zotero/scss/elements/_quickSearchTextbox.scss

quick-search-textbox {
	font-size: var(--zotero-font-size);
	margin-right: 0;
	width: 172px;
	height: 25px;
}

*[zoteroFontSize=small] quick-search-textbox {
	font-size: 11px;
}

#zotero-tb-search-menu-button {
	margin: 0;
	padding: 0;
	-moz-appearance: none;
	min-width: 0;
	cursor: default;
	list-style-image: url("chrome://zotero/skin/searchbar-dropmarker.png");
}

#zotero-tb-search-menu-button .button-icon {
	width: 7px;
}

#zotero-tb-search-menu-button .button-menu-dropmarker {
	display: none; /* Hide automatic dropmarker */
}

/* BEGIN 2X BLOCK -- DO NOT EDIT MANUALLY -- USE 2XIZE */
@media (min-resolution: 1.25dppx) {
	#zotero-tb-search-menu-button  { list-style-image: url("chrome://zotero/skin/searchbar-dropmarker@2x.png"); }
}