Components Share the Same Properties Regardless of Reference Type
You noticed that the journal article reference type has a comma in front of Year derived. For internet documents you want a period to appear in front of the year. If you change the comma to a period for internet documents in the field Punctuation before for the Year derived component, you'll notice that the period appears for journal articles, too.
The journal article and internet document reference types both use the same Year derived component.
Create a copy of the component. On the Component menu, click Duplicate to create a component that you can then edit so that it uses different formatting.
If you're not sure if a component has been used by other reference types, select the component from the list of components on the left side of the Citation Style Editor. Click the Delete button. A warning will appear that shows where else the component was used. Click Cancel.