Tryit Editor v2.0

Code:
<!DOCTYPE html>
<html>
<head>
<style>
button
{
position:absolute;
}

button#b1
{
top:20%;left:25%;
nav-index:1;
nav-right:#b2; nav-left:#b4;
nav-down:#b2; nav-up:#b4;
}

button#b2
{
top:40%;left:50%;
nav-index:2;
nav-right:#b3; nav-left:#b1;
nav-down:#b3; nav-up:#b1;
}

button#b3
{
top:70%;left:25%;
nav-index:3;
nav-right:#b4; nav-left:#b2;
nav-down:#b4; nav-up:#b2;
}

button#b4
{
top:40%;left:0%;
nav-index:4;
nav-right:#b1; nav-left:#b3;
nav-down:#b1; nav-up:#b3;
}
</style>
</head>
<body>

<button id="b1">Button 1</button>
<button id="b2">Button 2</button>
<button id="b3">Button 3</button>
<button id="b4">Button 4</button>

<p><b>Note:</b> The nav- properties are currently supported only in Opera. Hold down the Shift key while navigating with the arrow keys.</p>

</body>
</html>