get sphinx_rtd_theme's code-block to format properly

install: 

  - pip install --user sphinx  # sphinx_rtd_theme

  - sudo python -m pip install https://github.com/rtfd/sphinx_rtd_theme/archive/master.zip -U

    # pypi's sphinx_rtd_theme is outdated. Internet recommends using current

    # master. Note: at some point, it will be OK to add `sphinx_rtd_theme` to

    # the `pip install` above => remove line below:

  - python -m pip install --user https://github.com/rtfd/sphinx_rtd_theme/archive/master.zip -U

script: bash ./build_and_deploy.sh

    overflow: visible;

}

/* rtd_theme currently colours code-blocks in the pygments style (ie. green).

 * This overrides this design choice with white. Note: future versions of the

 * sphinx_rtd_theme might not need this HACK. */

.highlight {

    background: #ffffff;

}