The cur­rent sur­face forms for dig­i­tal books are far from per­fect, but they work and are get­ting bet­ter with each device and soft­ware iter­a­tion. So, in my opin­ion, many of the crit­i­cal future ques­tions dig­i­tal books design­ers will have to address don’t directly involve pure con­tent lay­out. Future-book design is not merely about font sizes and lead­ing. Instead, our hard­est (and pos­si­bly most reward­ing) prob­lems will involve the inter­min­gling of con­tent and data.