How font size works in Geckoboard
Geckoboard automatically sizes fonts to optimize readability across different widget sizes. Font sizes cannot be manually adjusted.
Using the Text widget or Custom Widgets API
If you're using the Text widget data source, Markdown formatting is available to create visual hierarchy with headings and other text styles.
If you're using the legacy Custom Widgets API, you can learn more about HTML tags and attributes available to style or customize your text.