I guess I could use attribute selector but that doesn't seem right either:

.multiselect[group-values],
.multiselect[group-label],
.multiselect[group-select] {
    //My custom CSS
}

EDIT: Nvm, these attr shouldn't even be rendered in the DOM in the first place, I created a wrapper component and forgot to set inheritAttrs: false;

I've added the class in my wrapper component using the code bellow.
I still think this could be improved.

:class="{ 'has-option-group': $attrs['group-values'] || $attrs['group-label'] || $attrs['group-select'] }"

I've indented the options though this styling rule:

.multiselect__option:not(.multiselect__option--group) {
  padding-left: 20px;
}

To ensure that only the selectors with groups would be indented, I've also added a class called has-option-groups on the vue-multiselect element, and changed the rule to:

.has-option-groups .multiselect__option:not(.multiselect__option--group) {
  padding-left: 20px;
}

@shentao Can I open a PR for this or is there a reason why the option inside an optiongroup wouldn't be indented ?

Adding the indentation (as much as I like it) would impact existing styling. I would personally recommend the solution suggested above with a custom CSS rule.

If it could be added as an optional change then I think it’s okay. But I would refer to @mattelen @akki-jat if they would like to merge that.

@shentao Thanks for your reply. Any change will have impact, it might need to be release in a minor/major instead of a patch release as to not affect existing user.

The main problem with the custom CSS is for other library using depending on vue-multiselect. For exemple, I use outl1ne/nova-multiselect-field so it make it harder to override the styles.

I could contribute a PR to that package or override the style in all my Laravel Nova project, but the best would be to fix it in Vue-multiselect

@mrleblanc101 I would suggest adding proper classes so if anyone wants to overwrite the styles for the group parent and the children can do that and default styles will be the same as those are now

If you're ok with that I can open a PR, although I strongly feel that vue-multiselect should adopt indentation to match the HTML Select

@mrleblanc101 We can decide the one default style right, in the end we need to provide the capability to change it as the user wants. So for now we can keep it as it is but yes in the next major version we can try to make an indented style default one as I think it is better UX.

Do you want me to open 2 PR.
One for the class and one for the default indented style ?

@mrleblanc101 I think create one PR for the new class, and for the new default but the PR for the new default might take some time to merge in, as this would be something we can look at changing in V4.

In the meantime we want to release another update of V2, and get the Vue 3 compatible version of V3 published as stable.

TIA