table-layout: auto follows the content

a	a much longer second column	c
1	2	3

table-layout: fixed shares the space evenly

a	a much longer second column	c
1	2	3

table-layout: fixed keeps a declared first column

120px

the rest splits evenly

c

border-spacing: 0 and 8px 16px

no	gap
at	all

wide	gaps
both	axes