<div class="container">
  <nav class="navbar">
      <ul>
          <li><a href="#home">Home</a></li>
          <li><a href="#about">About</a></li>
          <li><a href="#service">Service</a></li>
          <li><a href="#contact">Contact</a></li>
        </ul>
      </nav>
  <section id="home">
    <h1>Welcome To My Site</h1>
    <p class="lead">Lorem ipsum dolor sit, amet consectetur adipisicing elit. Commodi, quis!</p>
  </section>
  <section id="about">
      <h1>About</h1>
      <p class="lead">Lorem ipsum dolor sit, amet consectetur adipisicing elit. Commodi, quis!</p>
  </section>
  <section id="service">
      <h1>Service</h1>
      <p class="lead">Lorem ipsum dolor sit, amet consectetur adipisicing elit. Commodi, quis!</p>
  </section>
  <section id="contact">
      <h1>Contact</h1>
      <p class="lead">Lorem ipsum dolor sit, amet consectetur adipisicing elit. Commodi, quis!</p>
  </section>
</div>
* {
  margin: 0;
  padding: 0;
}

body {
  font-family: Arial, Helvetica, sans-serif;
  background: #333;
  color: #fff;
  height: 100vh;
  line-height: 1.6;
  overflow: hidden;
}

.container {
  width: 100%;
  height: 100%;
  /* CSS Smooth Scroll */
  overflow-y: scroll; 
  scroll-behavior: smooth;
  scroll-snap-type: y mandatory;
}

.lead {
  font-size: 1.5rem;
}

.navbar {
  position: fixed;
  top: 0;
  z-index: 1;
  display: flex;
  width: 100%;
  height: 60px;
  background: rgba(0,0,0,0.7);
}

.navbar ul {
  display: flex;
  list-style: none;
  width: 100%;
  justify-content: center;
}

.navbar ul li {
  margin: 0 1rem;
  padding: 1rem;
}

.navbar ul li a {
  text-decoration: none;
  text-transform: uppercase;
  color: #f4f4f4;
}

.navbar ul li a:hover {
  color: skyblue;
}

section {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  width: 100%;
  height: 100vh;
 
  /* Scroll Snap */
  scroll-snap-align: center;
}

section h1 {
  font-size: 4rem;
}

/* Section Images */
section#home {
  background: url('https://source.unsplash.com/bZZp1PmHI0E/1600x900') no-repeat center center/cover;;
}

section#about {
  background: url('https://source.unsplash.com/VRxo0yY-gyM/1600x900') no-repeat center center/cover;;
}

section#service {
  background: url('https://source.unsplash.com/K2tdx2mFDHc/1600x900') no-repeat center center/cover;;
}

section#contact {
  background: url('https://source.unsplash.com/2aAHlfDOhJM/1600x900') no-repeat center center/cover;;
}
// Option 2 - jQuery Smooth Scrolling
// $('.navbar a').on('click', function (e) {
//   if (this.hash !== '') {
//     e.preventDefault();

//     const hash = this.hash;

//     $('html, body')
//       .animate({
//         scrollTop: $(hash).offset().top
//       },800);
//   }
// });


 // Option 3 - Smooth Scroll - https://github.com/cferdinandi/smooth-scroll
//  const scroll = new SmoothScroll('.navbar a[href*="#"]', {
// 	speed: 500
// });
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External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js
  2. https://cdn.jsdelivr.net/gh/cferdinandi/smooth-scroll/dist/smooth-scroll.polyfills.min.js