JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <section class="sidebar">
    <div class="logo"><a href="#home">&lt;logo&gt;</a></div>
    <nav class="navbar">
      <ul class="nav-links">
        <li><a href="#home">home</a></li>
        <li><a href="#about">about me</a></li>
        <li><a href="#skills">skills</a></li>
        <li><a href="#contact">contact</a></li>
      </ul>
    </nav>
  </section>

  <main class="content-container">
    <section class="home" id="home">
      <h2 id="greet"></h2>
    </section>

    <section class="about" id="about">
      <h2>ABOUT</h2>
      <h3>
        <span>Name</span>
      </h3>
      <p>Lorem ipsum dolor sit amet consectetur adipisicing elit.</p>
    </section>

    <section class="skills" id="skills">
      <h2>SKILLS</h2>
      <h3>Lorem ipsum dolor sit amet.</h3>
      <ul class=tech-skills>
        <li>1</li>
        <li>2</li>
        <li>3</li>
        <li>4</li>
        <li>5</li>
      </ul>
      <h3>Lorem</h3>
      <ul class="languages">
        <li>1</li>
        <li>2</li>
      </ul>
      <h3>Lorem, ipsum.</h3>
      <ul class="learning-skills">
        <li>1</li>
        <li>2</li>
        <li>3</li>
        <li>4</li>
      </ul>
    </section>

    <section class="contact" id="contact">
      <h2>CONTACT</h2>
      <p>handle</p>
      <p>phone</p>
      <p>email</p>
    </section>
  </main>
</div>

CSS

.container {
  display: flex;
  height: 100vh;
}

.sidebar {
  flex: 0 0 25%;
  background-color: #bbbbeb;
  display: flex;
  flex-flow: column;
  padding: 10px;
}

.logo {
  text-align: center;
  font-weight: bold;
}

.navbar {
  margin: auto;
}

.content-container {
  flex: 0 0 75%;
  display: flex;
  flex-flow: column nowrap;
  text-align: center;
  overflow: auto;
  /* height: 100vh */
}

section {
  padding: 10px;
}

.home {
  background-color: red;
  flex: 1;
  min-height: 0; /* new */  
}

.about {
  background-color: orange;
  flex: 1;
  overflow: hidden; /* new */  
}

.skills {
  background-color: orangered;
  flex: 1;
  overflow: auto; /* new */  
}

.contact {
  background-color: crimson;
  flex: 1;
  min-height: 0; /* new */  
}


li {
  list-style: none;
  margin: 10px 0;
  text-align: center;
}

a {
  color: black;
  display: inline-block;
  padding: 2px;
  text-decoration: none;
}

a:hover {
  transform: scale(1.2);
  font-weight: bold;
  border-bottom: 3px solid black;
  text-shadow: 1px 1px 2px rgb(122, 71, 122);
}


* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: 'Comfortaa', sans-serif;
  font-size: 1.4em;
}

JavaScript

var myDate = new Date();
var hrs = myDate.getHours();

var greet;

if (hrs < 12)
  greet = 'Good Morning';
else if (hrs >= 12 && hrs <= 17)
  greet = 'Good Afternoon';
else if (hrs >= 17 && hrs <= 24)
  greet = 'Good Evening';

document.getElementById('greet').innerHTML =
  greet + ', visitor! <br><br> Welcome.';