The guideline helps ensure that typography is always in harmony with the overall visual design.
A selection of typeface styles are allocated throughout the user interface as follows. Set system defaults and conduct design activities using the design typeface styles. To respect user typeface choices while preserving the distinction afforded to each typographic category, implement the design using the corresponding system typeface styles.
Menus - Menu bar, Popup menus
Content Title - Category title, Panel popups title
Content Header - Section headers
Content Body 1 - Text content, Icon grid items, List items
Content Body 2 - Captions , tooltips
Properties and Tools - Property panel, Toolbar, Status bar
The text color and background color can be varied to provide additional hierarchical hints (e.g. selected text). However, the contrast between the text and background color must be sufficient to preserve legibility of the text.
Unless the content is long-form text like a book or a report, try to keep line lengths to no more than about eight to ten words per line. For typographic categories that use an all caps typeface, try to keep line lengths to no more than about three to four words per line.
When the visual design calls for an area of exceptional focus, a larger typeface size may be used. For a significantly larger typeface use a Light typeface weight to keep the stroke width similar to other typeface styles throughout the interface . All other typeface characteristics for the typographic category should be maintained. For such typeface exceptions to be effective, they must be rare.