function colourshade(texte,ared,agreen,ablue,zred,zgreen,zblue) {
  var i;
  var stepred,stepgreen,stepblue;
  var ired,igreen,iblue;

  ired=ared;
  igreen=agreen;
  iblue=ablue;

  stepred=((zred-ared)/texte.length);
  stepgreen=((zgreen-agreen)/texte.length);
  stepblue=((zblue-ablue)/texte.length);

  for (i=0;i<texte.length;i++) {
    ired=ired+stepred;
    igreen=igreen+stepgreen;
    iblue=iblue+stepblue;
    document.write ('<font color="rgb('+ired+','+igreen+','+iblue+')">' + texte.substring (i,i+1) + '</font>');
  }

}