Код IT Загрузка примера кода…

HTML main.html 
<!DOCTYPE html>
<html lang="ru">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Fade in</title>
  <style>
    *, *::before, *::after { box-sizing: border-box; }
    body {
      margin: 0;
      min-height: 100dvh;
      display: grid;
      place-items: center;
      font-family: system-ui, sans-serif;
      background: #eef2ff;
    }
    .card {
      padding: 1.5rem 2rem;
      background: #fff;
      border-radius: 12px;
      box-shadow: 0 8px 24px rgba(0, 0, 0, 0.08);
      animation: fadeIn 0.6s ease forwards;
    }
    @keyframes fadeIn {
      from { opacity: 0; }
      to   { opacity: 1; }
    }
  </style>
</head>
<body>
  <article class="card">
    <h1 style="margin: 0 0 0.5rem; font-size: 1.25rem;">Привет!</h1>
    <p style="margin: 0; color: #64748b;">Карточка плавно появилась.</p>
  </article>
</body>
</html>
<!DOCTYPE html>
<html lang="ru">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Fade in</title>
  <style>
    *, *::before, *::after { box-sizing: border-box; }
    body {
      margin: 0;
      min-height: 100dvh;
      display: grid;
      place-items: center;
      font-family: system-ui, sans-serif;
      background: #eef2ff;
    }
    .card {
      padding: 1.5rem 2rem;
      background: #fff;
      border-radius: 12px;
      box-shadow: 0 8px 24px rgba(0, 0, 0, 0.08);
      animation: fadeIn 0.6s ease forwards;
    }
    @keyframes fadeIn {
      from { opacity: 0; }
      to   { opacity: 1; }
    }
  </style>
</head>
<body>
  <article class="card">
    <h1 style="margin: 0 0 0.5rem; font-size: 1.25rem;">Привет!</h1>
    <p style="margin: 0; color: #64748b;">Карточка плавно появилась.</p>
  </article>
</body>
</html>