Background-size-contain

Codice
<style>
.contain-box {
width: 400px;
height: 250px;
background-image: url('Algoritmo.jpg');
background-repeat: no-repeat;
background-position: center;
background-size: contain;
border: 1px solid #333;
}
</style>
</head>
<body>
<a href="#" onClick="window.history.go(-1);">Home</a>
<div class="contain-box"></div>