anchor.diff:  
     // - - - - - - - - - - - - - - - - - - - - - - - -
   
  -  var makeDiffFilenames = function(diffs) {
  +  const makeDiffFilenames = (diffs) => {
       // align-right is for diff toggling added/deleted line counts
       return '' +
         '<table align="right">' +
  
positive.code:   // refresh [<] tag [>]
    //-----------------------------------------
  
    var refreshTagControls = function() {
      var colour = param.lights[param.nowTag - 1].colour;
      var minTag = 1;
      var maxTag = param.lights.length;
      var hasPrevTag = minTag < param.nowTag;
      var hasNextTag =          param.nowTag < maxTag;
  
      $('#now-tag-number')
        .removeClass()
  
negative.code:   // refresh files
    //-----------------------------------------
  
    const refreshFiles = () => {
      const diffContent = $('#diff-content');
      const diffFilenames = $('#diff-filenames');
      diffFilenames.html(makeDiffFilenames(param.diffs));
      resetFilenameAddedDeletedLineCountHandlers();
      diffContent.html(makeDiffContent(param.diffs));
  