JSFiddle - React, Tailwind, and code Playground

HTML

<html>
<head>
</head>
<body>
  <div class="page">
    <div class="page">
      <div class="sidebar">
        <button>
          haha
        </button>
        <button>
          haha
        </button>
        <button>
          haha
        </button>
      </div>
      <div class="content">
        <div class="step-content">
          whatever
          <div>
            <table>
              <thead>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
                  <th>hahahaha</th>
              </thead>
              <tbody>
                <tr>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                  <td>hahahaha</td>
                </tr>
                
              </tbody>
            </table>
    ...

CSS

.page {
  width: 100%;
  height: 100%;
  display: flex;
}

.sidebar {
  flex: 0.15;
  background-color: red;
}

.content {
  flex: 0.85;
  background-color: blue;
  display: flex;
  flex-direction: column;
  text-align: center;
}

.step-content {
  flex: 1;
}

.step-footer {
  display: block;
  
}
table {
  display: block;
  overflow-x: auto;
  white-space: nowrap;
}
button {
  display: block;
}