Improve default osm dark mode

[Nekzuris]

The tooltip is white in dark mode, see openstreetmap/openstreetmap-website#5329 (comment)
I should PR a fix directly to openstreetmap-website but idk how to integrate it properly with their .scss and test it.

[Nekzuris]

I also made a more modern search bar without the rectangular background and transparency like this:

my css, works on default but needs integration with your resizable sidebar:

#sidebar, .bg-body-secondary {
    background: none !important;
}    
#sidebar > div:not(:first-child) {
    background-color: rgba(var(--bs-body-bg-rgb), var(--bs-bg-opacity)) !important;
}
.search_form .form-control {
    background-color: rgba(255,255,255,.75);
}
@media(prefers-color-scheme: dark) {
    .search_form .form-control {
        background-color: rgba(0,0,0,.75) !important;
    }
}

[deevroman]

The tooltip is white in dark mode

in general, this is not critical, since users of the extension most likely do not read these tooltips :) But I'll think about it

modern search bar

I'll make a note for #89