Left-align headers in Markdown table?

Markdown:

| Tables        | Are           | Cool  |
|:------------- |:-------------:| -----:|
| col 3 is      | right-aligned | $1600 |
| col 2 is      | centered      |   $12 |
| col 1 is      | left-aligned  |   $42 |
| zebra stripes | are neat      |    $1 |

Result:

Note that the colon (“:”) on the second row, and the second character is what worked to
The other option is to move the numbers to the left-most column (as below)

Amount | Items
------:|:-----
    20 | Wooden Boards
     5 | Old Parts

Try it on StackEdit.

It does not seem to work putting the —- line above the headers.