close checkbox hamburger menu, when clicked outside without javascript/jquery possibly

i have hamburger menu which i took from here. https://codepen.io/erikterwan/pen/EVzeRP it is using only css by using a checkbox to expand and collapse the menu.

so what i want is when i click outside the menu (anywhere on the page), the menu should collapse. can someone help me.

this is the html code

<nav role="navigation">
  <div id="menuToggle">

    <input type="checkbox" />
    
    <span></span>
    <span></span>
    <span></span>
    
    <ul id="menu">
      <a href="#"><li>Home</li></a>
      <a href="#"><li>About</li></a>
      <a href="#"><li>Info</li></a>
      <a href="#"><li>Contact</li></a>
      <a href="https://erikterwan.com/" target="_blank"><li>Show me more</li></a>
    </ul>
  </div>
</nav>

this is the css code

body
{
  margin: 0;
  padding: 0;
  
  background: #232323;
  color: #cdcdcd;
  font-family: "Avenir Next", "Avenir", sans-serif;
}

#menuToggle
{
  display: block;
  position: relative;
  top: 50px;
  left: 50px;
  
  z-index: 1;
  
  -webkit-user-select: none;
  user-select: none;
}

#menuToggle a
{
  text-decoration: none;
  color: #232323;
  
  transition: color 0.3s ease;
}

#menuToggle a:hover
{
  color: tomato;
}


#menuToggle input
{
  display: block;
  width: 40px;
  height: 32px;
  position: absolute;
  top: -7px;
  left: -5px;
  
  cursor: pointer;
  
  opacity: 0; 
  z-index: 2; 
  
  -webkit-touch-callout: none;
}

#menuToggle span
{
  display: block;
  width: 33px;
  height: 4px;
  margin-bottom: 5px;
  position: relative;
  
  background: #cdcdcd;
  border-radius: 3px;
  
  z-index: 1;
  
  transform-origin: 4px 0px;
  
  transition: transform 0.5s cubic-bezier(0.77,0.2,0.05,1.0),
              background 0.5s cubic-bezier(0.77,0.2,0.05,1.0),
              opacity 0.55s ease;
}

#menuToggle span:first-child
{
  transform-origin: 0% 0%;
}

#menuToggle span:nth-last-child(2)
{
  transform-origin: 0% 100%;
}

#menuToggle input:checked ~ span
{
  opacity: 1;
  transform: rotate(45deg) translate(-2px, -1px);
  background: #232323;
}

#menuToggle input:checked ~ span:nth-last-child(3)
{
  opacity: 0;
  transform: rotate(0deg) scale(0.2, 0.2);
}

#menuToggle input:checked ~ span:nth-last-child(2)
{
  transform: rotate(-45deg) translate(0, -1px);
}

#menu
{
  position: absolute;
  width: 300px;
  margin: -100px 0 0 -50px;
  padding: 50px;
  padding-top: 125px;
  
  background: #ededed;
  list-style-type: none;
  -webkit-font-smoothing: antialiased;

  
  transform-origin: 0% 0%;
  transform: translate(-100%, 0);
  
  transition: transform 0.5s cubic-bezier(0.77,0.2,0.05,1.0);
}

#menu li
{
  padding: 10px 0;
  font-size: 22px;
}

#menuToggle input:checked ~ ul
{
  transform: none;
}