Learn French: C'est une édition dont la typographie n'est guère lisible. - It's an edition whose typography is hardly legible.

ne... guère means "hardly" or "barely." It is a two-part negation that completely replaces ne... pas, similar to how ne... jamais (never) works. You wrap it around the conjugated verb (est), which is why we get n'est guère.

Is ne... guère common in everyday spoken French?

Not really. It belongs to a more formal or literary register, which fits well with a sentence discussing book editions and typography. In casual conversation, a French speaker would more likely say n'est pas très lisible (isn't very legible) or est à peine lisible (is barely legible).

Why do we use dont here instead of que or qui?

In this sentence, dont translates to "whose" and shows possession. It links the edition to its typography (the typography of the edition). Note that in French, you still need the definite article la after dont, making the structure literally "whose the typography" (dont la typographie).

Where does lisible come from, and what is its opposite?