How to make use of it:

1. Add titles and content to the accordion interface.

<div id="accordion" class="accordion-container">
  <h4 class="accordion-title">Accordion Title1</h4>
  <div class="accordion-content">
    <p>Accordion Content1</p>
  </div>
  <h4 class="accordion-title">Accordion Title2</h4>
  <div class="accordion-content">
    <p>Accordion Content2</p>
  </div>
  <h4 class="accordion-title">Accordion Title3</h4>
  <div class="accordion-content">
    <p>Accordion Content3</p>
  </div>
</div>

2. This accordion menu requires the newest jQuery library.

<script src="/path/to/cdn/jquery.min.js"></script>

3. Hide the accordion panels on the web page load.

$(".accordion-content").css("display", "none");

4. Enable the accordion titles to toggle their corresponding accordion panels on click on them.

$(".accordion-title").click(function () {
  $(".accordion-title").not(this).removeClass("open");
  $(".accordion-title").not(this).next().slideUp(300);
  $(this).toggleClass("open");
  $(this).next().slideToggle(300);
});

5. The essential CSS styles for the accordion menu.

.accordion-container .accordion-title {
  position: relative;
  margin: 0;
  padding: 0.625em 0.625em 0.625em 2em;
  background-color: #000;
  font-size: 1.25em;
  font-weight: normal;
  color: #fff;
  cursor: pointer;
}

.accordion-container .accordion-title:hover,
.accordion-container .accordion-title:active,
.accordion-title.open { 
  background-color: #00aaa7;
}

.accordion-container .accordion-title::before {
  content: "";
  position: absolute;
  top: 50%;
  right: 25px;
  width: 15px;
  height: 2px;
  transform: rotate(90deg);
  background: #fff;
  transition: all .3s ease-in-out;
}

.accordion-container .accordion-title::after {
  content: "";
  position: absolute;
  top: 50%;
  right: 25px;
  width: 15px;
  height: 2px;
  background: #fff;
  transition: all .2s ease-in-out;
}

.accordion-container .accordion-title.open::before {
  transform: rotate(180deg);
}

.accordion-container .accordion-title.open::after {
  opacity: 0;
}

.accordion-content {
  padding-left: 2.3125em;
  border: 1px solid #0079c1;
}