隣接セレクタで作るリストデザイン

<!DOCTYPE html>
<html lang="ja">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>ul{
  border: 1px solid #999999;
  margin: 10px 20px;
}

list {
  border: 1px solid #999999;
  margin: 10px 20px;
}

.list-item {
  list-style-type: none;
  padding: 10px 20px;
}

.list-item + .list-item {
  border-top: 1px solid #999999;
}</style>
</head>
<body>
<ul>
<li class="list-item">感染爆発の重大局面</li>
<li class="list-item">アベノマスク</li>
<li class="list-item">東京アラート</li>
<li class="list-item">ウィズコロナ宣言</li>
</ul>
<script>
</script>
</body>
</html>

ul{
  border: 1px solid #999999;
  margin: 10px 20px;
}

list {
  border: 1px solid #999999;
  margin: 10px 20px;
}

.list-item {
  list-style-type: none;
  padding: 10px 20px;
}

.list-item + .list-item {
  border-top: 1px solid #999999;
}