The ornamental design for a containerbottom, as shown and described.
FIG. 1 is a view from the side of a container bottom showing my new design,
with the broken line showing, for illustrative purposes only, the
remainder of a container with which my new container bottom design may be
used and forming no part of the claimed design;
FIG. 2 is a view from below the container bottom of FIG. 1 showing my new
design; and,
FIG. 3 is a perspective view from below of the container bottom of FIGS. 1
and 2 showing my new design, with the broken line showing, for
illustrative purposes only, the remainder of a container with which my new
container design may be used and forming no part of my claimed design.