zotero/chrome/content/zotero-platform/unix/overlay.css

/*
 Override selected, unfocused tree row highlight color, which is too similar to the alternating
 row color by default
*/
#zotero-collections-tree treechildren::-moz-tree-row(selected),
#zotero-items-tree treechildren::-moz-tree-row(selected) {
	background-color: #D4D4D4;
}

#zotero-collections-tree treechildren::-moz-tree-row(selected, focus),
#zotero-items-tree treechildren::-moz-tree-row(selected, focus) {
	background-color: Highlight;
}

#zotero-collections-tree treechildren::-moz-tree-row {
	height: 1.3em;
}


@media (min-resolution: 1.25dppx) {
	#zotero-pane .toolbarbutton-icon {
		width: 16px;
	}
	
	#zotero-tb-sync > .toolbarbutton-icon {
		width: 20px;
	}
}

/* Dropmarker added automatically on Linux */
.toolbarbutton-menu-dropmarker, #zotero-tb-search-menu-button {
	list-style-image: none;
}

.zotero-tb-button:not([type=menu]) {
	margin-right: 4px;
}

#zotero-tb-search-menu-button {
	-moz-appearance: toolbarbutton-dropdown !important;
	width: 12px;
	height: 12px;
}

#zotero-tb-search-menu-button .button-menu-dropmarker {
	display: none;
}

#zotero-tb-search .textbox-search-icon {
	visibility: hidden;
}

/* Fixes tabs missing styling on (GTK 3.20) Ubuntu 16.10. See https://bugzilla.mozilla.org/show_bug.cgi?id=1306425 */
tabpanels {
	-moz-appearance: none;
	border: 1px solid hsla(0, 0%, 0%, 0.2);
	
}
tab {
	-moz-appearance: none;
	border-top: 1px solid hsla(0, 0%, 0%, 0.2);
	border-right: 1px solid hsla(0, 0%, 0%, 0.2);
	border-left: 1px solid hsla(0, 0%, 0%, 0.2);
}
/* Fixes misc Ubuntu 16.10 rendering issue fixes. */
#zotero-prefs menulist dropmarker{
	width: 30px;
}
#zotero-prefs .numberbox-input-box{
	-moz-appearance: textfield;
}

#zotero-pane splitter {
	border: 0;
	width: 6px;
	background-color: transparent;
	background-image: none;
}

#zotero-context-splitter-stacked {
	-moz-appearance: none;
	background-color: #ececec;
	border-top: 1px solid hsla(0, 0%, 0%, 0.2);
}