Some extensions may not need any CSS because they inherit styles from the page itself. However, you can add additional styling in the CSS box. This will be injected on the page through a <style> tag.

Note that CSS does not support field values, so if you want to use those in styling you can do it directly in the HTML via inline styles, e.g., <div class="banner" style="background-color: {{extension.color}}">.

.banner {
  color: white;
  padding: 10px;
  position: fixed;
  top: 0px;
  z-index: 100000000;
  width: 100%;
  text-align: center;
  height: 45px;
}

.banner a {
  text-decoration: underline;
  color: white;
}

body {
 margin-top: 45px;
}