In response to user feedback, we’re adding a vertical ruler in Google Docs on the web that will help you manipulate tables and control the margins in headers and footers.

Better table management with new vertical ruler 

When you’re using a table, you’ll see your table structure highlighted in a vertical ruler on the left side of the screen. The vertical ruler matches the horizontal ruler, which already exists and is a popular way to control cell width and margins.

You can use the ruler to change the height of rows in the table. When you do so, you’ll see a guide telling you the specific height of the row so you can quickly format it to the specific size you want. You can also use it to control the vertical margins in headers and footers (see more details below).