JSFiddle - React, Tailwind, and code Playground

HTML

<div class="menu"></div>
<div class="footer">
  out <br/>
  of <br/>
  the <br/>
  flow <br/>
</div>

CSS

html, body {
  height: 100%;
}

/* styling .menu is just decor */
.menu {
  height: 100%;
  background-color: rgba(200, 20, 20, .2);
}

.footer {
  position: fixed;
  bottom: 0;
  width: 100%;
  /* next line is just decor */
  background-color: rgba(20, 200, 20, .2);
}