C format length specifier not working correctly

Question

This is strange.

Code:

for(i=ncx-1;i>=0;i--)
{
    fprintf(stderr,"|%-21s|\n",clist[i].label);
}
fprintf(stderr,"0-2-4-6-8-0-2-4-6-8-0-2-4\n");

Output:

    |5g(²G)              |
    |5f(²F°)            |
    |5d(²D)              |
    |5s(²S)              |
    |5p(²P°)            |
    |4f(²F°)            |
    |4d(²D)              |
    |4s(²S)              |
    |4p(²P°)            |
    |3d(²D)              |
    |3s(²S)              |
    |3p(²P°)            |
    |2s(²S)              |
    |2p(²P°)            |
    |1s(²S)              |
    0-2-4-6-8-0-2-4-6-8-0-2-4

Why aren't these lining up correctly?

I've changed the length and it still doesn't line up correctly.

Thanks.