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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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Babel includes JSX processing.

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HTML 

              
                - const SIZE = 150
-
  const IMAGES = [
    `https://i.picsum.photos/id/21/200/200.jpg?hmac=a2iQ6UhOjpU6jn7QSsCpk1CiiKTxmW1R4UivDsv-n8o`,
    `https://i.picsum.photos/id/139/200/200.jpg?hmac=FNSPvHsHcRzKQtNxKKauJgIXpoaAufCwYvr-1w5T3R4`,
    `https://i.picsum.photos/id/642/200/200.jpg?hmac=MJkhEaTWaybCn0y7rKfh_irNHvVuqRHmxcpziWABTKw`,
    `https://i.picsum.photos/id/253/200/200.jpg?hmac=_dceojr9yz5ZIKoye8I9HOqPCBHfn-jT9aRYdoLx1kQ`,
    `https://i.picsum.photos/id/604/200/200.jpg?hmac=qgFjxODI1hMBMfHo68VvLeji-zvG9y-iPYhyW0EkvOs`,
    `https://i.picsum.photos/id/119/200/200.jpg?hmac=JGrHG7yCKfebsm5jJSWw7F7x2oxeYnm5YE_74PhnRME`,
    `https://i.picsum.photos/id/520/200/200.jpg?hmac=gq6GVKg64GMqsvk_d6gzXZ7L1htska1jEdgBnAwm4xU`,
    `https://i.picsum.photos/id/553/200/200.jpg?hmac=HSLKzqqoxnajv4KjLxYSjZokWcuCCiZLGdRPUoryhXk`,
    `https://i.picsum.photos/id/988/200/200.jpg?hmac=-lwK-i6PssD9WlUeVPDIhOxDVxlzJKeM4MgEx_fIqJg`

  ]
-
  const CLIPS = [
    ['ellipse(0 0 at 0 0)', 'ellipse(150% 150% at 0 0)'],
    ['inset(100% 0 0 0)', 'inset(0 0 0 0)'],
    ['ellipse(0 0 at 100% 0)', 'ellipse(150% 150% at 100% 0)'],
    ['polygon(50% 50%,  50% 50%,  50% 50%, 50% 50%)', 'polygon(-50% 50%, 50% -50%, 150% 50%, 50% 150%)'],
    ['circle(0)', 'circle(125%)'],
    ['inset(100% 100% 100% 100%)', 'inset(0 0 0 0)'],
    ['ellipse(0 0 at 0 100%)', 'ellipse(150% 150% at 0 100%)'],
    ['inset(0 0 100% 0)', 'inset(0 0 0 0)'],
    ['ellipse(0 0 at 100% 100%)', 'ellipse(150% 150% at 100% 100%)'],
    //- Other shapes to play with!
    //- ['inset(0 100% 0 0)', 'inset(0 0 0 0)'],
    //- ['inset(100% 100% 0 0)', 'inset(0 0 0 0)'],
    //- ['inset(0 0 0 100%)', 'inset(0 0 0 0)'],
    //- ['inset(0 100% 100% 0)', 'inset(0 0 0 0)'],
    //- ['inset(0 0 100% 100%)', 'inset(0 0 0 0)'],
    //- ['inset(100% 0 0 100%)', 'inset(0 0 0 0)'],
    //- ['inset(100% 0 100% 0)', 'inset(0 0 0 0)'],
    //- ['inset(0 100% 0 100%)', 'inset(0 0 0 0)'],
    //- ['polygon(50% 50%, 50% 50%, 50% 50%, 50% 50%, 50% 50%, 50% 50%, 50% 50%, 50% 50%, 50% 50%, 50% 50%)', 'polygon(-70% 198%, 50% 114%, 170% 198%, 118% 54%, 234% -45%, 90% -10%, 50% -130%, 10% -10%, -134% -45%, -18% 54%)'],
    //- ['inset(0 100% 0 0)', 'inset(0 0 0 0)'],
    //- ['inset(0 100% 0 0)', 'inset(0 0 0 0)'],
    //- ['inset(0 100% 0 0)', 'inset(0 0 0 0)'],
    //- ['inset(0 100% 0 0)', 'inset(0 0 0 0)'],
    //- ['inset(0 100% 0 0)', 'inset(0 0 0 0)'],
    //- ['inset(0 100% 0 0)', 'inset(0 0 0 0)'],
    //- ['inset(0 100% 0 0)', 'inset(0 0 0 0)'],
  ]
mixin image(src, start, end)
  .image(style=`--clip-start: ${start}; --clip-end: ${end};`)
    img(src=src)
    img(src=src)

.image-container
  - let i = 0
  while i < 9
    +image(IMAGES[i], CLIPS[i][0], CLIPS[i][1])
    - i++
!

CSS 

              
                *
  box-sizing border-box

body
  min-height 100vh
  display flex
  align-items center
  justify-content center

.image-container
  display grid
  grid-template-columns repeat(3, 1fr)
  grid-template-rows repeat(3, 1fr)
  width 600px
  grid-gap 0.5rem

  .image
    position relative
    padding-bottom 100%

    img
      height 100%
      width 100%
      object-fit cover
      left 0
      position absolute
      top 0

    img:nth-of-type(1)
      filter grayscale(1) brightness(40%)

    img:nth-of-type(2)
      clip-path var(--clip-start)
      transition clip-path 0.5s

    &:hover img:nth-of-type(2)
      clip-path var(--clip-end)
!

JS 

              
                // Nope
// Using Pug && Stylus for convenience. View compiled to see HTML + CSS
!
999px

Console