webservices-app/src/lib/components/CollapsibleSection.svelte

<script>
    // Ref: https://svelte.dev/repl/a5f4d395b15a44d48a6b2239ef705fc4?version=3.35.0
    // based on suggestions from:
    // Inclusive Components by Heydon Pickering https://inclusive-components.design/collapsible-sections/
    export let headerText;

    let expanded = false
</script>

<div class="collapsible">
    <h3>
        <button aria-expanded={expanded} on:click={() => expanded = !expanded}>{headerText}
            <svg viewBox="0 0 20 20" fill="none" >
                <path class="vert" d="M10 1V19" stroke="black" stroke-width="2"/>
                <path d="M1 10L19 10" stroke="black" stroke-width="2"/>
            </svg>
        </button>
    </h3>

    <div class='contents' hidden={!expanded}>
        <slot></slot>
    </div>
</div>

<style>
  .collapsible {
    border-bottom: 1px solid var(--gray-light, #eee);
	color: #eee !important;
	background-color: #666 !important;
  }
  h3 { margin: 0; }
  button {
    background-color: var(--background, #fff);
    color: var(--gray-darkest, #282828);
    display: flex;
    justify-content: space-between;
    /*width: 100%;*/
	border: none;
	margin: 0;
	padding: 1em 0.5em;
  }
  button[aria-expanded="true"] { border-bottom: 1px solid var(--gray-light, #eee); }
  button[aria-expanded="true"] .vert { display: none; }
  button:focus svg { outline: 2px solid; }
  button[aria-expanded="true"] rect { fill: currentColor; }
  svg { height: 0.7em; width: 0.7em; }
</style>