Design Guide
Here you get an overview of the topics that are treated here.
Layout
Accessibility
Colors
Navigation
Fonts
Icons
Buttons
Resources
Design Process
Design Guide
Breakpoints for different devices
Usage of grids
Usage of whitespace
Color deficiencies
Make your designs accessible

Tips for a great dark mode

Contrast checker
Usage of colors
Color psychology
Navigation elements for mobile
Navigation elements for desktop
Sans serif fonts
Serif fonts
Slab serif fonts
Font size and scaling
Avoid these typo errors
Contrast checker
How to build icons
Best practice tips
Old vs new
Usage of icons

Inspiration and free icon sets

Rules for buttons
Usage of buttons

When to use buttons or links