Use vawy line instead of background decoration?

Vawy lines are the default way of highlighting errors in modern text editors. This extension however, uses the vim-like background styling (which is also nice), but might not be intuitive for some users; I find it a little bit distracting and would prefer the red vawy line instead.

I managed to get vawy lines by modifying the styles.css:

.CodeMirror .cm-spell-error:not(.cm-url):not(.cm-tag):not(.cm-word) {
     text-decoration-line: underline;
     text-decoration-style: wavy;
     text-decoration-color: red;
     /* For Chrome */
     text-decoration-skip-ink: none;
}

A more browser-independent version could use background images, but the above one is probably more light-weight and performant. Currently the text-decoration styling is supported for 75-89% of users globally (thouh the figure should be higher for people who work with Jupyter as I expect such users to be aware of risks of using outdated browsers).

If I open a PR, would you consider merging it, or are there reasons for keeping the current red background instead?

[StevenLi-DS]

I think it might be better to increase the alpha of the background color a bit since it is a little bit hard to see while using the dark theme in jupyter lab

[krassowski]

See: https://github.com/ijmbarr/jupyterlab_spellchecker/pull/45