/series/{id}: adjust the sizes of the price/currency fields

[php-coder]

At this moment, the currency field is always smaller than the price field:

It is reproducible on Firefox/Safari on macOS.

Related code:

mystamps/src/main/webapp/WEB-INF/views/series/info.html

Lines 436 to 459 in a455950

	<p th:with="price_msg=#{t_price},paidUser=${#authorization.expression('hasAuthority(''ADD_SERIES_PRICE'')')}"
	th:attrappend="title=${paidUser ? null : '__#{t_only_for_paid_users}__'}">
	<span th:text="#{t_i_bought_for}" th:remove="tag">I bought for</span>
	<input id="paid-price"
	type="text"
	size="5"
	placeholder="price"
	th:placeholder="${#strings.unCapitalize(price_msg)}"
	th:field="*{price}"
	th:disabled="${paidUser ? null : 'disabled'}"
	/>
	<select id="paid-currency"
	th:field="*{currency}"
	th:disabled="${paidUser ? null : 'disabled'}">
	<option value=""></option>
	<option value="USD">USD</option>
	<option value="EUR">EUR</option>
	<option value="RUB">RUB</option>
	<option value="CZK">CZK</option>
	<option value="BYN">BYN</option>
	<option value="UAH">UAH</option>
	</select>
	</p>