You can call up the source code by clicking the 'here' link below the board twice, and pressing the 'Source code' button that will then appear under the legenda for the piece list.
Beware that the buttons for changing the piece and board theme on this page are not part of the Diagram, but additional elements included in the HTML page, which manipulate the Diagram's settings and then re-initialize it. But you can see how this is done by using the 'Page Source' item in the context menu of your browser, which shows everything that is on the page, including the Diagram definition.
You can call up the source code by clicking the 'here' link below the board twice, and pressing the 'Source code' button that will then appear under the legenda for the piece list.
Beware that the buttons for changing the piece and board theme on this page are not part of the Diagram, but additional elements included in the HTML page, which manipulate the Diagram's settings and then re-initialize it. But you can see how this is done by using the 'Page Source' item in the context menu of your browser, which shows everything that is on the page, including the Diagram definition.