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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>

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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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 

              
                <h3>CSSのtext-decorationで下線を引く方法</h3>
<p class="underline-text-decoration">一番シンプルな`text-decoration`で下線を引く方法。</p>
<p class="through-text-decoration">`text-decoration`で取り消し線を引く</p>

<h3>borderで点線やドットの下線を作る方法</h3>
<p class="border-solid">CSSの`border`プロパティで下線を引く。</p>
<p class="border-dotted">CSSの`border`プロパティで点線を引く。</p>
<p class="border-dashed">CSSの`border`プロパティで点線を引くその２。</p>

<h3>borderの長さと文字と同じ長さにする</h3>
<p class="border-inline">CSSの`border`プロパティで下線を引く。</p>

<h3>borderの長さを指定していろんなサイズの下線を引く</h3>
<p class="border-half">CSSの`border`で半分サイズの下線を引く</p>
<br>
<p class="border-30">CSSの`border`で長さ30pxの下線を引く</p>
<br>
<p class="border-30-center">CSSの`border`で下線を中央に配置する</p>

<h3>borderでマーカーっぽいアンダーラインを作る</h3>
<p class="border-marker">CSSの`border`でマーカーっぽい下線を引く</p>
<p>CSSで<span class="border-marker">この文字だけ</span>マーカっぽい下線を引く</p>

<h3>backgroundでマーカー風のおしゃれな下線を作る方法</h3>
<p class="box-half">CSSの`background`で半分サイズの下線を引く</p>
<br>
<p class="box-30">CSSの`background`で長さ30pxの下線を引く</p>
<br>
<p class="box-30-center">CSSの`background`で下線を中央に配置する</p>

<h3>backgroundでマーカーっぽいおしゃれな下線を作る</h3>
<p class="background-marker">CSSの`background`でマーカーっぽい下線を引く</p>
<p>CSSで<span class="background-marker">この文字だけ</span>マーカっぽい下線を引く</p>
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CSS 

              
                body {
  padding: 50px;
}
h3 {
  margin-top: 100px;
}

.underline-text-decoration {
  text-decoration: underline;
}
.through-text-decoration {
  text-decoration: line-through;
}

.border-solid {
  border-bottom: 1px solid #000;
}
.border-dotted {
  border-bottom: 1px dotted #000;
}
.border-dashed {
  border-bottom: 1px dashed #000;
}

.border-inline {
  display: inline-block;
  border-bottom: 1px solid #000;
}

.border-half,
.border-30,
.border-marker,
.border-30-center {
  display: inline-block;
  position: relative;
}
.border-half::after {
  content: "";
  position: absolute;
  bottom: -5px;
  left: 0;
  width: 50%;
  border-bottom: 2px solid #000;
}
.border-30::after {
  content: "";
  position: absolute;
  bottom: -10px;
  left: 0;
  width: 30px;
  border-bottom: 5px solid #2445da;
}
.border-30-center::after {
  content: "";
  position: absolute;
  bottom: -15px;
  left: 50%;
  transform: translateX(-49%);
  width: 30px;
  border-bottom: 5px solid #da2424;
}
.border-marker::after {
  content: "";
  position: absolute;
  bottom: 0px;
  left: 0;
  width: 100%;
  border-bottom: 10px solid #ffea6d;
  z-index: -1;
}


.box-half,
.box-30,
.box-30-center {
  display: inline-block;
  position: relative;
}
.box-half::after {
  content: "";
  position: absolute;
  bottom: -5px;
  left: 0;
  width: 50%;
  height: 5px;
  background-color: #000;
}
.box-30::after {
  content: "";
  position: absolute;
  bottom: -10px;
  left: 0;
  width: 30px;
  height: 5px;
  background-color: #2445da;
}
.box-30-center::after {
  content: "";
  position: absolute;
  bottom: -15px;
  left: 50%;
  transform: translateX(-49%);
  width: 30px;
  height: 5px;
  background-color: #da2424;
}

.background-marker {
  display: inline-block;
  position: relative;
}
.background-marker::after {
  content: "";
  position: absolute;
  bottom: 0px;
  left: 0;
  width: 100%;
  height: 10px;
  background-color: #ffea6d;
  z-index: -1;
}
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JS
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