You can customize the OmniPlan HTML reports by going to OmniPlan > Preferences, then select the HTML tab. To create a new template, select any of the built-in templates, then click the Action pop-up menu (looks like a gear) and select Edit a Copy.
A save dialog will appear for you to specify the destination of your new HTML Template. After creating the folder of HTML and CSS files, you can edit the HTML and CSS files in the new template folder using your text editor of choice.
