This table stopped rendering in Jupyter Notebook version 5.6.0 on Python 3.7 (It still worked fine in April 2018, but I am not sure what version of Jupyter I had)

```
|             | $k$ (m/d) | $z_b$ (m) | $z_t$ | $c$ (days) |
|:-----------:|----------:|----------:|------:|-----------:|
|Aquifer 0    |    2      |     0     |   20  |            |
|Leaky Layer 1|           |    -10    |   0   |   500      |
|Aquifer 1    |    80     |    -30    |   -10 |            |

```

I know need to add something in the empty cells, so the following renders

```
|Layer        | $k$ (m/d) | $z_b$ (m) | $z_t$ | $c$ (days) |
|:-----------:|----------:|----------:|------:|-----------:|
|Aquifer 0    |    2      |     0     |   20  |    -       |
|Leaky Layer 1|    -      |    -10    |   0   |   500      |
|Aquifer 1    |    80     |    -30    |   -10 |   -        |

```

But the first column should be center-aligned and it is right-justified (the colons used to define how the columns align). 

Anybody know if things changed? Can we not have empty cells in tables anymore? How can we specify the alignment of columns?