Length of input filed in table

I added an input field to a column of table to get the input value. The width of columns in the empty table was depend on the column title. So when I added an empty row, the length of input field was too long, it covered two columns. How to make it look better? I mean the length of input field is the same as the width of the column, just as what it is in the GUI.

Thanks and Best Regards,

Jun