Bold buttons

.ck-button.ck-button--bold--blue .ck-button.ck-button--bold--green

Simple buttons

.ck-button.ck-button--simple--default .ck-button.ck-button--simple--blue

Tertiary buttons

.ck-button.ck-button--tertiary--default .ck-button.ck-button--tertiary--blue

On dark backgrounds

.ck-button.ck-button-on-dark .ck-button.ck-button-on-dark

Icon buttons

Left aligned

Right aligned

Both

Icon only