Source Serif 4 and Source Sans 3
Headings in Source Serif 4, body text in Source Sans 3.
Why it works
Source Serif 4 was built to match Source Sans 3, so the serif headline and the sans paragraph share the same proportions.
Headings in Source Serif 4, body text in Source Sans 3.
Source Serif 4 was built to match Source Sans 3, so the serif headline and the sans paragraph share the same proportions.