dropdowns

by ShaCP

HTML

<body>
    <div id="main-container">
      <div id="overlay" class="hidden"></div>
      <div role="button" tabindex="0" class="section">
        <h3>Some<br />text</h3>
      </div>
      <div class="collapsible hidden">Hidden</div>
      <div role="button" tabindex="0" class="section">
        <h3>Some<br />text</h3>
      </div>
      <div class="collapsible hidden">Hidden</div>
    </div>
    <button>
      Overlay
    </button>
  </body>

CSS

body {
  font-family: sans-serif;
  box-sizing: border-box;
  font-size: 2em;
}

#main-container {
  border: 1px solid black;
  display: inline-block;
  position: relative;
  min-width: 500px;
}

.section {
  text-align: center;
  margin: 10px 0;
  display: flex;
  justify-content: center;
  padding-right: 1em;
}

.section::before {
  content: "";
  background-image: url("https://upload.wikimedia.org/wikipedia/commons/2/24/TriangleArrow-Right.svg");
  background-size: 1em 1em;
  width: 1em;
  height: 1em;
  display: inline-block;
  align-self: center;
  justify-content: left;
  margin-left: 0.1em;
}

.down::before {
  transform: rotate(90deg);
}

h3 {
  flex: auto;
}

@media screen and (max-width: 1024px) {
  #main-container {
    width: 100%;
    box-sizing: border-box;
  }
}

#overlay {
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  background-color: grey;
  opacity: 75%;
  position: absolute;
  z-index: 1;
}

.hidden {
  display: none;
}

button {
  margin: 10px 0;
  display: block;
}

.collapsible {
  text-align: center;
}
body {
  font-family: sans-serif;
  box-sizing: border-box;
  font-size: 2em;
}

#main-container {
  border: 1px solid black;
  display: inline-block;
  position: relative;
  min-width: 500px;
}

.section {
  text-align: center;
  margin: 10px 0;
  display: flex;
  justify-content: center;
  padding-right: 1em;
}

.section::before {
  content: "";
  background-image: url("https://upload.wikimedia.org/wikipedia/commons/2/24/TriangleArrow-Right.svg");
  background-size: 1em 1em;
  width: 1em;
  height: 1em;
  display: inline-block;
  align-self: center;
  justify-content: left;
  margin-left: 0.1em;
}

.down::before {
  transform: rotate(90deg);
}

h3 {
  flex: auto;
}

@media screen and (max-width: 1024px) {
  #main-container {
    width: 100%;
    box-sizing: border-box;
  }
}

#overlay {
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  background-color: grey;
  opacity: 75%;
  position: absolute;
  z-index: 1;
}

.hidden {
  display:...

JavaScript

function show(evt) {
  overlay.classList.toggle("hidden");
}
const overlay = document.querySelector("#overlay");
document.querySelector("button").addEventListener("click", show);
const div = document.querySelectorAll(".section");
div.forEach(d =>
  d.addEventListener("click", evt => {
    evt.currentTarget.classList.toggle("down");
    evt.currentTarget.nextElementSibling.classList.toggle("hidden");
  })
);