- `ax.axline`
[`ax.axline`](https://matplotlib.org/stable/api/_as_gen/matplotlib.axes.Axes.axline.html) can now be used for [matplotlib>=3.3.0](https://matplotlib.org/stable/users/prev_whats_new/whats_new_3.3.0.html#new-axes-axline-method) and mpltern. See [gallery](https://mpltern.readthedocs.io/en/latest/gallery/intermediate/axline.html).
- `tight_layout` and `constrained_layout`
Previously `tight_layout` and `constrained_layout` did not work as expected, which is fixed in mpltern 0.4.0.
- No overlaps between titles and ternary axes
As done in Matplotlib.
- Removal of `opposite_ticks`
Instead, `ax.taxis.set_ticks_position` and `ax.taxis.set_label_position` etc. should be used explicitly. See [gallery](https://mpltern.readthedocs.io/en/latest/gallery/axis_and_tick/tick_position.html).