Just to preface, the DOM structure and classes are subject to change. We don’t officially support CSS customizations, so proceed at your own peril. 
Not sure what you mean as there is a hierarchy defined in the DOM structure. There’s typically a main div with the class .tile as well as a class representing the type of device (eg. .switch, .switch-level, .button) then under that are divs/spans for holding key tile information eg. .title, .main-content, .footer. Inside your .main-content you’ll typically find the .icon. Inside the .footer you’ll typically find supplemental information and extra actions. Again, this DOM structure may change with future updates.
I believe some people are using third-party browser plugins to accomplish this. We aren’t officially supporting this since we might change the structure/classes in the future, so I don’t have any particular guidance.
If there is a specific thing you’d like to see customized, it would be awesome if you could share examples as it might be something that could be built into the core customization engine! 