zotero/scss/components/_window.scss

@mixin zotero-window {
	background: var(--material-sidepane);
	--color-form-element-base-background: var(--material-sidepane);
}

@mixin zotero-dialog {
	background: var(--material-background);
	--color-form-element-base-background: var(--material-background);
}

window:root,
window:root > wizard,
body {
	@include zotero-window();
}

window:root > dialog {
	@include zotero-dialog();
}

// Can overwrite default style
window:root .zotero-window {
	@include zotero-window();
}

window:root .zotero-dialog {
	@include zotero-dialog();
}