[cssgrid](https://github.com/elcritch/cssgrid) now supports basic auto-flow working with either rows _or_ columns. Auto-flow is how items that don't have a set position get positioned. In the examples below you can see two large blocks are fixed at the 1//2 column and the 5//6 column (darker blue). Then non-fixed nodes are flowed around the fixed ones. I've started using pixie to draw images in the tests.
Unfortunately css-grid "dense" mode currently isn't supported, but wouldn't be too hard to implement in the future. Another limitation currently is that mixed sized non-fixed nodes aren't handled -- yet it's next on the list. auto-flow-column: auto-flow-row:
