Improve centering.
Improve centering.

foxxyz/json-schema-viewer,amitdesai03/json-schema-viewer,amitdesai03/json-schema-viewer,adiwg/mdTools,jlblcc/json-schema-viewer,foxxyz/json-schema-viewer,jlblcc/json-schema-viewer,adiwg/mdTools,jlblcc/json-schema-viewer