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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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Packages

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HTML 

              
                <label>
	<input class="js-check" type="radio" name="rs" value="1" onclick="formSwitch()" >特にない
</label>

<label>
  <input class="js-check" type="radio" name="rs" value="1" onclick="formSwitch()">好きな音楽のジャンル
</label>

<span id="sample">
  
<div class="selecter">
  <select id="changeSelect" name="hoge" onchange="entryChange2();">
    <option value="select1">ジャンルを選んでください</option>
    <option value="select2">ロック</option>
    <option value="select3">ジャズ</option>
    <option value="select4">ポップス</option>
    <option value="select5">クラシック</option>
    <option value="select6">ラテン</option>
   </select>
</div>
  
</span>

<div id="Box">
  <p>『ロック』の発祥は1950年代と言われています。アメリカに奴隷として連れてこられた黒人たちのアフリカ系黒人音楽が起源らしいです。</p>
</div>

<div id="Box2">
  <p>『ジャズ』は、19世紀末から20世紀初頭にかけて、アメリカのニューオリーンズで西洋楽器を用いたヨーロッパ音楽の技術と独特なリズムの黒人音楽が融合したことにより生まれたとされます。</p>
</div>

<div id="Box3">
  <p>『ポップス』は1950〜60年代に西洋でロックの派生として現代的形態で始まったポピュラー音楽です。</p>
</div>

<div id="Box4">
  <p>『クラシック』の語源はラテン語のクラスにあり、直訳すると「古典音楽」です。一流・最高という意味もあります。</p>
</div>

<div id="Box5">
  <p>『ラテン』は、中南米発祥の音楽の総称で中南米とカリブ海地域のラテン系の民族音楽のことを言います。</p>
</div>
!

CSS 

              
                .selecter select {
  /* styling */
  background-color: white;
  border: thin solid #E5E5E5;
  border-radius: 4px;
  display: inline-block;
  font: inherit;
  line-height: 1.5em;
  padding: 0.5em 3.5em 0.5em 1em;
  cursor: pointer;
  /* reset */
  margin: 0;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
  -webkit-appearance: none;
  -moz-appearance: none;
  background-image: linear-gradient(45deg, transparent 50%, white 50%), linear-gradient(135deg, white 50%, transparent 50%), linear-gradient(to right, #E07581, #E07581);
  background-position: calc(100% - 20px) calc(1em + 2px), calc(100% - 15px) calc(1em + 2px), 100% 0;
  background-size: 5px 5px, 5px 5px, 2.5em 2.5em;
  background-repeat: no-repeat;
}

.c-selecter select:focus {
  background-image: linear-gradient(45deg, white 50%, transparent 50%), linear-gradient(135deg, transparent 50%, white 50%), linear-gradient(to right, gray, gray);
  background-position: calc(100% - 15px) 1em, calc(100% - 20px) 1em, 100% 0;
  background-size: 5px 5px, 5px 5px, 2.5em 2.5em;
  background-repeat: no-repeat;
  border-color: grey;
  outline: 0;
}

.js-check{
  margin-bottom:15px
}
!

JS 

              
                var selecterBox = document.getElementById('sample');
var selecter = document.getElementById('changeSelect');
var item1 = document.getElementById('Box');
var item2 = document.getElementById('Box2');
var item3 = document.getElementById('Box3');
var item4 = document.getElementById('Box4');
var item5 = document.getElementById('Box5');
selecterBox.style.display = "none";
item1.style.display = "none";
item2.style.display = "none";
item3.style.display = "none";
item4.style.display = "none";
item5.style.display = "none";

    function formSwitch() {
        check = document.getElementsByClassName('js-check')
        if (check[0].checked) {
            selecterBox.style.display = "none";
            item1.style.display = "none";
            item2.style.display = "none";
            item3.style.display = "none";
            item4.style.display = "none";
            item5.style.display = "none";
            selecter.selectedIndex = 0;

        } else if (check[1].checked) {
            selecterBox.style.display = "block";

        } else {
            selecterBox.style.display = "none";
        }
    }
    window.addEventListener('load', formSwitch());

function entryChange2(){
    if(document.getElementById('changeSelect')){
    id = document.getElementById('changeSelect').value;

    if(id == 'select2'){
        item1.style.display = "block";
        item2.style.display = "none";
        item3.style.display = "none";
        item4.style.display = "none";
        item5.style.display = "none";
    }
    else if(id == 'select3'){
        item1.style.display = "none";
        item2.style.display = "block";
        item3.style.display = "none";
        item4.style.display = "none";
        item5.style.display = "none";
    }
    else if(id == 'select4'){
        item1.style.display = "none";
        item2.style.display = "none";
        item3.style.display = "block";
        item4.style.display = "none";
        item5.style.display = "none";
    }
    else if(id == 'select5'){
        item1.style.display = "none";
        item2.style.display = "none";
        item3.style.display = "none";
        item4.style.display = "block";
        item5.style.display = "none";
    }
     else if(id == 'select6'){
        item1.style.display = "none";
        item2.style.display = "none";
        item3.style.display = "none";
        item4.style.display = "none";
        item5.style.display = "block";
    }
    else{
        item1.style.display = "none";
        item2.style.display = "none";
        item3.style.display = "none";
        item4.style.display = "none";
        item5.style.display = "none";
    }
}
}
!
999px

Console