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Adding Classes

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About the <head>

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Insecure Resource

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CSS

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CSS preprocessors help make authoring CSS easier. All of them offer things like variables and mixins to provide convenient abstractions.

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CSS Base

About CSS Base

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JavaScript

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JavaScript preprocessors can help make authoring JavaScript easier and more convenient.

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Babel includes JSX processing.

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HTML 

              
                <div class="container">
  <div class="sections">
    <div class="section active" data-bgcolor="#364652">
      <h2 class="section--header">Bronte, Australia</h2>
      <div class="section--image"><img src="https://images.unsplash.com/photo-1532275948649-7d97f309ef16?ixlib=rb-0.3.5&ixid=eyJhcHBfaWQiOjEyMDd9&s=db3d266a0c1ec46b95f03a271a78603f&auto=format&fit=crop&w=2250&q=80" /></div>
    </div>
    <div class="section" data-bgcolor="#C1A5A9">
      <h2 class="section--header">Kénitra, Morocco</h2>
      <div class="section--image"><img src="https://images.unsplash.com/photo-1532173311168-91e999ce4e47?ixlib=rb-0.3.5&ixid=eyJhcHBfaWQiOjEyMDd9&s=cf6ff267733890306ca709fa2184dd3a&auto=format&fit=crop&w=1301&q=80" /></div>
    </div>
    <div class="section" data-bgcolor="#4ECDC4">
      <h2 class="section--header">Black Mountain, CA</h2>
      <div class="section--image"><img src="https://images.unsplash.com/photo-1532275948649-7d97f309ef16?ixlib=rb-0.3.5&ixid=eyJhcHBfaWQiOjEyMDd9&s=db3d266a0c1ec46b95f03a271a78603f&auto=format&fit=crop&w=2250&q=80" /></div>
    </div>
    <div class="section" data-bgcolor="#D4CBE5">
      <h2 class="section--header">Zermatt, Switzerland</h2>
      <div class="section--image"><img src="https://images.unsplash.com/photo-1500817487388-039e623edc21?ixlib=rb-0.3.5&s=a21f754569632b81fd47dcaafe30b7c3&auto=format&fit=crop&w=2571&q=80" /></div>
    </div>
        <div class="section" data-bgcolor="#EDD4B2">
      <h2 class="section--header">Yellowstone, USA</h2>
      <div class="section--image"><img src="https://images.unsplash.com/photo-1482938289607-e9573fc25ebb?ixlib=rb-0.3.5&ixid=eyJhcHBfaWQiOjEyMDd9&s=0a5b239a157c3a39cf32283c50f9cd0c&auto=format&fit=crop&w=934&q=80" /></div>
    </div>
  </div>
</div>
!

CSS 

              
                @import url('https://fonts.googleapis.com/css?family=Nanum+Gothic+Coding');

:root {
  --color-text: #fff;
	--color-bg: #ddd;
  --font-text: 'Nanum Gothic Coding', monospace;
  --fontsize-text: 8vw;
}

body {
  min-height: 100vh;
	color: #000;
	color: var(--color-text);
	background-color: #fff;
	background: var(--color-bg);
	-webkit-font-smoothing: antialiased;
	-moz-osx-font-smoothing: grayscale;
  transition: background .3s;
}

.sections {
  position: relative;
  display: block;
  padding: 0 6vmax;
}

.section {
  position: relative;
  min-height: 100vh;
}

.section--image {
	display: block;
  position: relative;
  max-width: 100%;
  margin: 10vh 0 30vh auto;
  opacity: 0;
  transition: opacity .3s;
  
  .active & {
    opacity: 1;
  }
  
  img {
    display: block;
    position: relative;
    max-width: 90%;
    max-height: 100vh;
    margin: 0 0 0 auto;
  }
}

.section--header {
  font-size: calc(var(--fontsize-text));
	font-family: var(--font-text);
	position: fixed;
	bottom: 5vmax;
	left: 0;
	padding-left: 5vmax;
	z-index: 1000;
	line-height: 1;
  font-weight: 300;
  opacity: 0;
  animation-duration: .65s;
  animation-fill-mode: both;
  
  .active & {
    animation-name: fadeInUp;
  }
}

@keyframes fadeInUp{
  0% {
    transform: translate3d(0,55%,0);
    opacity:0;
    transform:translate3d(0,55%,0)
  } to {
    transform: translateZ(0);
    opacity:1;
    transform:translateZ(0)
  }
}
!

JS 

              
                // Get all of the images that are marked up to fade in
const images = document.querySelectorAll('.js-lazyload-image');

const sections = document.querySelectorAll('.section');

let config = {
  rootMargin: '0px',
  threshold: .5
};

let observer = new IntersectionObserver((entries) => {
    console.log(entries);
  entries.forEach(entry => {
    if (entry.isIntersecting) {
      intersectionHandler(entry);
    } 

  });
}, config);

sections.forEach(section => {
  observer.observe(section);
});

function intersectionHandler(entry) {
  const current = document.querySelector('.section.active');
  const next = entry.target;
  const header = next.querySelector(".section--header");

  if (current) {
    current.classList.remove('active');
  }
  if (next) {
    next.classList.add('active');
    document.body.style.setProperty("--color-bg", next.dataset.bgcolor);
  }
}

images.forEach(image => {
  observer.observe(image);
});

function preloadImage(img) {
  const src = img.getAttribute('data-src');
  if (!src) { return; }
  img.src = src;
}



// function onIntersection(entries) {
//   // Loop through the entries
//   for (var i = 0, len = entries.length; i < len; i++) {
//     // Are we in viewport?
//     if (entries[i].intersectionRatio > 0) {
//       console.log('in viewport');

//       // Stop watching and load the image
//       observer.unobserve(entries[i].target);
//       entries[i].target.classList.add('in-viewport');
//     }
//   }
// }
!
999px

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