What is your understanding of 'reality'?
In the first place, when I began thinking about whether the world around us is solid, I began thinking to what extent we, as human beings are solid. However, I guess that is more complicated than whether tables are solid, partly due to the aging processes and also, because we are made up mostly of water. So, thinking about tables makes it a bit easier as a starting point, although I do think it is worth considering whether we are more solid or less solid than tables in terms of firmness. I actually think that tables are firmer than human beings because they are not part of nature, and do not get sick and die.
But, if you think about the solidity or firmness of tables, it partly comes down to them not being liquid, and they don't evaporate. If we leave a table in the room overnight, we can rely on it being there, in the same shape in the morning. However, I can remember one table I had collapsing when I put about 200 books on it, but that probably didn't mean that it was not solid in the way of physical existence, because it is not as if it just disappeared.
I think being solid is also about being in the three dimensional world, although I think that there are probably about 5 or 6 dimensions, or even more. But, thinking about objects is about being in three dimensions. So, we could say that the e books we read are less solid than the paper ones. Going back to tables though I think that existing and being surrounded by space is important. It comes down to existing as matter and being a structure which ensures for a substantive amount of time. I am not sure that they are absolutely solid, but I think that they are more solid than living parts of nature, because they are not subject to impermanence to the extent that living beings are, and are not mortal.