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HTML 

              
                <section>
	<h1>Accessible Multi-select Accordion</h1>
	<dl class="accordion">
		<dt>
			<button class="accordion__button" aria-expanded="true" aria-controls="accordion-resources">What resources did you use to build this?</button>
		</dt>
		<dd class="accordion__content" id="accordion-resources" aria-hidden="false">
			<ul>
				<li><a href="https://www.w3.org/TR/wai-aria-practices/#disclosure">Disclosure (FAQ) Design Pattern</a></li>
				<li><a href="https://www.w3.org/TR/wai-aria-practices/examples/disclosure/disclosure-faq.html">Disclosure (FAQ) Example</a></li>
				<li><a href="https://www.w3.org/TR/wai-aria-practices/#accordion">Accordion Design Pattern</a></li>
				<li><a href="https://www.w3.org/TR/wai-aria-practices/examples/accordion/accordion.html">Accordion Example</a></li>
			</ul>
		</dd>

		<dt>
			<button class="accordion__button" aria-expanded="true" aria-controls="accordion-markup">What are the HTML tags and ARIA attributes used?</button>
		</dt>
		<dd class="accordion__content" id="accordion-markup" aria-hidden="false">
			<ul>
				<li><a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/section">section</a></li>
				<li><a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/button">button</a></li>
				<li><a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/dl">dl</a></li>
				<li><a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/dt">dt</a></li>
				<li><a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/dd">dd</a></li>
				<li><a href="https://www.w3.org/TR/wai-aria-1.1/#aria-expanded">aria-expanded</a></li>
				<li><a href="https://www.w3.org/TR/wai-aria-1.1/#aria-controls">aria-controls</a></li>
			</ul>
		</dd>

		<dt>
			<button class="accordion__button" aria-expanded="true" aria-controls="accordion-behavior">What is the expected behavior of this component?</button>
		</dt>
		<dd class="accordion__content" id="accordion-behavior" aria-hidden="false">
			<ul>
				<li>Users can tab to an accordion button which will show focus that button</li>
				<li>When using a keyboard and the NVDA screen reader users can hit Enter or Space to toggle the content for the focused accordion button</li>
				<li>When using the VO screen reader users can navigate to the button with Control + Option + Space</li>
				<li>Then when focused on the button, VO users can toggle the content with Control + Option + Space</li>
			</ul>
		</dd>
	</dl>
</section>
!

CSS 

              
                $theme-primary: #9482ec;
$theme-secondary: #444;

*:focus {
	outline: none;
	box-shadow: 0 0 0 0.125rem #fff, 0 0 0 0.25rem #000;
}

body {
	padding: 1rem 2rem;
	font-family: 'Roboto', sans-serif;
	background-color: #fff;
}

h1 {
	text-align: center;
	margin-bottom: 1.5rem;
	font-family: 'Poppins', sans-serif;
	color: $theme-secondary;
	font-size: 2rem;
}

li {
	margin-bottom: 0.75rem;
}

a {
	padding: 0.25rem 0.125rem 0;
	color: $theme-primary;
	text-decoration: none;
	border-bottom: 1px solid $theme-primary;
	transition: all 150ms ease;

	&:focus,
	&:hover {
		background-color: #cbffd9;
		color: #6a51e7;
		border-bottom: 3px solid #6a51e7;
	}
}

.accordion {
	max-width: 40rem;
	margin: auto;

	&__button {
		text-align: left;
		font-size: 1rem;
		font-family: 'Poppins', sans-serif;
		font-weight: 500;
		background-color: $theme-primary;
		color: #fff;
		border: none;
		padding: 0.5rem 1rem;
		border-radius: 0.25rem;
		display: block;
		width: 100%;
		z-index: 1; // add z-index so focus is always visible
		position: relative;
		margin-top: 1rem;
		transition: all 150ms linear;
		
		&::after {
			content: "";
			display: inline-block;
			position: absolute;
			right: 0.875rem;
			top: 0.875rem;
			width: 0.4rem;
			height: 0.4rem;
			border-right: 0.25rem solid #fff;
			border-top: 0.25rem solid #fff;
			transform: rotate(135deg);
			transition: transform 250ms linear;
		}
		
		&:hover {
			background-color: $theme-secondary;
			transform: scale(1.025);
		}
		
		&[aria-expanded='true'] {
			background-color: $theme-secondary;
		}
		
		&[aria-expanded='true']::after {
			transform: rotate(315deg) translateY(0.25rem);
		}
	}
	
	&__content {
		padding: 0.875rem;
		margin-left: 0;
		background-color: #fff;
		border: 2px solid #eee;
		box-shadow: 1px 4px 10px 1px rgba(0, 0, 0, 0.15);
		transition: all 200ms linear;
		
		&[aria-hidden='false'] {
			display: block;
		}
		
		&[aria-hidden='true'] {
			display: none;
		}
	}
}
!

JS 

              
                const buttons = document.querySelectorAll('.accordion__button');
const contentSections = document.querySelectorAll('.accordion__content');

function setInitialAriaValue(elements, aria, ariaValue) {
	elements.forEach((element) => {
		element.setAttribute(`${aria}`, `${ariaValue}`);
	});
}

function accordionToggleHandler() {
	buttons.forEach((button) => {
		button.addEventListener('click', toggleContent);
	});
}

function toggleContent(e) {
	toggleButton(e.target);
	toggleDetails(e.target);
}

function toggleButton(button) {
	const expandedValue = button.getAttribute('aria-expanded');
	const setValue = expandedValue === 'true' ? 'false' : 'true';
	button.setAttribute('aria-expanded', setValue);
}

function toggleDetails(button) {
	const buttonAriaControl = button.getAttribute('aria-controls');
	const content = document.getElementById(buttonAriaControl);
  const hiddenValue = content.getAttribute('aria-hidden');
	const setValue = hiddenValue === 'true' ? 'false' : 'true';
	content.setAttribute('aria-hidden', setValue);
}

setInitialAriaValue(buttons, 'aria-expanded', 'false');
setInitialAriaValue(contentSections, 'aria-hidden', 'true');
accordionToggleHandler();
!
999px

Console