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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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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

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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.

All packages are different, so refer to their docs for how they work.

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HTML 

              
                ol
 li.half-pixel-after Generate content & transform: scale(.5)
 li.half-pixel-img border-image stretch & svg
 li.half-pixel-background-svg background: url(svg)
 li.half-pixel-original half pixel support (works on Safari) 
 li.half-pixel-background background: linear-gradient (visible when dpr gte 2)

div(style="text-align:center")
  h2 圆角细线
  .avatar-box
    img(src="http://ww3.sinaimg.cn/large/6eba2496gw1f3vtj57hjij20pq0pqwf3.jpg", width="60")
!

CSS 

              
                @import "bourbon";


@mixin hairline-radius($border-color: #d9d9d9, $radius: 0) {
  position: relative;
  &::after{
    content: '';
    @include position(absolute, -50%);
    border: solid 1px $border-color;
    transform: scale(.5);
    transform-origin: center center;
    pointer-events: none;
    border-radius: $radius*2;
  }
}

$border-color: #aaa;
body { color: #444; }
li {
  margin: 10px; padding: 5px 10px;
}
.half-pixel {
  // https://github.com/huanghuiquan/1px
  &-after {
    position: relative;
    &::after {
      content: '';
      @include position(absolute, null 0 0 0);
      border-bottom: solid 1px $border-color;
      transform: scaleY(.5);
      transform-origin: 0 100%;
    }
  }
  &-background {
    background: linear-gradient(transparent 50%, $border-color 50%) no-repeat left bottom;
    background-size: 100% 1px;
  }
  &-background-svg {
    background: url('data:image/svg+xml,\
      <svg xmlns="http://www.w3.org/2000/svg" width="1" height="1">\
      <rect width="1" height="0.5" fill="#{$border-color}"/>\
      </svg>') repeat-x bottom;
  }
  &-img {
    border-width: 0 0 1px;
    border-image: url('data:image/svg+xml,\
    <svg xmlns="http://www.w3.org/2000/svg" width="10" height="40">\
      <rect width="10" height="10" fill="#{$border-color}" />\
      <rect y="30" width="10" height="10" fill="#{$border-color}" />\
    </svg>') 20 0 stretch;
  }
  // https://github.com/maxzhang/maxzhang.github.com/issues/4#issuecomment-69145019
  &-original {
    border-bottom: solid 1px $border-color;
    border-width: 0.5px;
  }
}
// http://stackoverflow.com/questions/8640521/can-you-have-a-0-5px-border-on-a-retina-display/25910251#25910251


.avatar-box {
  padding: 2px; display: inline-block;
  @include hairline-radius(#b2b2b2, 5px);
}
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JS
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999px

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