nextcloud-server/core/css/public.scss

#body-public {
	.header-right {

		span:not(.popovermenu) a {
			color: $color-primary-text;
		}

		.menutoggle,
		#header-primary-action[class^='icon-'] {
			padding: 14px;
			padding-right: 40px;
			background-position: right 15px center;
			color: $color-primary-text;
			cursor: pointer;
		}

		#header-secondary-action {
			margin-right: 13px;
		}

	}
}