The first challenge, was something which I was thinking about a lot these days. The next one is actually a well known common task, but it is still difficult. In every project we have different types of layouts. Of course there are some patterns. The idea today is to implement them with pure CSS.
I'm currently working on OrganicCSS - a micro framework based on atomic CSS concept. I'm thinking a lot for name conventions, classes and of course mixins. I decided to combine three mixins in a file called _box-model.scss. They will provide a shortcuts for margin, padding and border properties.