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                <div class="language-select-wrapper">
    <select class="language-select" id="language">
        <option value="ja">日本語</option>
        <option value="en">English</option>
        <option value="ko">한국어</option>

<p data-lang-key="lead01">こんにちは、世界!</p>
<p data-lang-key="lead02">私たちのウェブサイトへようこそ。</p>
<a href="contact.html" data-lang-key="contact">お問い合わせ</a>


                body {
    padding: 20px;

.language-select-wrapper {
    width: 200px;
    position: relative;

.language-select {
    appearance: none;
    -webkit-appearance: none;
    -moz-appearance: none;
    padding: 10px;
    width: 100%;
    border: 1px solid #ccc;
    border-radius: 5px;
    background-color: white;
    background-image: url('data:image/svg+xml;charset=US-ASCII,<svg xmlns="" viewBox="0 0 2048 2048"><path d="M0 0h2048L1024 1024z"/></svg>');
    background-repeat: no-repeat;
    background-position: right 10px center;
    background-size: 12px 12px;
    cursor: pointer;

.language-select:focus {
    outline: none;
    border-color: #007bff;

.language-select:hover {
    border-color: #007bff;


                // 言語データの準備
const languageData = {
    'en': {
        'lead01': 'Hello, World!',
        'lead02': 'Welcome to our website.',
        'contact': 'Contact us'
    'ja': {
        'lead01': 'こんにちは、世界!',
        'lead02': '私たちのウェブサイトへようこそ。',
        'contact': 'お問い合わせ'
    'ko': {
        'lead01': '안녕하세요, 세계!',
        'lead02': '우리 웹사이트에 오신 것을 환영합니다.',
        'contact': '문의하기'

// セレクトボックスのchangeイベント設定
const langs =  document.getElementById('language');
langs.addEventListener('change', (e) => {

// changeイベントで実行する関数
// セレクトボックスから渡された値と言語データのキーを元に
// それぞれのHTMLタグに翻訳したテキストを設定する。
const changeLanguage = function(lang) {
    let elements = document.querySelectorAll('[data-lang-key]');
    elements.forEach(function (element) {
        let key = element.getAttribute('data-lang-key');
        let text = languageData[lang][key];
        element.textContent = text;