This feature is accessed from the Layout Tab in Theme Builder 3.0 and above by clicking one of the panels shown in the layout preview.
The menus allow you to quickly customise the following attributes of the panel (click a link for more details):
The chequerboard pattern depicts the canvas. It enables you to quickly see whether a panel is transparent or not:
You will also see one or two feint dotted lines in the preview which indicate the amount of padding or margin spacing applied to the panel:
There are three buttons at the bottom-right of the panel editor:
This button allows you to edit the Panel Content (wiki notation and other panel-specific settings).
When you've finished making changes to the panel, click "Apply" to update the layout preview.
This does not save the changes to the layout, it merely updates the layout preview above the panel editor. You must save the changes using the Save button on the Toolbar.
To cancel your visual changes (those made using the menus), click the "Cancel" button.
You have to add Custom CSS using the CSS Tab.
To set the margins and padding of the title panel for example, you would use:
That would set the margin above the panel to 5 pixels and add 10 pixes of padding to the left side of the panel.
For more information on the classes used to represent panels, see Panel Classes and IDs.