Citations not spanning whole doc area with sphinx-rtd-theme version 1.3.0

[saurabheights]

Problem

Citations layout is incorrect and works differently with or without new lines.

Reproducible Project

See below rst code. The first three citation are from https://github.com/readthedocs/sphinx_rtd_theme/blob/master/docs/demo/demo.rst#citations, rest are taken from Open3d which is built using v0.4.3 of sphinx_rtd_theme. I am upgrading their tech stack, but noticed references dont work when upgrading sphinx_rtd_theme. I have taken 3 of the references and added them, with and without new lines.

Citations
---------

.. [Citation] This is the citation I made, let's make this extremely long so that we can tell that it doesn't follow the normal responsive table stuff.

.. [12] This citation has some ``code blocks`` in it, maybe some **bold** and
       *italics* too. Heck, lets put a link to a meta citation [13]_ too.

.. [13] This citation will have two backlinks.

.. [ArujoAndOliveira2020] A. Arajo and M. Oliveira,
   A robust statistics approach for plane detection in unorganized point clouds, Pattern Recognition, 2020

.. [ArujoAndOliveira2020] A. Arajo and M. Oliveira, A robust statistics approach for plane detection in unorganized point clouds, Pattern Recognition, 2020

.. [Bernardini1999] F. Bernardini and J. Mittleman and HRushmeier and C. Silva and G. Taubin
   The ball-pivoting algorithm for surface reconstruction, IEEE transactions on visualization and computer graphics, 5(4), 349-359, 1999

.. [Bernardini1999] F. Bernardini and J. Mittleman and HRushmeier and C. Silva and G. Taubin, The ball-pivoting algorithm for surface reconstruction, IEEE transactions on visualization and computer graphics, 5(4), 349-359,
   1999

.. [ChenAndMedioni1992] Y. Chen and G. G. Medioni,
   Object modelling by registration of multiple range images, Image and Vision Computing, 10(3), 1992.

.. [ChenAndMedioni1992] Y. Chen and G. G. Medioni, Object modelling by registration of multiple range images, Image and Vision Computing, 10(3), 1992.

Notice that in case of Bernardini1999, adding a new line just before 1999 makes the citation layout work.

Error Logs/Results

Both error and expected results are below.

Environment Info

• Python Version: 3.8
• Sphinx Version: 7.1.2
• RTD Theme Version: 1.3.0

Setup done in fresh conda environment

conda create --name docs python=3.8 -y
conda activate docs
pip install sphinx-rtd-theme==1.3.0
sphinx-build -b html . _out

[saurabheights]

Copy pasting citation, I ended up using citation with same label, i.e. ChenAndMedioni1992 is used twice. However making them unique doesnt help.

Also, notice how the css is different for last two citations.

[humitos]

@saurabheights can you reproduce this issue with the latest release candidate 2.1.0rc1?