Getting something aligned at the bottom of the screen is always a pain in the rear with CSS. Try putting something like this in the stylesheet of your theme:
html, body {
height: 100%;
text-align: center;
}
.qa-body-wrapper {
display: inline-block;
min-height: 100%;
}
.qa-footer {
position: fixed;
box-sizing: border-box;
bottom: 0;
left: 0;
width: 100%;
}
Further adjustments may be required.