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                 <header class="globalHeader">
    <h1 id="globalHeader__heading">JavaScript初学者講座</h1>
    <nav class="globalHeader__navigation">
      <ul class="globalHeader__navigationList">
        <li class="globalHeader__navigationItem globalHeader__navigationItem--about"><a href="" class="globalHeader__navigationLink">講座概要</a></li>
        <li class="globalHeader__navigationItem globalHeader__navigationItem--teacher"><a href="" class="globalHeader__navigationLink">講師紹介</a></li>
        <li class="globalHeader__navigationItem globalHeader__navigationItem--contact"><a href="" class="globalHeader__navigationLink">お問い合わせ</a></li>


                #globalHeader__heading {
  margin-left: 32px;

.globalHeader__navigationList {
  display: flex;

.globalHeader__navigationItem {
  list-style: none;
  margin-right: 12px;


                // 挿入先の要素を取得
const list = document.querySelector(".globalHeader__navigationList");

// liタグを生成してclassを付与
const listItem = document.createElement("li");
listItem.classList.add("globalHeader__navigationItem", "globalHeader__navigationItem--contact");

// aタグを生成してclassの付与とテキストの挿入、hrefの付与
const listItemLink = document.createElement("a");
listItemLink.className = "globalHeader__navigationLink";
listItemLink.innerText = "ブログ概要";
listItemLink.href = "#";

// liにaタグを挿入

// 挿入先のリストにタグを挿入