<body>
  <h1 class="test">Başlık Metni</h1>
  <div class="contaienr">
    <p class=”text”>lorem ipsum dolor sit amet</p>
    <p class=”subtext”>lorem ipsum dolor sit amet</p>
  </div>
</body>

<style>
  body {font-size: 16px; }
  h1 {font-size: 1.8em;}
  .text{font-size:1.5em;}
  .subtext{font-size:1.5rem;}
</style>