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HTML

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HTML preprocessors can make writing HTML more powerful or convenient. For instance, Markdown is designed to be easier to write and read for text documents and you could write a loop in Pug.

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Adding Classes

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Insecure Resource

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CSS

About CSS Preprocessors

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

It's a common practice to apply CSS to a page that styles elements such that they are consistent across all browsers. We offer two of the most popular choices: normalize.css and a reset. Or, choose Neither and nothing will be applied.

Vendor Prefixing

About Vendor Prefixing

To get the best cross-browser support, it is a common practice to apply vendor prefixes to CSS properties and values that require them to work. For instance -webkit- or -moz-.

We offer two popular choices: Autoprefixer (which processes your CSS server-side) and -prefix-free (which applies prefixes via a script, client-side).

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JavaScript

About JavaScript Preprocessors

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

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Babel includes JSX processing.

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Packages

Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.

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HTML 

              
                - for(let c = 0; c < 13; c++)
  input.gallery__select(type="radio", name='gallery-select', id=c, checked=(c===0))
.gallery
  .gallery__filler
  .gallery__filler
  - for(let i = 0; i < 13; i++)
    label.gallery__item(for=i)
      img(src=`https://source.unsplash.com/random/400x400?bear,cat&v=${Math.floor(20 * Math.random() + i)}`, alt='Something random')
!

CSS 

              
                *
  box-sizing border-box
  animation  fadeIn .5s

body
  background       linear-gradient(65deg, black, black 20%, rebeccapurple)
  display          grid
  width            100vw
  padding-top      20px
  margin           0
  @media(min-width 768px)
    align-content center
    padding       20px

@keyframes fadeIn
  from
    opacity 0
  to
    opacity 1

img
  height 100%
  width 100%
  min-height 50px
  object-fit cover


.gallery
  display grid
  justify-content center
  grid-gap 20px
  grid-template-columns repeat(2, 100px) minmax(200px, 800px) repeat(2, 100px)
  grid-template-rows repeat(5, 100px)

  @media(max-width 768px)
    grid-gap 10px
    grid-template-columns repeat(auto-fit, 50px)
    grid-template-rows 300px repeat(auto-fit, 50px)

  &__filler
    grid-column span 2
    @media(max-width 768px)
      display none

  &__item
    cursor pointer
    border-radius 5px
    grid-row span 1
    grid-column span 1
    transition transform 0.1s ease-in-out

    &:hover
      transform scale(1.1) rotate(5deg)

  &__select
    display none

  for $select in (1..13)
    &__select:nth-of-type({$select})
      &:checked ~ .gallery .gallery__item:nth-of-type({$select})
        cursor default
        display grid
        align-items center
        grid-row 1 / -1
        grid-column 3

        &:hover
          transform none

        @media(max-width 768px)
          grid-row 1 / -3
          grid-column 1 / -1
!

JS 

              
                // ?
!
999px

Console