@pluginarch/create-parch/templates/app/src/index.css

this is way to create a ui project

body { font-family: Arial, sans-serif; }
    nav a { margin: 0 10px; text-decoration: none; color: blue; }
    .page { display: none; }
    .active { display: block; }
    html, body {
      height: 100%;
      margin: 0;
      display: flex;
      flex-direction: column;
    }