I’m using a pure CSS collapsible environment from this link: https://www.digitalocean.com/community/tutorials/css-collapsible. It worked great for years, but suddenly all of my collapsible elements are un-collapsed by default and they include a visible checkbox, which didn’t used to be the case.

Here’s an example of the HTML:

<div class="wrap-collapsible">
  <input id="eg1" class="toggle" type="checkbox">
  <label for="eg2" class="lbl-toggle">First label</label>
  <div class="collapsible-content">
    <div class="content-inner">
    <p>Initial content</p>
    </div>
  </div>
  <input id="eg2" class="toggle" type="checkbox">
  <label for="eg2" class="lbl-toggle">Fancy label</label>
  <div class="collapsible-content">
    <div class="content-inner">
    <p>Some content</p>
    <p>More content</p>
    </div>
  </div>
</div>

And here’s the CSS:

.wrap-collapsible {
  margin-bottom: 1.2rem 0;
}

input[type='checkbox'] {
  display: none;
}

.lbl-toggle {
  /*display: block;
  font-size: 8ppx;*/
  text-align: left;

  padding: -10px;

  /*color: black;*/
  background: white;

  cursor: pointer;

  border-radius: 7px;
  transition: all 0.25s ease-out;
}

.lbl-toggle:hover {
  color: grey;
}

.lbl-toggle::before {
  content: ' ';
  display: inline-block;

  border-top: 5px solid transparent;
  border-bottom: 5px solid transparent;
  border-left: 5px solid currentColor;

  vertical-align: middle;
  margin-right: .7rem;
  transform: translateY(-2px);

  transition: transform .2s ease-out;
}

.collapsible-content .content-inner {
  /*background: rgba(250, 224, 66, .2);
  border-bottom: 1px solid rgba(250, 224, 66, .45);*/

  border-bottom-left-radius: 7px;
  border-bottom-right-radius: 7px;
  padding: 0rem 0rem 0rem 2rem;
}

.collapsible-content {
  max-height: 0px;
  overflow: hidden;

  transition: max-height .25s ease-in-out;
}

.toggle:checked + .lbl-toggle + .collapsible-content {
  max-height: 350px;
}

.toggle:checked + .lbl-toggle::before {
  transform: rotate(90deg) translateX(-3px);
}

.toggle:checked + .lbl-toggle {
  border-bottom-right-radius: 0;
  border-bottom-left-radius: 0;
}

I don’t know a ton of CSS or HTML, so I haven’t tried anything to fix it.