How to center Form on page?

How to place Form on page’s center? I.e. align to middle vertically and horizontaly on page.

Use complex layout with spacer elements to the left and to the right and set the needed gravity to these parts.

Spacer elements are empty views with no content, but they will take space.

Gravity shows how many times the cell should be bigger than the cells in the same row or column.

http://webix.com/snippet/807f86f9