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HTML

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CSS

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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 

              
                .exam
  .bear
  .xray__frame
  .xray
.instruction use mouse/finger to move x-ray
!

CSS 

              
                @import url('https://fonts.googleapis.com/css?family=Lato')

*
  box-sizing border-box

:root
  --pos 0

body
  background-color hsl(200, 50%, 80%)
  display flex
  align-items center
  justify-content center
  overflow auto
  padding 2rem
  position fixed
  min-height 100vh
  width 100vw
  font-family 'Lato', sans-serif

  @media(min-width 768px)
    position static


$height = 550px
$width = 300px
$mobile = 0.75
$boardHeight = $height * 0.20
$boardWidth = $width * 0.85

.bear
  height $height * $mobile
  width $width * $mobile
  background-position center

  @media(min-width 768px)
    height $height
    width $width

.bear
.xray
  background-size ($width * $mobile) ($height * $mobile)

  @media(min-width 768px)
    background-size $width $height

.exam
  cursor move
  cursor -webkit-grab
  position relative
  display flex
  justify-content center

.instruction
  position absolute
  top 50%
  left 50%
  transform translate(-50%, -50%) rotate(-90deg) translate(0, (($width * $mobile) * -0.6))
  font-weight bold
  font-size 1.5rem
  text-align center
  width 100vh
  color hsl(200, 50%, 30%)

  @media(min-width 768px)
    transform translate(-50%, -50%) rotate(-90deg) translate(0, (($width) * -0.6))

.xray
  background-color #111
  background-image url(https://jh3y-xray-bear.netlify.com/skeleton.svg)
  height ($boardHeight * $mobile)
  width ($boardWidth * $mobile)
  position absolute
  top calc(var(--pos) * 1px)
  left 50%
  background-position center calc(var(--pos) * -1px)
  transform translate(-50%, 0)

  @media(min-width 768px)
    height $boardHeight
    width $boardWidth

  &__frame
    border-radius 6px
    height (($boardHeight * $mobile) + 10px)
    width (($boardWidth * $mobile) + 10px)
    position absolute
    top calc((var(--pos) * 1px) - 5px)
    left 50%
    transform translate(-50%, 0)
    border 5px solid silver

    @media(min-width 768px)
      height ($boardHeight + 10px)
      width ($boardWidth + 10px)

    &:after
    &:before
      border-radius 10px 0 0 10px
      content ''
      position absolute
      transform translate(-100%, 0)
      height 20%
      width 10px
      left -5px

    &:before
      background #2eec7a
      top 20%

    &:after
      background #ffcb05
      top 50%


.bear
  background-image url(https://jh3y-xray-bear.netlify.com/bear.svg)
!

JS 

              
                const exam = document.querySelector('.exam')
const xray = document.querySelector('.xray')
const updateXray = (e) => {
  const y = e.touches ? e.touches[0].clientY : e.y
  const examArea = exam.getBoundingClientRect()
  const xrayArea = xray.getBoundingClientRect()
  const perc = (y - examArea.top) / examArea.height
  const pos = Math.floor(Math.max(0, Math.min(perc * examArea.height, examArea.height - xrayArea.height)))
  document.documentElement.style.setProperty('--pos', pos)
}

exam.addEventListener('mousemove', updateXray)
exam.addEventListener('touchmove', updateXray)
!
999px

Console