body {
    display: flex;
    flex-direction: column;
}
main {
    flex: 1;
    min-height: 90vh;
}
/* .footer {
    bottom: 0;
    width: 100%;
    height: auto; 
    line-height: auto; 
    background-color: #f5f5f5;
    padding: 18px 0 18px 0;
} */