Extra space at the bottom of the panel in sphinx-rtd-theme

reiyw commented 2 years ago

Describe the bug

When sphinx-rtd-theme is applied as a theme, a space appears at the bottom of the panel that should not be needed.

.. tabs::

   .. tab:: Apples

      Apples are green, or sometimes red.

.. tabs::

   .. code-tab:: c

         int main(const int argc, const char **argv) {
           return 0;
         }

will be rendered as:

The cause of this problem seems to be the way margins between content are spaced in sphinx-rtd-theme. Basically, sphinx-rtd-theme uses margin-bottom to control the space between contents. However, if one always leaves a bottom margin, they will end up with extra space at the bottom in so-called adomonition and other elements enclosed in boxes. To deal with this, sphinx-rtd-theme sets margin-bottom: 0 for the last child element contained in such elements.

https://github.com/readthedocs/sphinx_rtd_theme/blob/0da22b885be387b79f7552c92be00fd14d11228a/src/sass/_theme_rst.sass#L126-L133

However, this adjustment is not applied to classes introduced by sphinx-tabs, so the extra space remains.

The workaround is to set margin-bottom: 0 for the last child as in sphinx-rtd-theme.

.sphinx-tabs .sphinx-tabs-panel *:last-child {
    margin-bottom: 0;
}

But this is not a proper solution. In fact, if you apply this CSS to the default Sphinx theme (alabaster), you will strip off too much margin at the bottom.

I am a CSS newbie, so if you have a more general solution, that would be great.

Reproduce the bug

Install sphinx-rtd-theme:

$ pip install sphinx-rtd-theme==1.0.0

Edit your conf.py file's html_theme setting:

html_theme = "sphinx_rtd_theme"

Then just use the sphinx-tabs.

List your environment

pip freeze

```console $ pip freeze alabaster==0.7.12 Babel==2.10.3 build==0.8.0 certifi==2022.6.15 charset-normalizer==2.0.12 click==8.1.3 docutils==0.17.1 idna==3.3 imagesize==1.3.0 importlib-metadata==4.12.0 Jinja2==3.0.3 markdown-it-py==2.1.0 MarkupSafe==2.1.1 mdit-py-plugins==0.3.0 mdurl==0.1.1 myst-parser==0.18.0 packaging==21.3 pep517==0.12.0 pip-tools==6.7.0 Pygments==2.12.0 pyparsing==3.0.9 pytz==2022.1 PyYAML==6.0 requests==2.28.0 snowballstemmer==2.2.0 Sphinx==4.5.0 sphinx-rtd-theme==1.0.0 sphinx-tabs==3.4.0 sphinxcontrib-applehelp==1.0.2 sphinxcontrib-devhelp==1.0.2 sphinxcontrib-htmlhelp==2.0.0 sphinxcontrib-jsmath==1.0.1 sphinxcontrib-qthelp==1.0.3 sphinxcontrib-serializinghtml==1.1.5 tomli==2.0.1 typing_extensions==4.2.0 urllib3==1.26.9 zipp==3.8.0 ```

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reiyw commented 2 years ago

Oops, I overlooked https://github.com/executablebooks/sphinx-tabs/issues/139

executablebooks / sphinx-tabs