。
I don't like baseball at all.
Literal
Baseball [topic-は] at-all likable [copula negation-ではない].
ちっとも~ない ('not at all, not in the slightest') is another negative-polarity intensifier (like 全然~ない and まったく~ない). Somewhat old-fashioned and conversational. 好きだ as na-adjective in the negative: 好きではない. Strong denial.