body{
  margin-top: 50px;
}

body::before{
  content: 'Sitio de Pruebas';
  display: flex;
  width: 100%;
  height: 50px;
  background-color: #E00000;
  color: #fff;
  justify-content: center;
  align-items: center;
  font-weight: bolder;
  font-size: 16px;
  text-transform: uppercase;
  position: fixed;
  top: 0;
  z-index: 1000;
  border-top: 2px dashed #fff;
  border-bottom: 2px dashed #fff;
}