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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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About the <head>

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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).

Add External Stylesheets/Pens

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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 

              
                <div id="zap"></div>
!

CSS 

              
                // #divtober 31: Zap
// a.singlediv.com/divtober2020

white(alpha)
  rgba(255,255,255,alpha)

zap(angle)
  linear-gradient(angle, alpha(lime,0) 40%, alpha(lime,.5) 49.5%,
                         lime 49%, lime 51%,
                         alpha(lime,.5) 51.5%, alpha(lime,0) 60%)  

body
  min-height: 400px
  height: 100vh
  position: relative
  background-color: #444
  overflow: hidden

div
  position: absolute
  left: 50%
  top: 50%

  &:before,
  &:after
    display: block
    content: ''
    position: absolute

#zap
  font-size: 10px
  @media screen and (max-width: 400px)
    font-size: 8px
  width: 40em
  height: 35em
  margin-left: -(@width/2)
  top: auto
  bottom: 0
  background-repeat: no-repeat
  background-image: radial-gradient(circle, white 50%, white(0) 51%),  //left
                    radial-gradient(circle, #ccc 50%, transparent 51%),
                    radial-gradient(circle, #999 50%, transparent 51%),
                    repeating-linear-gradient(to bottom, #888, #888 .5em,
                                                         transparent .5em,
                                                         transparent 1.5em),
                    repeating-linear-gradient(to bottom, white, white .5em,
                                                         transparent .5em,
                                                         transparent 1.5em),
                    repeating-linear-gradient(to bottom, #ccc, #ccc .5em,
                                                         transparent .5em,
                                                         transparent 1.5em),
                    linear-gradient(to right, #aaa 50%, #ccc 50%),
                    radial-gradient(circle, white 50%, white(0) 51%), // right
                    radial-gradient(circle, #ccc 50%, transparent 51%),
                    radial-gradient(circle, #999 50%, transparent 51%),
                    repeating-linear-gradient(to bottom, #888, #888 .5em,
                                                         transparent .5em,
                                                         transparent 1.5em),
                    repeating-linear-gradient(to bottom, white, white .5em,
                                                         transparent .5em,
                                                         transparent 1.5em),
                    repeating-linear-gradient(to bottom, #ccc, #ccc .5em,
                                                         transparent .5em,
                                                         transparent 1.5em),
                    linear-gradient(to left, #aaa 50%, #ccc 50%),
                    zap(110deg),
                    zap(80deg),
                    zap(100deg),
                    zap(82deg),
                    zap(97deg),
                    zap(70deg),
                    zap(105deg),
                    zap(78deg),
                    zap(100deg),
                    zap(75deg),
                    zap(110deg),
                    zap(80deg),
                    zap(110deg),
                    zap(75deg),
                    zap(100deg),
                    zap(70deg),
                    zap(100deg),
                    zap(60deg),
                    linear-gradient(290deg, white(0) 50%, #ddd 51%),
                    linear-gradient(290deg, #ddd 50%, white(0) 51%)
  background-size: 3em 3em, // left
                   8em 8em,
                   9em 9em,
                   1.0em 65%,
                    .8em 65%,
                   2.5em 65%,
                   1.5em 80%,
                   3em 3em, // right
                   8em 8em,
                   9em 9em,
                   1.0em 65%,
                    .8em 65%,
                   2.5em 65%,
                   1.5em 80%,
                   4em 5em, // zap
                   4em 10em,
                   4em 9em,
                   4em 4em,
                   4em 3em,
                   4em 5em,
                   4em 4em,
                   4em 3em,
                   4em 5em,
                   4em 3em,
                   4em 5em,
                   4em 7em,
                   4em 5em,
                   4em 3em,
                   4em 2em,
                   4em 4em,
                   4em 6em,
                   4em 5em,
                   .8em 2em,
                   .8em 2em
  background-position: left 5.0em top 5.5em, // left
                       left 2.0em top 4.0em,
                       left 1.4em top 3.9em,
                       left 4.6em bottom,
                       left 6.3em bottom,
                       left 4.6em bottom,
                       left 5.1em bottom,
                       right 5.0em top 5.5em, // right
                       right 2.0em top 4.0em,
                       right 1.4em top 3.9em,
                       right 4.6em bottom,
                       right 6.3em bottom,
                       right 4.6em bottom,
                       right 5.1em bottom,
                        7.2em 5em, // zap
                        9.1em 5em,
                       10.8em 6em,
                       11.9em 6em,
                       12.4em 7em,
                       13.6em 7em,
                       15.1em 8em,
                       16.0em 8em,
                       16.8em 6em,
                       17.7em 6em,
                       19.1em 4em,
                       20.7em 4em,
                       22.2em 6em,
                       23.6em 6em,
                       24.2em 7em,
                       25.2em 7em,
                       26.5em 5em,
                       28.6em 5em,
                       5.8em 2em,
                       5.1em 0em

  &:before,
  &:after
    width: 36em
    height: @width
    left: 2em
    background-repeat: no-repeat
    background-image: linear-gradient(160deg, white(0) 50%, #ddd 51%),
                      linear-gradient(160deg, #ddd 50%, white(0) 51%),
                      linear-gradient(160deg, white(0) 50%, #ddd 51%),
                      linear-gradient(160deg, #ddd 50%, white(0) 51%)
    background-size: 2em .8em

  &:before
    top: -7em
    background-position: left 0   bottom 4em,
                         left 2em bottom 4.5em,
                         right 6em top 1.5em,
                         right 4em top 1em
    transform: rotate(55deg)

  &:after
    top: -8em
    background-position: left 2.5em top 4em,
                         left 4.5em top 4.5em,
                         right 2em bottom 7.5em,
                         right 0em bottom 7em
    transform: rotate(-55deg)
!

JS 

              
                // @lynnandtonic
// a.singlediv.com
!
999px

Console