Notification Page with React and SaSS

Wow! Third challenge is complete. This challenge was not difficult, yet I discovered that I didn't know how to set up the type of projects I work in (now I know). I have a few questions:

• Is the structure of the project useful?
• I try to organize the style system by creating variables for colors and mixins, is it how current web development projects work, or am I lost on this?
• What can I do when column width doesn't work as expected? It was pretty difficult to adjust components with this systems without using bad practices such as forced padding or margin.