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HTML

About HTML Preprocessors

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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!
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-.

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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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HTML 

              
                h1 box-shadow pseudo loaders
.loading.loading--one
.loading.loading--two
.loading.loading--three
.loading.loading--four
!

CSS 

              
                h1
  color #fafafa
  text-align center

$loader-color  = #e74c3c
$loader-size   = 20px
$loader-margin = 5px
$first = $loader-size + $loader-margin
$second = (2 * $loader-size) + (2 * $loader-margin)
$third = (3 * $loader-size) + (3 * $loader-margin)
$fourth = (4 * $loader-size) + (4 * $loader-margin)
$fifth = (5 * $loader-size) + (5 * $loader-margin)
$hide = -1 * $loader-size
$bounce = -1 * $first

*
  box-sizing border-box

body
  background-color #111
  text-align center
  
.loading
  width 200px
  height 200px
  display inline-block
  position relative
  border-radius 10px
  background-color #eee
  border 4px solid grey
  margin 20px 10px
  &--one
    &:after
      content          ''
      position         absolute
      top              50%
      left             50%
      // full width is 20 + (5*20) + margin       
      margin-left      -(($fifth / 2) + $loader-size)
      margin-top       -($loader-size / 2)
      background-color transparent
      height           $loader-size
      width            $loader-size
      border-radius    100%

      box-shadow $first 0 0 0 $loader-color,
        $second $first 0 0 $loader-color,
        $second (-1 * $first) 0 0 $loader-color,
        $second 0 0 0 $loader-color,
        $third (-1 * $second) 0 0 $loader-color,
        $third (-1 * $first) 0 0 $loader-color,
        $third 0 0 0 $loader-color,
        $third $first 0 0 $loader-color,
        $third $second 0 0 $loader-color,
        $fourth $first 0 0 $loader-color,
        $fourth 0 0 0 $loader-color,
        $fourth (-1 * $first) 0 0 $loader-color,    
        $fifth 0 0 0 $loader-color

      animation square 1s infinite linear


  &--two
    &:after
      content          ''
      position         absolute
      top              50%
      left             50%
      margin-left      -(($fifth / 2) + $loader-size)
      margin-top       -($loader-size / 2)
      background-color transparent
      height           $loader-size
      width            $loader-size
      border-radius    100%
      animation bobble 1s infinite ease
      box-shadow $first 0 0 0 $loader-color,
        $second 0 0 0 $loader-color,
        $third 0 0 0 $loader-color,
        $fourth 0 0 0 $loader-color,
        $fifth 0 0 0 $loader-color
      
  &--three
    &:after
      content          ''
      position         absolute
      top              50%
      left             50%
      margin-left      -(($third / 2) + $loader-size)
      margin-top       -($loader-size / 2)
      background-color transparent
      height           $loader-size
      width            $loader-size
      border-radius    100%
      animation snake 2s infinite ease
      box-shadow $first $first 0 0 $loader-color,
        $second $first 0 0 $loader-color,
        $third $first 0 0 $loader-color,
        $third 0 0 0 $loader-color,
        $third (-1 * $first) 0 0 $loader-color,
        $second (-1 * $first) 0 0 $loader-color,
        $first (-1 * $first) 0 0 $loader-color,
        $first 0 0 0 $loader-color,
        $second 0 0 0 $loader-color
  &--four
    &:after
      content          ''
      position         absolute
      top              50%
      left             50%
      margin-left      -(($fifth / 2) + $loader-size)
      margin-top       -($loader-size / 2)
      background-color transparent
      height           $loader-size
      width            $loader-size
      border-radius    100%
      animation bridge .75s infinite ease
      box-shadow $first 0 0 0 $loader-color,
        $second 0 0 0 $loader-color,
        $third 0 0 0 $loader-color,
        $fourth 0 0 0 $loader-color,
        $fifth 0 0 0 $loader-color

        
        
@keyframes bridge
  0%
    box-shadow $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $fourth 0 0 0 $loader-color,
      $fifth 0 0 0 $loader-color
  15%
    box-shadow $first $bounce 0 0 $loader-color,
      $second 0 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $fourth 0 0 0 $loader-color,
      $fifth 0 0 0 $loader-color
  30%
    box-shadow $first 0 0 0 $loader-color,
      $second $bounce 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $fourth 0 0 0 $loader-color,
      $fifth 0 0 0 $loader-color
  45%
    box-shadow $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color,
      $third $bounce 0 0 $loader-color,
      $fourth 0 0 0 $loader-color,
      $fifth 0 0 0 $loader-color
  60%
    box-shadow $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $fourth $bounce 0 0 $loader-color,
      $fifth 0 0 0 $loader-color    
  75%
    box-shadow $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $fourth 0 0 0 $loader-color,
      $fifth $bounce 0 0 $loader-color  
  100%
    box-shadow $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $fourth 0 0 0 $loader-color,
      $fifth 0 0 0 $loader-color    
  
@keyframes bobble
  0%
    box-shadow $first 0 0 $hide $loader-color,
      $second 0 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $fourth 0 0 $hide $loader-color,
      $fifth 0 0 $hide $loader-color
  10%
    box-shadow $first 0 0 0 $loader-color,
      $second 0 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $fourth 0 0 $hide $loader-color,
      $fifth 0 0 $hide $loader-color
  20%
    box-shadow $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color,
      $third 0 0 $hide $loader-color,
      $fourth 0 0 $hide $loader-color,
      $fifth 0 0 $hide $loader-color
  30%
    box-shadow $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $fourth 0 0 $hide $loader-color,
      $fifth 0 0 $hide $loader-color
  40%
    box-shadow $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $fourth 0 0 0 $loader-color,
      $fifth 0 0 $hide $loader-color
  50%
    box-shadow $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $fourth 0 0 0 $loader-color,
      $fifth 0 0 0 $loader-color
  60%
    box-shadow $first 0 0 $hide $loader-color,
      $second 0 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $fourth 0 0 0 $loader-color,
      $fifth 0 0 0 $loader-color
  70%
    box-shadow $first 0 0 $hide $loader-color,
      $second 0 0 $hide $loader-color,
      $third 0 0 0 $loader-color,
      $fourth 0 0 0 $loader-color,
      $fifth 0 0 0 $loader-color
  80%
    box-shadow $first 0 0 $hide $loader-color,
      $second 0 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $fourth 0 0 0 $loader-color,
      $fifth 0 0 0 $loader-color
  90%
    box-shadow $first 0 0 $hide $loader-color,
      $second 0 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $fourth 0 0 $hide $loader-color,
      $fifth 0 0 0 $loader-color
  100%
    box-shadow $first 0 0 $hide $loader-color,
      $second 0 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $fourth 0 0 $hide $loader-color,
      $fifth 0 0 $hide $loader-color
    
    
@keyframes square
  0%
    box-shadow $first 0 0 $hide $loader-color,
      $second $first 0 $hide $loader-color,
      $second (-1 * $first) 0 $hide $loader-color,
      $second 0 0 $hide $loader-color,
      $third (-1 * $second) 0 $hide $loader-color,
      $third (-1 * $first) 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $third $first 0 $hide $loader-color,
      $third $second 0 $hide $loader-color,
      $fourth $first 0 $hide $loader-color,
      $fourth 0 0 $hide $loader-color,
      $fourth (-1 * $first) 0 $hide $loader-color,    
      $fifth 0 0 $hide $loader-color
  10%
    box-shadow $first 0 0 0 $loader-color,
      $second $first 0 $hide $loader-color,
      $second (-1 * $first) 0 $hide $loader-color,
      $second 0 0 $hide $loader-color,
      $third (-1 * $second) 0 $hide $loader-color,
      $third (-1 * $first) 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $third $first 0 $hide $loader-color,
      $third $second 0 $hide $loader-color,
      $fourth $first 0 $hide $loader-color,
      $fourth 0 0 $hide $loader-color,
      $fourth (-1 * $first) 0 $hide $loader-color,    
      $fifth 0 0 $hide $loader-color
  20%
    box-shadow $first 0 0 0 $loader-color,
      $second $first 0 0 $loader-color,
      $second (-1 * $first) 0 0 $loader-color,
      $second 0 0 0 $loader-color,
      $third (-1 * $second) 0 $hide $loader-color,
      $third (-1 * $first) 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $third $first 0 $hide $loader-color,
      $third $second 0 $hide $loader-color,
      $fourth $first 0 $hide $loader-color,
      $fourth 0 0 $hide $loader-color,
      $fourth (-1 * $first) 0 $hide $loader-color,    
      $fifth 0 0 $hide $loader-color 
  30%
    box-shadow $first 0 0 0 $loader-color,
      $second $first 0 0 $loader-color,
      $second (-1 * $first) 0 0 $loader-color,
      $second 0 0 0 $loader-color,
      $third (-1 * $second) 0 0 $loader-color,
      $third (-1 * $first) 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $third $first 0 0 $loader-color,
      $third $second 0 0 $loader-color,
      $fourth $first 0 $hide $loader-color,
      $fourth 0 0 $hide $loader-color,
      $fourth (-1 * $first) 0 $hide $loader-color,    
      $fifth 0 0 $hide $loader-color
  40%
    box-shadow $first 0 0 0 $loader-color,
      $second $first 0 0 $loader-color,
      $second (-1 * $first) 0 0 $loader-color,
      $second 0 0 0 $loader-color,
      $third (-1 * $second) 0 0 $loader-color,
      $third (-1 * $first) 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $third $first 0 0 $loader-color,
      $third $second 0 0 $loader-color,
      $fourth $first 0 0 $loader-color,
      $fourth 0 0 0 $loader-color,
      $fourth (-1 * $first) 0 0 $loader-color,    
      $fifth 0 0 $hide $loader-color
  50%
    box-shadow $first 0 0 0 $loader-color,
      $second $first 0 0 $loader-color,
      $second (-1 * $first) 0 0 $loader-color,
      $second 0 0 0 $loader-color,
      $third (-1 * $second) 0 0 $loader-color,
      $third (-1 * $first) 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $third $first 0 0 $loader-color,
      $third $second 0 0 $loader-color,
      $fourth $first 0 0 $loader-color,
      $fourth 0 0 0 $loader-color,
      $fourth (-1 * $first) 0 0 $loader-color,    
      $fifth 0 0 0 $loader-color
  60%
    box-shadow $first 0 0 $hide $loader-color,
      $second $first 0 0 $loader-color,
      $second (-1 * $first) 0 0 $loader-color,
      $second 0 0 0 $loader-color,
      $third (-1 * $second) 0 0 $loader-color,
      $third (-1 * $first) 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $third $first 0 0 $loader-color,
      $third $second 0 0 $loader-color,
      $fourth $first 0 0 $loader-color,
      $fourth 0 0 0 $loader-color,
      $fourth (-1 * $first) 0 0 $loader-color,    
      $fifth 0 0 0 $loader-color
  70%
    box-shadow $first 0 0 $hide $loader-color,
      $second $first 0 $hide $loader-color,
      $second (-1 * $first) 0 $hide $loader-color,
      $second 0 0 $hide $loader-color,
      $third (-1 * $second) 0 0 $loader-color,
      $third (-1 * $first) 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $third $first 0 0 $loader-color,
      $third $second 0 0 $loader-color,
      $fourth $first 0 0 $loader-color,
      $fourth 0 0 0 $loader-color,
      $fourth (-1 * $first) 0 0 $loader-color,    
      $fifth 0 0 0 $loader-color
  80%
    box-shadow $first 0 0 $hide $loader-color,
      $second $first 0 $hide $loader-color,
      $second (-1 * $first) 0 $hide $loader-color,
      $second 0 0 $hide $loader-color,
      $third (-1 * $second) 0 $hide $loader-color,
      $third (-1 * $first) 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $third $first 0 $hide $loader-color,
      $third $second 0 $hide $loader-color,
      $fourth $first 0 0 $loader-color,
      $fourth 0 0 0 $loader-color,
      $fourth (-1 * $first) 0 0 $loader-color,    
      $fifth 0 0 0 $loader-color
  90%
    box-shadow $first 0 0 $hide $loader-color,
      $second $first 0 $hide $loader-color,
      $second (-1 * $first) 0 $hide $loader-color,
      $second 0 0 $hide $loader-color,
      $third (-1 * $second) 0 $hide $loader-color,
      $third (-1 * $first) 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $third $first 0 $hide $loader-color,
      $third $second 0 $hide $loader-color,
      $fourth $first 0 $hide $loader-color,
      $fourth 0 0 $hide $loader-color,
      $fourth (-1 * $first) 0 $hide $loader-color,    
      $fifth 0 0 0 $loader-color
  100%
    box-shadow $first 0 0 $hide $loader-color,
      $second $first 0 $hide $loader-color,
      $second (-1 * $first) 0 $hide $loader-color,
      $second 0 0 $hide $loader-color,
      $third (-1 * $second) 0 $hide $loader-color,
      $third (-1 * $first) 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $third $first 0 $hide $loader-color,
      $third $second 0 $hide $loader-color,
      $fourth $first 0 $hide $loader-color,
      $fourth 0 0 $hide $loader-color,
      $fourth (-1 * $first) 0 $hide $loader-color,    
      $fifth 0 0 $hide $loader-color
    
@keyframes snake
  0%
  5%
    box-shadow $first $first 0 $hide $loader-color,
      $second $first 0 $hide $loader-color,
      $third $first 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $third (-1 * $first) 0 $hide $loader-color,
      $second (-1 * $first) 0 $hide $loader-color,
      $first (-1 * $first) 0 $hide $loader-color,
      $first 0 0 $hide $loader-color,
      $second 0 0 $hide $loader-color
  10%
    box-shadow $first $first 0 0 $loader-color,
      $second $first 0 $hide $loader-color,
      $third $first 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $third (-1 * $first) 0 $hide $loader-color,
      $second (-1 * $first) 0 $hide $loader-color,
      $first (-1 * $first) 0 $hide $loader-color,
      $first 0 0 $hide $loader-color,
      $second 0 0 $hide $loader-color
  15%
    box-shadow $first $first 0 0 $loader-color,
      $second $first 0 0 $loader-color,
      $third $first 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $third (-1 * $first) 0 $hide $loader-color,
      $second (-1 * $first) 0 $hide $loader-color,
      $first (-1 * $first) 0 $hide $loader-color,
      $first 0 0 $hide $loader-color,
      $second 0 0 $hide $loader-color
  20%
    box-shadow $first $first 0 0 $loader-color,
      $second $first 0 0 $loader-color,
      $third $first 0 0 $loader-color,
      $third 0 0 $hide $loader-color,
      $third (-1 * $first) 0 $hide $loader-color,
      $second (-1 * $first) 0 $hide $loader-color,
      $first (-1 * $first) 0 $hide $loader-color,
      $first 0 0 $hide $loader-color,
      $second 0 0 $hide $loader-color
  25%
    box-shadow $first $first 0 0 $loader-color,
      $second $first 0 0 $loader-color,
      $third $first 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $third (-1 * $first) 0 $hide $loader-color,
      $second (-1 * $first) 0 $hide $loader-color,
      $first (-1 * $first) 0 $hide $loader-color,
      $first 0 0 $hide $loader-color,
      $second 0 0 $hide $loader-color
  30%
    box-shadow $first $first 0 0 $loader-color,
      $second $first 0 0 $loader-color,
      $third $first 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $third (-1 * $first) 0 0 $loader-color,
      $second (-1 * $first) 0 $hide $loader-color,
      $first (-1 * $first) 0 $hide $loader-color,
      $first 0 0 $hide $loader-color,
      $second 0 0 $hide $loader-color
  35%
    box-shadow $first $first 0 0 $loader-color,
      $second $first 0 0 $loader-color,
      $third $first 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $third (-1 * $first) 0 0 $loader-color,
      $second (-1 * $first) 0 0 $loader-color,
      $first (-1 * $first) 0 $hide $loader-color,
      $first 0 $hide $loader-color,
      $second 0 $hide $loader-color    
  40%
    box-shadow $first $first 0 0 $loader-color,
      $second $first 0 0 $loader-color,
      $third $first 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $third (-1 * $first) 0 0 $loader-color,
      $second (-1 * $first) 0 0 $loader-color,
      $first (-1 * $first) 0 0 $loader-color,
      $first 0 0 $hide $loader-color,
      $second 0 0 $hide $loader-color
  45%
    box-shadow $first $first 0 0 $loader-color,
      $second $first 0 0 $loader-color,
      $third $first 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $third (-1 * $first) 0 0 $loader-color,
      $second (-1 * $first) 0 0 $loader-color,
      $first (-1 * $first) 0 0 $loader-color,
      $first 0 0 0 $loader-color,
      $second 0 0 $hide $loader-color
  50%
    box-shadow $first $first 0 0 $loader-color,
      $second $first 0 0 $loader-color,
      $third $first 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $third (-1 * $first) 0 0 $loader-color,
      $second (-1 * $first) 0 0 $loader-color,
      $first (-1 * $first) 0 0 $loader-color,
      $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color
  55%
    box-shadow $first $first 0 $hide $loader-color,
      $second $first 0 0 $loader-color,
      $third $first 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $third (-1 * $first) 0 0 $loader-color,
      $second (-1 * $first) 0 0 $loader-color,
      $first (-1 * $first) 0 0 $loader-color,
      $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color
  60%
    box-shadow $first $first 0 $hide $loader-color,
      $second $first 0 $hide $loader-color,
      $third $first 0 0 $loader-color,
      $third 0 0 0 $loader-color,
      $third (-1 * $first) 0 0 $loader-color,
      $second (-1 * $first) 0 0 $loader-color,
      $first (-1 * $first) 0 0 $loader-color,
      $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color
  65%
    box-shadow $first $first 0 $hide $loader-color,
      $second $first 0 $hide $loader-color,
      $third $first 0 $hide $loader-color,
      $third 0 0 0 $loader-color,
      $third (-1 * $first) 0 0 $loader-color,
      $second (-1 * $first) 0 0 $loader-color,
      $first (-1 * $first) 0 0 $loader-color,
      $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color
  70%
    box-shadow $first $first 0 $hide $loader-color,
      $second $first 0 $hide $loader-color,
      $third $first 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $third (-1 * $first) 0 0 $loader-color,
      $second (-1 * $first) 0 0 $loader-color,
      $first (-1 * $first) 0 0 $loader-color,
      $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color    
  75%
    box-shadow $first $first 0 $hide $loader-color,
      $second $first 0 $hide $loader-color,
      $third $first 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $third (-1 * $first) 0 $hide $loader-color,
      $second (-1 * $first) 0 0 $loader-color,
      $first (-1 * $first) 0 0 $loader-color,
      $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color
  80%
    box-shadow $first $first 0 $hide $loader-color,
      $second $first 0 $hide $loader-color,
      $third $first 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $third (-1 * $first) 0 $hide $loader-color,
      $second (-1 * $first) 0 $hide $loader-color,
      $first (-1 * $first) 0 0 $loader-color,
      $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color
  85%
    box-shadow $first $first 0 $hide $loader-color,
      $second $first 0 $hide $loader-color,
      $third $first 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $third (-1 * $first) 0 $hide $loader-color,
      $second (-1 * $first) 0 $hide $loader-color,
      $first (-1 * $first) 0 $hide $loader-color,
      $first 0 0 0 $loader-color,
      $second 0 0 0 $loader-color
  90%
    box-shadow $first $first 0 $hide $loader-color,
      $second $first 0 $hide $loader-color,
      $third $first 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $third (-1 * $first) 0 $hide $loader-color,
      $second (-1 * $first) 0 $hide $loader-color,
      $first (-1 * $first) 0 $hide $loader-color,
      $first 0 0 $hide $loader-color,
      $second 0 0 0 $loader-color
  95%
  100%
    box-shadow $first $first 0 $hide $loader-color,
      $second $first 0 $hide $loader-color,
      $third $first 0 $hide $loader-color,
      $third 0 0 $hide $loader-color,
      $third (-1 * $first) 0 $hide $loader-color,
      $second (-1 * $first) 0 $hide $loader-color,
      $first (-1 * $first) 0 $hide $loader-color,
      $first 0 0 $hide $loader-color,
      $second 0 0 $hide $loader-color
!

JS
!
999px

Console