I found this in the ServiceDesk Customization Guide.  I haven't gotten around to customizing fonts, but perhaps it helps you.  It explains how to change existing themes, how to create new themes, and how to make changes to form text.  It uses the customer sat survey as an example.

Change the Theme and Template for a Form
Themes in Symantec Workflow dictate component control styles (like font attributes), dialog box (form) size, border width and style, and background images. Templates in Symantec Workflow dictate more general features, such as components for pieces of data you want standard across the process (for example, the ticket header information in Incident Management), and the Incident Management logo.

You can modify form appearance by selecting from a range of theme and template styles provided, or create your own. Note that if you modify a theme or template that came with ServiceDesk, the changes impact all forms that use that theme or template. If a new theme or template is created, it is necessary to manually apply the theme or template to its respective form.

These instructions explain working with themes and templates using the customer service satisfaction survey as an example.

To change the theme and template of the customer service satisfation survey
1. In Symantec Workflow, open the SD.CustomerServiceSurvey project.
2. Double-click the “Customer Service Survey Main Form” Form Builder component. This opens the Web Form Editor.
3. Click the folder icon on the top left. (This is the Select Theme icon.) This opens a Select Theme and Templates window. You can modify the theme listed in the window by clicking the Edit Selected Theme button and making the desired chanages. You can add a new theme by clicking the Edit Project Themes button, then selecting Add to access a blank theme to configure.  You can change the theme selection by simply selecting a different theme and clicking OK (which is necessary when you create a new theme in order to apply it) You can also change the templates by going into the Templates tab on the Select Theme and Templates window. “Service Desk” is the template that the process uses. You can edit this template by selecting the template and clicking on the Edit button on the right. If you want to add a new template, click on New to add a new template, then configure the template. Note: A form can use more than one template. It depends on how you want to present the data on the form.

To create a new theme using the Composer Theme Editor
1. New themes are created using a utility included with Symantec Workflow. From the Start menu, select > All Programs > Altiris > Workflow Designer > Tools > Composer Theme Editor.
2. Click the New icon to start a new theme. When the theme is saved, it automatically defaults to the directory where themes are browsed to when editing a form. For
further information on building themes, consult the Symantec Workflow documentation.
3. New themes will need to be applied manually to the respective forms.

To create a new template
1. New templates are created within the form editor itself by right-clicking the form and selecting Templates > New Template. 
Change Task Assingee
In Dialog Workflow components, the Task Assignments tab contains the user/group/ organization to whom the task is initially assigned. You can change this assignment as desired by opening up the respective Dialog Workflow component, scrolling down the Task Assignments tab, and updating the Assigments section.

Make Changes to Form Text
This section explains how to make changes to existing text using the customer satisfaction survey as an example.

To change text in the customer service satisfation survey
1. In Symantec Workflow, open the SD.CustomerServiceSurvey project.
2. Double-click the “Customer Service Survey Main Form” Form Builder component. This opens the Web Form Editor.
3. Change the “Thank you” message at the top by double-clicking that component and changing the content of the Text field.
4. Change text style using the options under Look and Feel.
5. To adjust the size of a text field, simply click on the text field in the Web Form Editor and use the mouse to resize. You can also drag and drop existing form fields to
reorganize the content.

Does this help?

Mclemson, Thanks for responding,

I want to change the look of the portal, that is the blue/gray bars and white text titles etc of the web parts that are added. The customization guide is talking about the themes etc of the form dialogs etc. that are presented typically outside the portal, i.e. survey, approvals etc. see attachment.