box-sizing doesn't works on li with inline-block

I don't know why, but only on my footer with li in inline-block and border-top on active class, my box-sizing : border-box doesn't work.

When the class is active, there are a border-top, and we see a gap on the bottom.

Here an exemple :

* { box-sizing: border-box }
#header{
	position:absolute;
	top:0;
	right:0;
	left:0;
	background-color:#333c45;
	height:60px;
	line-height:60px; 
}
#corp{
	position:absolute;
	top:60px;
	bottom:60px;
	right:0;
	left:0;
	background-color:#CDCDCD;
}
#footer{
	position:absolute;
	bottom:0;
	right:0;
	left:0;
	background-color:#333c45;
	height:60px;
	line-height:60px;
		
}
#footer li{
	display:inline-block;
	width:45%;
}
ul{
	margin:0;
	padding:0;
}
.active{
	color:#05FF01;
	border-top:2px solid #05FF01;
}

<html>
<head>
</head>
<body>
<div id="header">
test 
</div>
<div id="corp">
</div>
<div id="footer">
<ul>
<li class="active">boutton 1</li>
<li>boutton 2</li>
</ul>
</div>
</body>
</html>

How can I solve this problem ?

Thank you !

Solution

Add overflow:hidden to the body. It will prevent any vertical scrollbar.

Also, as a side note, IMO making a layout with every element in position:absolute is a terrible idea and you'll quickly get headaches.

* {
  box-sizing: border-box
}

body {
  overflow: hidden;
}

#header {
  position: absolute;
  top: 0;
  right: 0;
  left: 0;
  background-color: #333c45;
  height: 60px;
  line-height: 60px;
}

#corp {
  position: absolute;
  top: 60px;
  bottom: 60px;
  right: 0;
  left: 0;
  background-color: #CDCDCD;
}

#footer {
  position: absolute;
  bottom: 0;
  right: 0;
  left: 0;
  background-color: #333c45;
  height: 60px;
  line-height: 60px;
}

#footer li {
  display: inline-block;
  width: 45%;
}

ul {
  margin: 0;
  padding: 0;
}

.active {
  color: #05FF01;
  border-top: 2px solid #05FF01;
}

<html>

<head>
</head>

<body>
  <div id="header">
    test
  </div>
  <div id="corp">
  </div>
  <div id="footer">
    <ul>
      <li class="active">boutton 1</li>
      <li>boutton 2</li>
    </ul>
  </div>
</body>

</html>