zotero/scss/components/_search.scss

.search {
	position: relative;
	min-width: 40px;
	height: 36px;

	input {
		background: var(--material-background);
		border-radius: 5px;
		border: var(--material-border-quinary);
		color: var(--fill-primary);
		flex: 1 0;
		margin: 6px 0px;
		min-width: 40px;
		padding: 3px 7px;
	
		&::placeholder {
			color: var(--fill-tertiary);
			opacity: 1.0;
		}
	
		&:focus {
			outline: none;
			border-color: var(--color-focus-search);
			box-shadow: 0 0 0 calc(var(--width-focus-border) - 1px) var(--color-focus-search);
		}
	}

	.search-cancel-button {
		position: absolute;
		inset-inline-end: 0;
		width: 14px;
		height: 14px;
		padding-inline: 5px 8px;
		padding-block: 5px;
		margin-inline: 0 4px;
		margin-block: 6px;
		cursor: default;
		background: url(resource://gre-resources/searchfield-cancel.svg) no-repeat center/contain;
		background-size: unset;
	}
}

search-textbox {
	appearance: none;
	background: var(--material-background);
	border-radius: 5px;
	border: var(--material-border-quinary);
	color: var(--fill-primary);
	padding: 0;
	padding-inline-end: 6px;

	&::placeholder {
		color: var(--fill-tertiary);
		opacity: 1.0;
	}

	&:focus {
		outline: none;
		border-color: transparent;
		box-shadow: 0 0 0 var(--width-focus-border) var(--color-focus-search);
	}
}

:is(search-textbox)::part(search-sign),
:is(search-textbox)::part(search-icon) {
	@include svgicon-menu("magnifier", "universal", "16");
	color: var(--fill-secondary);
	// right: 2px padding + 8px dropmarker width + 4px padding + 6px padding
	// Use explicit left/right padding here because this element is flipped in RTL (see below)
	padding: 6px 4px 6px 6px;
	margin: 0;
}

:is(search-textbox):-moz-locale-dir(rtl)::part(search-sign),
:is(search-textbox):-moz-locale-dir(rtl)::part(search-icon) {
	transform: scaleX(-1);
}