* {
      box-sizing: border-box;
    }

    body {
      margin: 0;
      font-family: sans-serif;
      line-height: 1.5;
      padding: 1rem;
    }

    .container {
      max-width: 800px;
      margin: auto;
    }

    iframe[src*="youtube.com"] {
      width: 100%;
      aspect-ratio: 9 / 16;
      border: 0;
      display: block;
    }

    img {
      max-width: 100%;
      height: auto;
    }

    h1 {
      font-size: 2rem;
    }

    @media (max-width: 768px) {
      h1 {
        font-size: 1.5rem;
      }
    }