How to create a collapsible section with CSS and JavaScript.

A Collapsible Section makes a section, or group of fields, collapsible. It is useful when there are several sections in your form and you want them to take up less vertical space.

Create A Collapsible Section

Step 1) Add HTML

Example Code:

<button type="button" class="collapsible">Open Collapsible</button>
<div class="content">
  <p>Lorem ipsum...</p>
</div>

Step 2) Add CSS
Style the accordion:

Example Code:

/* Style the button that is used to open and close the collapsible content */
.collapsible {
  background-color: #eee;
  color: #444;
  cursor: pointer;
  padding: 18px;
  width: 100%;
  border: none;
  text-align: left;
  outline: none;
  font-size: 15px;
}

/* Add a background color to the button if it is clicked on (add the .active class with JS), and when you move the mouse over it (hover) */
.active, .collapsible:hover {
  background-color: #ccc;
}

/* Style the collapsible content. Note: hidden by default */
.content {
  padding: 0 18px;
  display: none;
  overflow: hidden;
  background-color: #f1f1f1;
}

Step 3) Add JavaScript:

Example Code:

var coll = document.getElementsByClassName("collapsible");
var i;

for (i = 0; i < coll.length; i++) {
  coll[i].addEventListener("click", function() {
    this.classList.toggle("active");
    var content = this.nextElementSibling;
    if (content.style.display === "block") {
      content.style.display = "none";
    } else {
      content.style.display = "block";
    }
  });
}

Add Icons
Add a symbol to each button to indicate whether the collapsible content is open or closed:

Example Code:

.collapsible:after {
  content: '\02795'; /* Unicode character for "plus" sign (+) */
  font-size: 13px;
  color: white;
  float: right;
  margin-left: 5px;
}

.active:after {
  content: "\2796"; /* Unicode character for "minus" sign (-) */
}