code: function cover () {
    var SL = ', 100%, 85%';
    var bgc = 'linear-gradient(to left bottom, ' +
    "hsl(" + (Math.floor(Math.random() * 255) + SL) + ") 0%," +
    "hsl(" + (Math.floor(Math.random() * 255) + SL) + ") 100%)";
  
    return "<section class=\"cover\" style=\"background: " + bgc + "\">" +
      '<div class="cover-main"></div>' +
      '<div class="mask"></div>' +
    '</section>'
  }
docs: Cover Page