JSFiddle - React, Tailwind, and code Playground

HTML

<main>
  <div id="myClippetWrapper">
    <div id="clippetNav"></div>
    <div id="codeAndNotesWrapper">
      <div id="codeView"></div>
      <div id="noteView">
        <div id="codeNotesEditor"></div>
      </div>
    </div>
  </div>
</main>

CSS

main {
  max-width: 50%;
  margin: 10px auto;
  padding: 8px;
  background-color: red;
}

#myClippetWrapper {
  display: flex;
  height: 700px;
}

#clippetNav {
  display: flex;
  padding: 10px;
  width: 250px;
  margin-right: 10px;
  background-color: #222222;
}

#codeAndNotesWrapper {
  display: flex;
  width: 100%;
}

#codeAndNotesWrapper>div {
  display: flex;
  flex-basis: 100%;
}

#codeView {
  display: flex;
  padding: 10px;
  margin-right: 10px;
  background-color: #222222;
}

#noteView {
  display: flex;
  flex-direction: column;
  padding: 10px;
  background-color: #222222;
}

#codeNotesEditor {
  flex: 1;
  background-color: #EAEAEA;
}