I am testing my upgrade to Accordions 2.1.18 under WP 5.3.2 and Tempera theme.
Following tests use Firefox as browser.
The styling looks OK for the accordion, as here
When displaying the same accordion as a tab, I cannot get the active text to display as black (rather than white), as here
There is an additional problem when displaying under IE.
Again the accordion is OK but, when displaying as a tab, the inactive header is a pale colour (not #bcd2ee as expected).