20150922코딩연습1

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>HTML5</title>
<style>
header {
width:100%;
height:300px;
background-image:url(images/main.jpg);
background-position: center;
}
nav {
    width:100%;
    height: 50px;
    background-color:rgb(0,0,0);
}
nav a {
    padding:0 10px;
    height:50px;
    color:white;
    font-size: 1.7em;
    line-height:50px;
    display:inline-block;
    text-decoration:none;
}
nav a:hover {
    background-color:#f00;
}
body { margin:0; }
.wrap {
    width:1000px;
    margin:0 auto;
}
@media screen and (max-width: 1000px) {
    .wrap { width: 100%; }
    header { background-size:cover; }
}
@media screen and (max-width: 768px) {
    header { height:200px; }
}
@media screen and (max-width: 320px) {
    header { height:100px; }
}
</style>
</head>
<body>
<div class="wrap">
<header id="hdr"></header>
<nav>
<a href="#" onmouseover="bg('food')">HOME</a>
<a href="#" onmouseover="bg('cats')">JavaScript</a>
<a href="#" onmouseover="bg('sports')">CSS</a>
<a href="#" onmouseover="bg('transport')">PHP&amp;MySql</a>
</nav>
</div>
<script>
function bg(c) {
    var src = "images/" + c + ".jpg";
    var h = document.getElementById("hdr");
    var url = "url(" + src + ")";
    h.style.backgroundImage = url;
}
</script>
</body>
</html>