Design on a grid.

Design on a grid.

Neatly aligned content is easier to read and looks better organized. Use a grid under your layout to provide it with an invisible support system. A grid which is the same from top to bottom and page to page provides a consistent and pleasant experience for the user.

Starting with a grid also makes it much easier to adapt the layout to additional screen sizes with responsive design.

Further Study

All About Grid Systems by Rachel Shillcock