The layout grid is a set of guide lines that elements snap to, so things stay aligned no matter what content fills your template.
Show the grid
Click the grid button in the Toolbar to show or hide the grid and its rulers.
Add a grid line
With the grid shown, click on a ruler to add a guide line: the top ruler adds a vertical line, the left ruler adds a horizontal one.
Move or edit a grid line
Drag a grid line to reposition it. To set an exact position or remove it, double-click the line directly on the ruler to open its editor, where you can type its position in pixels or Delete it.
Snapping
When you drag an element near a grid line, its edge snaps to the line. That keeps elements aligned to the same guides across every version of your design.