You should be able to do something without much fuss using HTML 5 and
either Pyjamas (which compiles Python code to Javascript) or Brython
(a more or less complete implementation of Python within Javascript).
For example, see the clock demo on the Brython web page.
Pyjamas is the more established and probably more stable of the two
projects, but you should be aware that there are currently two active
forks of Pyjamas and some controversy surrounding the project
leadership.