The ornamental design for a shadowbox with a sport themed component, as shown and described.
FIG. 1 is a perspective front view of a shadowbox with a sport themed component;
FIG. 2 is a front elevation view of the shadowbox with a sport themed component;
FIG. 3 is a rear elevation view of the shadowbox with a sport themed component;
FIG. 4 is a left side elevation view of the shadowbox with a sport themed component; the right side elevation view being a mirror image thereof;
FIG. 5 is a top plan view of the shadowbox with a sport themed component; and,
FIG. 6 is a bottom plan view of the shadowbox with a sport themed component.
The shadow box is shown with a symbolic break in its depth, represented by broken lines. The appearance of any portion of the article between the broken lines forms no part of the claimed design.