*
{
    box-sizing: border-box;
}
.box 
{
    float: left;
    line-height: 80px;
    background-color: lime;
    border: 1px solid forestgreen;
    border-radius: 5px;
    width: 30%;
    height: 80px;
    text-align: center;
    font-family: Arial;
    color: white;
}
#box2,#box3
{
    margin-left: 5%;
}
#footer 
{
    background-color: lightblue;
    border: 1px solid navy;
    border-radius: 5px;
    padding-top: 20px;
    padding-bottom: 20px;
    text-align: center;
    font-family: Verdana;
    color: white;
    overflow: auto;
    margin-top: auto;
}