We took care to make it easy to read for elderly people and those with visual impairments, by enlarging the text and adding space between characters and lines.
Formal written register, typical of accessibility statements or style notes. The sentence chains multiple clauses with ~し (continuous form of します, linking parallel actions): 大きくし…もたせ…注意した. や is the non-exhaustive list marker 'and, or (and others)' — softer than と which is exhaustive. ~の方 'person who' is the polite way to refer to people in a category. ~ように 'so that' marks the purpose of the design decisions. Noun phrases like 文字間 and 行間 combine 字間 'between characters' etymologically.