Right side of colormap previews cut off

[mfisher87]

JupyterGIS version

v0.5.0

Description

Viridis is yellow on the right, but it only goes to green. Hot is white on the right, but it only goes to yellow.

The actual classification and rendering works OK though, it's just these little previews from the dropdown that are cut-off

[mfisher87]

See also #945 for more context :)

[nakul-py]

@mfisher87 We can also add ColorRamp name onto the Selected Ramp as we discuss earlier.