zotero/scss/components/_exportOptions.scss

#zotero-export-options {
	#export-option-includeAnnotations {
		margin-top: 2px;
		margin-left: 17px;
	}
	
	checkbox[disabled=true] label {
		opacity: .5;
	}

	/* Override rules from Mozilla checkbox.css that make text almost unreadable when disabled
	   when combined with our opacity: .5 */
	checkbox[native][disabled="true"] {
		color: unset;
	}
}