>>68
ChatGPTに聞いてみたら分かった

.bookmark-item:is([scheme="https"], [scheme="http"]) { image, > :is(.menu-icon, .menu-iconic-icon) {
content: url("chrome://browser/skin/places/folder-smart.svg") !important;
fill: #69c !important;
}
}
.bookmark-item[scheme="javascript"] { image, > :is(.menu-icon, .menu-iconic-icon) {
content: url("chrome://global/skin/dirListing/folder.png") !important;
}
}