底部滚动条(Bottom scrollbar)

 我有一个问题。为什么我得到这个底部滚动条？不能真正理解。我知道我可以删除它，但我甚至不知道为什么它apears。 需要Hlp。 https://codepen.io/anon/pen/oBjqxr 
 
 -HTML 
 
<nav role="navigation">
  <div id="menuToggle">
    <!--
    A fake / hidden checkbox is used as click reciever,
    so you can use the :checked selector on it.
    -->
    <input type="checkbox" />

    <!--
    Some spans to act as a hamburger.

    They are acting like a real hamburger,
    not that McDonalds stuff.
    -->
    <span></span>
    <span></span>
    <span></span>

    <!--
    Too bad the menu has to be inside of the button
    but hey, it's pure CSS magic.
    -->
    <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>
 
 -CSS 
 
body
{
  margin: 0;
  padding: 0;

  /* make it look decent enough */
  background: #232323;
  color: #cdcdcd;
  font-family: "Avenir Next", "Avenir", sans-serif;
}

a
{
  text-decoration: none;
  color: #232323;

  transition: color 0.3s ease;
}

a:hover
{
  color: tomato;
}

#menuToggle
{
  display: block;
  position: relative;
  top: 50px;
  left: 50px;

  z-index: 1;

  -webkit-user-select: none;
  user-select: none;
}

#menuToggle input
{
  display: block;
  width: 40px;
  height: 32px;
  position: absolute;
  top: -7px;
  left: -5px;

  cursor: pointer;

  opacity: 0; /* hide this */
  z-index: 2; /* and place it over the hamburger */

  -webkit-touch-callout: none;
}

/*
 * Just a quick hamburger
 */
#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%;
}

/* 
 * Transform all the slices of hamburger
 * into a crossmark.
 */
#menuToggle input:checked ~ span
{
  opacity: 1;
  transform: rotate(45deg) translate(-2px, -1px);
  background: #232323;
}

/*
 * But let's hide the middle one.
 */
#menuToggle input:checked ~ span:nth-last-child(3)
{
  opacity: 0;
  transform: rotate(0deg) scale(0.2, 0.2);
}

/*
 * Ohyeah and the last one should go the other direction
 */
#menuToggle input:checked ~ span:nth-last-child(2)
{
  opacity: 1;
  transform: rotate(-45deg) translate(0, -1px);
}

/*
 * Make this absolute positioned
 * at the top left of the screen
 */
#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;
  /* to stop flickering of text in safari */

  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;
}

/*
 * And let's fade it in from the left
 */
#menuToggle input:checked ~ ul
{
  transform: scale(1.0, 1.0);
  opacity: 1;
}

i have a question.Why am i getting this bottom scrollbar?Cant really understand.I know that i can remove it but i cant even understand why it apears. Hlp needed. https://codepen.io/anon/pen/oBjqxr
 
-HTML
 
<nav role="navigation">
  <div id="menuToggle">
    <!--
    A fake / hidden checkbox is used as click reciever,
    so you can use the :checked selector on it.
    -->
    <input type="checkbox" />

    <!--
    Some spans to act as a hamburger.

    They are acting like a real hamburger,
    not that McDonalds stuff.
    -->
    <span></span>
    <span></span>
    <span></span>

    <!--
    Too bad the menu has to be inside of the button
    but hey, it's pure CSS magic.
    -->
    <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>
 
-CSS
 
body
{
  margin: 0;
  padding: 0;

  /* make it look decent enough */
  background: #232323;
  color: #cdcdcd;
  font-family: "Avenir Next", "Avenir", sans-serif;
}

a
{
  text-decoration: none;
  color: #232323;

  transition: color 0.3s ease;
}

a:hover
{
  color: tomato;
}

#menuToggle
{
  display: block;
  position: relative;
  top: 50px;
  left: 50px;

  z-index: 1;

  -webkit-user-select: none;
  user-select: none;
}

#menuToggle input
{
  display: block;
  width: 40px;
  height: 32px;
  position: absolute;
  top: -7px;
  left: -5px;

  cursor: pointer;

  opacity: 0; /* hide this */
  z-index: 2; /* and place it over the hamburger */

  -webkit-touch-callout: none;
}

/*
 * Just a quick hamburger
 */
#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%;
}

/* 
 * Transform all the slices of hamburger
 * into a crossmark.
 */
#menuToggle input:checked ~ span
{
  opacity: 1;
  transform: rotate(45deg) translate(-2px, -1px);
  background: #232323;
}

/*
 * But let's hide the middle one.
 */
#menuToggle input:checked ~ span:nth-last-child(3)
{
  opacity: 0;
  transform: rotate(0deg) scale(0.2, 0.2);
}

/*
 * Ohyeah and the last one should go the other direction
 */
#menuToggle input:checked ~ span:nth-last-child(2)
{
  opacity: 1;
  transform: rotate(-45deg) translate(0, -1px);
}

/*
 * Make this absolute positioned
 * at the top left of the screen
 */
#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;
  /* to stop flickering of text in safari */

  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;
}

/*
 * And let's fade it in from the left
 */
#menuToggle input:checked ~ ul
{
  transform: scale(1.0, 1.0);
  opacity: 1;
}

原文：https://stackoverflow.com/questions/41552978