style.css

/* Import Google font - Poppins */
@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@400;500;600&display=swap');
* {
  font-family: 'Poppins', sans-serif;
}
body {
  padding: 0 30px;
}
#src-btn, .screenshot {
  position: fixed;
  left: 50%;
  transform: translate(-50%, -50%);
}
#src-btn {
  bottom: 15px;
  border: none;
  outline: none;
  color: #fff;
  cursor: pointer;
  font-size: 1rem;
  padding: 15px 25px;
  border-radius: 30px;
  background: #4a98f7;
}
.src-preview {
  position: fixed;
  left: 0;
  top: 0;
  height: 100%;
  width: 100%;
  opacity: 0;
  pointer-events: none;
  background: rgba(0,0,0,0.65);
  transition: all 0.15s ease;
}
.src-preview.show {
  opacity: 1;
  pointer-events: auto;
}
.src-preview .screenshot {
  width: 70%;
  top: 50%;
  opacity: 0;
  pointer-events: none;
  aspect-ratio: 16 / 9;
  transition: transform 0.15s ease;
  transform: translate(-50%, -50%) scale(0.9);
}
.src-preview.show .screenshot{
  opacity: 1;
  pointer-events: auto;
  transform: translate(-50%, -50%) scale(1);
}
.screenshot #close-btn {
  position: absolute;
  right: -25px;
  color: #fff;
  cursor: pointer;
  font-size: 1.1rem;
}
.screenshot img {
  width: 100%;
}