JSFiddle - React, Tailwind, and code Playground

HTML

<div class="header">
  Header ---> Scroll to Right
  <div class="slideMenu">
    Menu is visible offscreen- :(
  </div>
</div>

CSS

html,
body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
}

.header {
  width: 100%;
  padding: 10px;
  background: #CCC;
  position: relative;
}

.slideMenu {
  position: absolute;
  top: 100%;
  left: 100%;
  width: 100%;
  padding: 10px;
  background: #666;
}