JSFiddle - React, Tailwind, and code Playground

HTML

<body>
	 <div class="container">
        <div class="sidebarcontainer">
            <div class="innersidebarcontainer">
                    <div class="sidebar">
                    <div class="test1"></div>
                    <div class="test2"></div>
                </div>
            </div>
        </div><!--
    --><div class="mainpage">
        <div class="page"></div>
    </div> 
    </div>
    <div class="footer"></div>
</body>

CSS

.container{
  width: 100%;
  background-color: #d5d5d5;
}
.sidebarcontainer{
  width: 300PX;
  height: 2000px;
  display: inline-block;
  box-sizing: border-box;
  padding: 5px;
  padding-right: 2px;
}
.innersidebarcontainer{
  position: relative;
      width: 100%;
    height: 100%;
}
.sidebar{
  width: 293px;
  background-color: white;
  height: 700px;
  top: 1px;
  position: absolute;
}
.mainpage{
  width: calc(100% - 300px);
  padding: 5px;
  padding-right: 2px;
  height: 3000px;
  display: inline-block;
  box-sizing: border-box;
  background-color: teal;
}
.page{
  width: 100%;
  width: 100%;
  background-color: white;
}
.footer{
  height: 500px;
  width: 100%;
  margin: 0 auto;
  background-color: purple
}
.test1{
  background-color: red;
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  height: 200px;
}
.test2{
  background-color: red;
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 200px;
}