When you create a custom html module, you have lots of variations, to set quickly design your website. There are several module classes you can use and you can combine them as well!

For instance:

bg-primary sets the background to the primary color
bg-secondary sets the background to the secondary color

ETC

you can add the following options as well:

text-white

you can add these in the module-class field for your modules. you can find this field under the advanced tab.