You can reposition objects accurately by using the nudge facility. This will move objects one pixel at a time in any direction by using the appropriate arrow keys. This can be invaluable in fine- tuning the position of objects so that they align with other elements on the page.
Hold down the Shift key and click on all of the objects you want to nudge. A bounding box will surround each object.
Press the arrow key: Up (or NumPad 8), Down (or NumPad 2), Left (or NumPad 4), Right (or NumPad 6) to move the object by one pixel.