How to set different styles on one element for each device. (responsive)

@arthuralmeidap can you tell guide me how to set style different style for each device. I use the mobile-first strategy.

For example to set a different background on mobile and desktop devices.

mediaCondition: 'min-width',

var deviceManagerConfig = { devices: [ { name: 'Desktop', width: '', widthMedia:'768px' }, { name: 'Tablet', width: '768px', widthMedia:'320px' }, { name: 'Mobile', width: '320px', widthMedia:'0px' } ] };