How to get column-count working in css

Hi, I added the following to my css file:

```
table{
border-collapse:collapse;
margin-bottom:calc(2em + 2vw);
clear:both;
font-size:10pt;
column-width: 200px;
column-count:3;
}
```

I expect that the table gets split into three columns in the resulting pdf. I confirmed that the style itself works by applying it in the exact same table when rendered on Github.

But in the resulting PDF that markdown-pdf produces, the tables stays in one column only. What am I doing wrong?