kafka-ui/kafka-ui-react-app/src/components/App.scss

$header-height: 52px;
$navbar-width: 250px;

.Layout {
  &__header {
    box-shadow: 0 0.46875rem 2.1875rem rgba(4,9,20,0.03),
      0 0.9375rem 1.40625rem rgba(4,9,20,0.03),
      0 0.25rem 0.53125rem rgba(4,9,20,0.05),
      0 0.125rem 0.1875rem rgba(4,9,20,0.03);
    z-index: 31;
  }

  &__container {
    margin-top: $header-height;
    margin-left: $navbar-width;
  }

  &__navbar {
    width: $navbar-width;
    display: flex;
    flex-direction: column;
    box-shadow: 7px 0 60px rgba(0,0,0,0.05);
    position: fixed;
    top: $header-height;
    left: 0;
    bottom: 0;
    padding: 20px 20px;

  }
}