Border and shade of tooltips gone

[agri]

Hi there,
after some upgrades an other "fiddling around", I lost border and shade of tooltips:

Does anyone know, where those are set (css, js, json ...)?
Regards

[agri]

Addendum:

The following applies to all themes:

EspoCRM 9.0.8
In e.g. client/css/espo/espo.css, you find the declaration for tooltip (popover) box border and shadow:

.autocomplete-suggestions, .dropdown-menu, .popover, .selectize-dropdown, .selectize-dropdown.form-control, .ui-timepicker-wrapper {
border: var(--dropdown-border-width) solid var(--dropdown-border);
box-shadow: var(--dropdown-box-shadow);
border-radius: var(--dropdown-border-radius);
border-width: var(--dropdown-border-width)
}


EspoCRM 9.1.1
In my case, in espo.css, the mentioned part is missing!