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In CodePen, whatever you write in the HTML editor is what goes within the <body> tags in a basic HTML5 template. If you need things in the <head> of the document, put that code here.

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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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About JavaScript Preprocessors

JavaScript preprocessors can help make authoring JavaScript easier and more convenient. For instance, CoffeeScript can help prevent easy-to-make mistakes and offer a cleaner syntax and Babel can bring ECMAScript 6 features to browsers that only support ECMAScript 5.

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You're using npm packages, so we've auto-selected Babel for you here, which we require to process imports and make it all work. If you need to use a different JavaScript preprocessor, remove the packages in the npm tab.

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Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

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About External Resources

You can apply a script from anywhere on the web to your Pen. Just put a URL to it here and we'll add it, in the order you have them, before the JavaScript in the Pen itself.

If the script you link to has the file extension of a preprocessor, we'll attempt to process it before applying.

You can also link to another Pen here, and we'll pull the JavaScript from that Pen and include it. If it's using a matching preprocessor, we'll combine the code before preprocessing, so you can use the linked Pen as a true dependency.

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HTML

            
              div#head.box
div.box
div.box
div.box
div.box
div.box
div.box
!

CSS

            
              colors = red orange yellow green cyan blue purple

reverse(i)
  100 - i

.box
  position absolute
  transform translate(10px, 10px)
  transition 0.1s transform ease-out
  width 40px
  height 40px
  background orange
  cursor pointer

  for color, i in colors
    &:nth-child({i + 1})
      background color
      z-index reverse(i)
      if color != red
        pointer-events: none
!

JS

            
              const headBox = document.getElementById('head')
const boxes = document.getElementsByClassName('box')
const mouseDown$ = Rx.Observable.fromEvent(headBox, 'mousedown')
const mouseMove$ = Rx.Observable.fromEvent(document, 'mousemove')
const mouseUp$ = Rx.Observable.fromEvent(document, 'mouseup')
const delayBoxes$ = Rx.Observable.from([].slice.call(boxes, 0))
  .zip(Rx.Observable.interval(100).startWith(0), (box) => box)

mouseDown$.map((e) => {
  const pos = getTranslate(headBox)
  return {
    pos,
    event: e,
  }
})
.switchMap((initialState) => {
  const initialPos = initialState.pos
  const { clientX, clientY } = initialState.event
  return mouseMove$.map((moveEvent) => ({
    x: moveEvent.clientX - clientX + initialPos.x,
    y: moveEvent.clientY - clientY + initialPos.y,
  }))
  .takeUntil(mouseUp$)
})
.mergeMap((pos) => {
  return delayBoxes$.do((box) => {
    setTranslate(box, pos)
  })
})
.subscribe()

function getTranslate (element) {
  const style = getComputedStyle(element)
  const regExp = /matrix\((\d+,\s){4}(\d+),\s(\d+)/i
  const result = style.transform.match(regExp)
  if (result) {
    return {
      x: parseInt(result[2], 10),
      y: parseInt(result[3], 10)
    }
  } else {
    return {
      x: 0,
      y: 0
    }
  }
}

function setTranslate (element, pos) {
  element.style.transform = `translate(${pos.x}px, ${pos.y}px)`
}
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999px
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