Use a fluid width with min and max width so that the reading span does not grow too big or small. No matter what screen you have, anything longer than 70-80 cha

Use a fluid width with min and max width so that the reading span does not grow too big or small. No matter what screen you have, anything longer than 70-80 chars in a single line is a pain to read. That is the reason readability and Safari Reader are designed the way they are. Use em/% to go screen size free.