refact: extract typography constants

src/design/typography.ts

@@ -0,0 +1,13 @@
+const FONT_OXYGEN = "Oxygen, sans-serif"
+const FONT_MONTSERRAT = "Montserrat, sans-serif"
+
+export const BASE_FONT_SIZE = 18
+export const BASE_LINE_HEIGHT = 25
+export const MODULAR_SCALE = 1.1487
+
+export const fontFamily = {
+  header: FONT_MONTSERRAT,
+  body: FONT_OXYGEN,
+}
+
+export default fontFamily