}surface-bg);
$accordion-button-active-color: $primary;

$accordion-button-focus-border-color: $input-focus-border-color;
$accordion-button-focus-box-shadow: inset 0 -1px 0 var(--#{$prefix}border-color);

$accordion-icon-width: 1.25rem;
$accordion-icon-color: $surface-color;;
$accordion-icon-active-color: $primary;
$accordion-icon-transition: transform 0.2s ease-in-out;
$accordion-icon-transform: rotate(-180deg);

$accordion-button-icon: url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16' fill='none' stroke='#{$accordion-icon-color}' stroke-linecap='round' stroke-linejoin='round'><path d='M2 5L8 11L14 5'/></svg>");
$accordion-button-active-icon: url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16' fill='none' stroke='#{$accordion-icon-active-color}' stroke-linecap='round' stroke-linejoin='round'><path d='M2 5L8 11L14 5'/></svg>");

$accordion-flush-button-box-shadow: inset 0 -2px 0 var(--#{$prefix}divider-color);
$accordion-flush-item-border-bottom: 2px solid var(--#{$prefix}divider-color);
$accordion-borderless-button-border-radius: 0.5rem;
$accordion-borderless-button-bgc: var(--#{$prefix}primary-bg-subtle);
$accordion-borderless-button-color: var(--#{$prefix}primary-text-emphasis);