What i should write in the line 12 please?

[liberta1]

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[markkarnaukh]

Hi,

colspan=“0” tells the browser to span the cell to the last column of the column group (colgroup),
you need to add calspan in your first table-header-section:

<th colspan="2">Famous Monster by Birth Year</th>

and remove next empty table-header-section:

<th colspan="2"></th>

Just carefully read the instructions to the task!