The combination of nth-child and cicada principle is a clever technique used for faking the randomisation of patterns.

Printable Sketch Sheets for Design Wireframing

In Material Design every part of the system has a precise goal - because the content is the center of the attention, not the chrome that frames it - and shadows are not an exception. They are not fancy elements meant to give fluffiness to an otherwise flat UI, but a key element to make the user immediately understand the structure of the app they are launching for the first time.

When I stumbled across it, I couldn't get it out of my head. I recited the acronym on my bike ride home. I scribbled it on whiteboards around our conference rooms. I was head over heels. HEART is a framework for measuring and improving user experience, and each letter stands for a different user experience metric: Happiness, Engagement, Adoption, Retention, and Task Success.

What gets written on the Internet about the design of apps, web sites, icons, identity systems and digital experiences of all kinds is almost always written by people who are professional designers first and foremost. We don't have a class (or even a sub-class) of writers who are actively engaged and uncompromised in thinking about what makes for good design and why.