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HTML 

              
                <header>
  <h1><span class="spot">Spotify</span> Duotone Effect</h1>
  <h2>Using CSS filters, blend modes, and pseudo-elements</h2>
  <p>(Hover over the image to see the original.)</p>
  <button class="btn" id="btn">Alternate Version</button>
</header>

<div class="grid-container">
  <figure class="spot-grad">
    <img src="https://drive.google.com/uc?export=view&id=0B8HLX1nN4xatZmRNbzYyWlJvdVk" alt="shirley manson" />
    <div class="adjust"></div>
  </figure>
  <figure class="spot-grad">
    <img src="https://drive.google.com/uc?export=view&id=0B8HLX1nN4xatLTAzcF9rOTZYVUE" alt="neko case" />
    <div class="adjust"></div>
  </figure>
  <figure class="spot-grad">
    <img src="https://drive.google.com/uc?export=view&id=0B8HLX1nN4xatU2dqUXlJaVFRNWM" alt="joanna newsom" />
    <div class="adjust"></div>
  </figure>
  <figure class="spot-grad">
    <img src="https://drive.google.com/uc?export=view&id=0B8HLX1nN4xatNDBTTTlQSTlkZjA" alt="beyonce" />
    <div class="adjust"> </div>
  </figure>
  <figure class="spot-grad">
    <img src="https://drive.google.com/uc?export=view&id=0B8HLX1nN4xatcC1KTkNTTVhsYzA" alt="tori amos" />
    <div class="adjust"></div>
  </figure>
</div>
!

CSS 

              
                .spot-grad::before,
.spot-grad::after,
.adjust {
  position: absolute;
  content: '';
  top: 0;
  left: 0;
  bottom: 0;
  right: 0;
  pointer-events: none;
}

@supports (filter: grayscale(1)) {
  .spot-grad img {
    filter: grayscale(1) contrast(.7) brightness(1.3);
  }
}

/* main color */
@supports (mix-blend-mode: exclusion) {
  .spot-grad::before {
    z-index: 1;
    background: rgb(126, 8, 150);
    mix-blend-mode: exclusion;
  }
/* alternate 'red' version   */
  body.red .spot-grad::before {
    background: rgb(0, 81, 102);
  }
}

/* bring in the secondary tones */
@supports (mix-blend-mode: difference) {
  .spot-grad::after {
    z-index: 2;
    background: rgb(13, 53, 255);
    mix-blend-mode: difference;
  }
/* alternate 'red' version  */
  body.red .spot-grad::after {
  background: rgb(53, 107, 215);
  }
}

/* tones down the Frankenstein effect */
@supports (mix-blend-mode: overlay) {
  .adjust {
    z-index: 3;
    background: hsl(248, 17%, 66%);
    mix-blend-mode: overlay;
  }
/* alternate 'red' version   */
  body.red .adjust {
    background: hsl(322, 28%, 53%);
  }
}

/* general styles */

* {
  box-sizing: border-box;
}

html, body {
  height: 100%;
}

body {
  margin: 0;
  background: #222023;
}

.grid-container {
  max-width: 50rem;
  min-height: 100vh;
  display: flex;
  flex-wrap: wrap;
  margin: 2rem auto 0;
}

header {
  padding: 1rem 1rem 0;
  text-align: center;
  color:#fffffc;
  font-size: 2vmax;    
  font-family: 'Open Sans', sans-serif;
}

h1 {
  font-weight: 700;
  font-family: 'Montserrat', sans-serif;
} 

h2 {
  font-style: italic;
  font-weight: 300;
  font-size: 1.5em;
}

header p {
  font-style: italic;
  font-weight: 400;
  font-family: 'Open Sans', sans-serif;
  font-size: 0.88em;
  color: #9897a9;
}

.btn {
  display: inline-block;
  padding: 0.75em 1em;
  background: transparent;
  border: 0.225em solid;
  border-image: linear-gradient(60deg, #19016f, #d33249);
  border-image-slice: 1;
  font-weight: 400;
  font-family: 'Open Sans', sans-serif;
  color: #fffffc;
  text-transform: uppercase;
  font-size: 0.9em;
  letter-spacing: 1px;
  cursor: pointer;
}

body.red .btn {
  border-image: linear-gradient(60deg, #bf30de, #9cf0e1);    
  border-image-slice: 1;
}

.btn:hover {
  background: linear-gradient(60deg, #19016f, #d33249);    
}

body.red .btn:hover {
  background: linear-gradient(60deg, #bf30de, #9cf0e1);    
}

.spot {
  margin-right: 3.75ch;
}

.spot::after {
  position: absolute;
  margin-left: 0.1em;
  content: '(ish)';
  color: #bf30de;
  transform: rotate(-10deg);
  transform-origin: top left;
}

body.red .spot::after {
  color: #d33249;
}


.spot-grad {
  position: relative;
  min-height: 10rem;
  max-height: 15rem;
  margin: 0;
  display: flex;
  flex-basis: 100%;
  flex-grow: 1;
}

.spot-grad img {
  object-fit: cover;
  max-width: 100%;
}

/* reverts the image to original on hover */

.spot-grad:hover::before,
.spot-grad:hover::after,
.spot-grad:hover .adjust {
  opacity: 0;
}

.spot-grad:hover img {
  filter: none;
}

@media screen and (min-width: 40rem) {
  .grid-container {
    padding: 0 1rem;
    margin-bottom: 2rem;
  }
  .spot-grad:not(:nth-of-type(1)) {
    flex-basis: calc(50% - 0.25em);
    margin-top: 0.5rem;
  }
  .spot-grad:nth-child(2n+3) {
    margin-left: 0.5em;
  }
}

@media screen and (min-width: 62rem) {
  header {
    font-size: 1.4rem;
  }
}
!

JS 

              
                var btn = document.getElementById('btn');

btn.addEventListener('click', function() {
    document.body.classList.toggle('red');
}, false);
!
999px

Console