Menu Style

Make the menus bigger or smaller, pick the font, change the accent colour, and control animations and backgrounds.

Menus
The Settings page (the Settings tab at the top of the Sour Client menu): sections down the left, their rows on the right.
The Settings page (the Settings tab at the top of the Sour Client menu): sections down the left, their rows on the right.

Menu size

Menu Scale sets how big Sour's own menus draw: Mods, Settings, Resource Packs, Profiles, Cosmetics, the HUD editor, the title and Esc menus and the server and world lists. Auto is the size they have always been; Small, Large and Huge are even 15% steps either side of Normal and stop at the largest size your window fits. Custom takes an exact percentage from 25 to 200.

Turn on Set Per Menu to give individual menus their own size, for example a bigger HUD editor and a smaller server list.

Font

OptionLooks like
Sour Client fontSour's bundled typeface everywhere.
MixMinecraft's font for list and row text, Sour's in headings and controls.
Minecraft fontMinecraft's font for all body text in Sour menus; resource-pack fonts apply. Headings stay on Sour's display type.

UI Font Size scales all menu text.

Accent, animations and backgrounds