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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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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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Using packages here is powered by esm.sh, which makes packages from npm not only available on a CDN, but prepares them for native JavaScript ESM usage.

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HTML 

              
                #app
  form
    .input-wrapper
      .input
        input(type="email" id="email" pattern=".{1,}" required placeholder=" ")
        label Email Address
      .alert
        p invalid email address
    button#submit-button(type="submit") SUBMIT
!

CSS 

              
                body
  display: grid
  place-items: center center
  height: 100vh
  background-color: #F2C22B

.input-wrapper
  position: relative
  margin-bottom: 12px
  transition: margin 300ms ease-in-out
  
  .input
    position: relative
    background-color: white
    z-index: 1
    border-radius: 6px
    border: 1px solid #D5DBDB
  
  .alert
    position: absolute
    z-index: 0
    top: calc(100% - 5px)
    left: 0
    padding: 7px 6px 4px 6px
    font-size: 10px
    border: 1px solid red
    border-top: 0
    width: 100%
    border-radius: 0 0 6px 6px
    background-color: #FADBD8
    color: red
    transform: translateY(-100%)
    opacity: 0
    transition: all 300ms ease-out

    p
      margin: 0
  
  input, label
    font-size: 20px
    border: 0 solid

  input
    position: relative
    padding: 18px 10px
    border-color: #D5DBDB
    background-color: transparent
    z-index: 1

    &:focus + label
      transform: scale(0.5)
      top: 6px

    &:not(:placeholder-shown) + label
      transform: scale(0.5)
      top: 6px

  label
    position: absolute
    top: 18px
    left: 10px
    border-color: transparent
    color: #D5DBDB
    z-index: 0
    transition: all 300ms ease-out
    width: 100%
    transform-origin: top left

  &.alert
    margin-bottom: 30px
    .input
      border-radius: 6px 6px 0 0
      border-bottom: 1px solid red
    .alert
      opacity: 1
      transform: translateY(0)

button
  display: block
  background-color: #212F3C
  padding: 18px 10px
  color: white
  width: 100%
  border-radius: 6px
  font-size: 20px
  font-family: 'Helvetica', Arial, sans-serif
!

JS 

              
                window['submit-button'].addEventListener('click', e => {
  e.preventDefault()
  if (!window.email.checkValidity()) {
    document.querySelector(".input-wrapper").classList.add("alert")
  } else {
    document.querySelector(".input-wrapper").classList.remove("alert")
  }
})
!
999px

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