*{
    padding: 0;
    margin:0;
    box-sizing: border-box;
}

body{
    font-family: Arial, Helvetica, sans-serif;
min-height: 100vh;
    display: flex;
    flex-direction: column;
}   

header{
    flex: 0 0 60px;
    background-color: #333;
    color: #fff;
    padding: 20px;
    text-align: center;
}
main{
    flex: 1;
    flex-basis: calc(100vh - 120px)
}


footer{
    flex: 0 0 60px;
    background-color: #505050;
    color: #fff;
    padding: 20px;
    text-align: center;
}