thank you for providing the starting point!
I did not know, so other might also find this helpful:
the provided code snippet should be copied to custom.css, which can be edited from Settings → General → “Edit custom.css”
I wanted the “visible on hover / while editing” functionality. After some tinkering, I came up with:
:root:not(.is-native-android) .ls-block[haschild="false"][level="1"]:not([data-refs-self="@"]) > div > div > a > .bullet-container {
opacity: 0;
visibility: hidden;
pointer-events: none;
transition: opacity 120ms ease;
}
:root:not(.is-native-android) .ls-block[haschild="false"][level="1"]:not([data-refs-self="@"]):is(:hover, :focus-within) > div > div > a > .bullet-container {
opacity: 1;
visibility: visible;
pointer-events: auto;
}