<!DOCTYPE html>
<html>
<head>
<title>overlay div</title>
<style>
body{
position: relative;
padding: 20px;
margin:0;
min-height:100%;
font-family: 'Open Sans', sans-serif;
background: #8ebf42;
color: #eeeeee;
}
.overlay {
position: absolute;
top: 0;
left: 0;
height: 100%;
width: 100%;
z-index: 10;
background-color: rgba(0,0,0,0.6);
}
.modal {
width: 300px;
height: 200px;
line-height: 200px;
position: fixed;
top: 40%;
left: 50%;
margin-top: -100px;
margin-left: -150px;
background-color: #8ebf42;
border-radius: 40px;
text-align: center;
z-index: 11;