Improper cells margin collapsing

[Massimiliano Filacchioni]

Hello,

overflow: auto CSS declaration for .observablehq selector in dataflow index.html prevents proper cells margin collapsing. So, for example, if you create multiple consecutive md cells, each containing a couple of paragraphs, the gap between these cells will be much bigger than the one between internal paragraphs, and the resulting formatting will feel unnatural.

Removing the above declaration seems to solve the problem. at least for the notebooks I'm experimenting with.