Can we disable theme presets switcher?

[roughnecks]

Hello,

I would like my site to only have 1 theme and it shouldn't be changed, so maybe add a way to disable the theme switcher?
Side-problem: when using a custom css, that applies to both dark and light presets, so that's obviously an issue, e.g.

.widget-type-bookmarks a {
    color: antiquewhite;
}

[netadptr0719]

I put the following in my custom CSS, it works, but an official way would be nice

.theme-picker {
        display: none
}

[roughnecks]

Ooh, I didn't think about this possibility and have already fixed my custom CSS to have a decent white theme too, but this is even better. Thanks!