Fix a type `in line` -> `inline` in basic css challenge

Editor assessment

The subject shows its work: a typo in a basic css challenge was corrected from in line to inline, with the exact strings quoted, which is maximally clear without opening the diff. The capitalized start is a permitted style, and the fix type and curriculum scope are accurate. No body is present and none is needed; the subject is self-sufficient for a one-word correction. The PR reference is well formed. Minor blemishes: a type is written where typo is meant, an ironic slip, and the subject runs slightly long. Clear, honest, and complete for its size, making this a good, publishable small-fix example.