If you download the annotated games as html files to view offline, you will normally lose the accompanying diagrams. If you wish to be able to follow the diagrams, follow these instructions:
1) Create a new folder (directory) called 'gif' (lower case essential) and make this folder the subfolder of the folder into which you have downloaded the annotated game(s) as html files.
2) Download the following zipped file diagram.zip.
3) Unzip the downloaded file 'diagram.zip' into the 'gif' folder you have created. There should be 26 files in it. You should now be able to view the diagrams offline.