flexbox-sticky-footer-fix.css

.layout
{
    display: -webkit-box;
    display: -webkit-flex;
    display: -ms-flexbox;
    display: flex;
    -webkit-box-orient: vertical;
    -webkit-box-direction: normal;
    -webkit-flex-direction: column;
    -ms-flex-direction: column;
    flex-direction: column;
    height: 100%;
}

.header,
.footer
{
    -webkit-box-flex: 0;
    -webkit-flex: none;
    -ms-flex: none;
    flex: none;
}

.content
{
    -webkit-box-flex: 1;
    -webkit-flex: 1 0 auto;
    -ms-flex: 1 0 auto;
    flex: 1 0 auto;
    padding: 1.5em 1.5em 0;
    width: 100%;
}