Remove highlight from active button

Question

I have a couple of buttons styled as tabs for an options menu. Everything looks like I want and it's working fine. The only problem I have is the blue highlight on the active button. How can I remove it?

For reasons I don't understand, my code snippet does not reproduce the problem.

function ShowCurrent()
{
	document.getElementById('btnCurrent').className = "menu";
	document.getElementById('btnFuture').className = "menu off";
}

function ShowFuture()
{
	document.getElementById('btnFuture').className = "menu";
	document.getElementById('btnCurrent').className = "menu off";
}

.menu
{
	border: 2px solid grey;
	border-bottom: none;
	margin-bottom: -2px;
	margin-right: 5px;
	padding: 3px 2px;
	position: relative;
	z-index: 5;
}

.off
{
	border-bottom: 2px solid grey;
	padding: 2px;
}

.placeholder
{
    border: 2px solid grey;
}

<div>
	<button id="btnCurrent" class="menu" onClick="ShowCurrent();">Current</button>
	<button id="btnFuture" class="menu off" onClick="ShowFuture();">Future</button>
</div>

<div class="placeholder">Just hanging out, taking up space</div>

Answer 1

Just add outline:0

function ShowCurrent() {
  document.getElementById('btnCurrent').className = "menu";
  document.getElementById('btnFuture').className = "menu off";
}

function ShowFuture() {
  document.getElementById('btnFuture').className = "menu";
  document.getElementById('btnCurrent').className = "menu off";
}

button.menu {
  border: 2px solid grey;
  border-bottom: none;
  margin-bottom: -2px;
  margin-right: 5px;
  padding: 3px 2px;
  position: relative;
  z-index: 5;
  outline: 0;
}
button.off {
  border-bottom: 2px solid grey;
  padding: 2px;
}
.placeholder {
  border: 2px solid grey;
}

<div>
  <button id="btnCurrent" class="menu" onClick="ShowCurrent();">Current</button>
  <button id="btnFuture" class="menu off" onClick="ShowFuture();">Future</button>
</div>

<div class="placeholder">Just hanging out, taking up space</div>