This is an interesting solution: https://librarysearch.kent.ac.uk/client/en_GB/kent/search/results?ln=en_GB&ir=Both&q=art#topOfPage

Does somebody have examples of sites which do this well? Could you post URLs and maybe screenshots?

Change background of the exclude icon (thank you, FF):

.available-facets .section-content .md-chips .md-chip .md-button:before
{background-color: #fff; }

Example https://basel.swisscovery.org/discovery/search?query=any,contains,css&tab=UBS&search_scope=UBS&vid=41SLSP_UBS:live&lang=en

----

If somebody knows how to right align the icons, please let me know.

Change border colour of the include check box:

md-checkbox .md-icon {
border-color: #DDD !important ;
}

---

Change background colour of 'Apply Filters':

.multiselect-submit .multiselect-submit-inner .md-button.md-primary, .prm-positive-bg {
background-color: #008488;
}

.multiselect-submit:hover .multiselect-submit-inner:hover .md-button.md-primary:hover, .prm-positive-bg:hover {
background-color: #A5D7D2;
}
---

Change the colour of the exclude icon:

.available-facets .section-content .md-chips .md-chip .button-exclude {
color: #ECECEC;
}

---

Thank you, JC!

Thank you, Nancy!

Here's the css that our webmaster (University at Buffalo Libraries) suggests adding to the css file:

To display the facet select boxes persistently:

.multiselect-facet-group.multiselect-inactive .md-chip md-checkbox {
transform: scaleX(1);
}

To display the facet Exclude boxes persistently:

.section-content .md-chips .md-chip .md-chip-remove-container .md-button {
opacity: 1;
}

You can see it at https://suny-buf-psb.primo.exlibrisgroup.com/discovery/search?vid=01SUNY_BUF:ExLib_Default_for_Test

swisscollections.ch has an elegant solution

(Not Primo / Primo VE)

I see that Buffalo has made the first of the steps by making include static:
https://search.lib.buffalo.edu/discovery/search?query=any,contains,discovery&tab=LibraryCatalog&search_scope=MyInstitution&vid=01SUNY_BUF:catalog&offset=0
(Primo VE)

---
And as Anne mentioned, Washington shows both include and exclude (Primo)

https://alliance-primo.hosted.exlibrisgroup.com/primo-explore/search?search_scope=all&tab=default_tab&institution=01ALLIANCE_UW&vid=UW&displayMode=full&bulkSize=10&highlight=true&dum=true&pcAvailabiltyMode=true&query=any,contains,facets&displayField=all&queryTemp=facets

There's another problem with the UX as it is at the moment:
When you do an OR selection by putting a checkmark left to several facets at once, this only works correctly for facets within the same facet type.
If you combine facets from different types, the search that is done is AND, not OR.

We found out how poor the user experience was with facets when we did a three-part UX study in 2017 on the NUI. Users will not hover to include or exclude unless they graze the area of the facets by accident. We had so much of a problem with this that we had to build in our own code to keep everything static however, this code breaks every other release. Please build in this functionality.

"making the filter options static - including the persistent (lock) option- would go a long way to improving the usability of facets for users."

This is also true in Primo VE.

MS, that is the 'out of the box' default presentation of the filters, rather than a custom solution. It does clutter the interface less, but usability testing shows that it leads to most users never discovering that it's possible to filter by more than one filter in a facet group, or that it's possible to exclude filters. Therefore they are left with the impression that they can only filter by one resource type at a time, or one subject at a time, etc.

[Keren is right in her reply]

We have recently (January 2019) done some more usability testing on our instance of Primo and can confirm that students still can't even tell that a way to exclude facets exists, much less find out how to use it. We have only been using the new UI for 5 months, but even frequent users haven't stumbled across this functionality.

making the filter options static - including the persistent (lock) option- would go a long way to improving the usability of facets for users.
Too often we hear from students that they didn't know the system could do that. Static filter options (include, exclude, persistent) would enable users to see exactly what the system can do.