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HTML

CSS

CSS Base

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Add External Stylesheets/Pens

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JavaScript

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Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

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HTML

              
                <nav class="main-nav">
  <a href="#"><img src="https://upload.wikimedia.org/wikipedia/commons/thumb/2/2f/Logo_TV_2015.svg/1200px-Logo_TV_2015.svg.png" alt="logo"></a>
</nav>
<section>
  <h1>Title</h1>
  <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Ducimus quas nam, fugit mollitia quasi aspernatur, ipsa incidunt perspiciatis, aliquam doloribus minus iusto enim voluptatem quos dolores minima sit odio natus dolorem ullam! Inventore, obcaecati odio. Earum, excepturi amet? Voluptas dolorem doloremque fugit sit porro iure consequatur dolore obcaecati minus cupiditate?</p>
</section>
<section>
  <h1>Title</h1>
  <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Ducimus quas nam, fugit mollitia quasi aspernatur, ipsa incidunt perspiciatis, aliquam doloribus minus iusto enim voluptatem quos dolores minima sit odio natus dolorem ullam! Inventore, obcaecati odio. Earum, excepturi amet? Voluptas dolorem doloremque fugit sit porro iure consequatur dolore obcaecati minus cupiditate?</p>
</section>
<section>
  <h1>Title</h1>
  <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Ducimus quas nam, fugit mollitia quasi aspernatur, ipsa incidunt perspiciatis, aliquam doloribus minus iusto enim voluptatem quos dolores minima sit odio natus dolorem ullam! Inventore, obcaecati odio. Earum, excepturi amet? Voluptas dolorem doloremque fugit sit porro iure consequatur dolore obcaecati minus cupiditate?</p>
</section>
<section>
  <h1>Title</h1>
  <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Ducimus quas nam, fugit mollitia quasi aspernatur, ipsa incidunt perspiciatis, aliquam doloribus minus iusto enim voluptatem quos dolores minima sit odio natus dolorem ullam! Inventore, obcaecati odio. Earum, excepturi amet? Voluptas dolorem doloremque fugit sit porro iure consequatur dolore obcaecati minus cupiditate?</p>
</section>
<section>
  <h1>Title</h1>
  <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Ducimus quas nam, fugit mollitia quasi aspernatur, ipsa incidunt perspiciatis, aliquam doloribus minus iusto enim voluptatem quos dolores minima sit odio natus dolorem ullam! Inventore, obcaecati odio. Earum, excepturi amet? Voluptas dolorem doloremque fugit sit porro iure consequatur dolore obcaecati minus cupiditate?</p>
</section>
              
            
!

CSS

              
                

* {
  box-sizing: border-box;
}
html {
  margin: 0;
}
body {
  margin-top: 120px;
}
.main-nav{
  position: fixed;
  top: 0;
  height: 100px;
  width: 100%;
  border-bottom: 1px solid #ccc;
  padding: 10px 20px;
  background-color: #fff6f6; 
  transition: all 300ms ease-in-out;
}
.small {
  height: 40px;
}
.main-nav img{
  height: 100%;
  width: auto;
}
section {
  width: 600px;
  margin: 100px auto;
}
              
            
!

JS

              
                let nav = document.querySelector('.main-nav');

window.addEventListener('scroll', function(){
  if(window.pageYOffset > 100) {
    nav.classList += ' small'
  } else {
    nav.classList = 'main-nav';
  }
})
              
            
!
999px

Console