Technologies are described herein for providing an assistive graphical user interface for preserving document layout while improving readability, such as for persons with dyslexia or another type of reading disability. A document including one or more lines of text can be edited in first and second editing modes. When a request is received to edit the document in the second editing mode, the width of the lines when displayed using a non-assistive font is computed. The width of the lines when displayed using an assistive font, such as a font configured for use by persons with dyslexia, is also computed. A ratio between the width of the lines when displayed using the non-assistive font and the width of the lines when displayed using the assistive font is also computed. The width of the page is then expanded based upon the ratio and the lines are displayed using the assistive font.