The package provides an environment for coloured and framed
text boxes with a heading line. Optionally, such a box may be
split in an upper and a lower part; thus the package may be
used for the setting of LaTeX examples where one part of the
box displays the source code and the other part shows the
output. Another common use case is the setting of theorems. The
package supports saving and reuse of source code and text
parts.

Homepage:
https://ctan.org/pkg/tcolorbox
