Add more accessible font to prevent autozoom on iOs (ParkingReformNet…

…work#181)

See: ParkingReformNetwork#177

IOs on mobile autozooms for fonts in input elements < 16px for
accessibility reasons.

This issue does not show up in devtools, use https://ngrok.com/ to try
this out on your mobile phone.

If you don't have an iphone please test with your android or other
smartphone (if you have one) as this would be useful data as well.

src/css/_header.scss

@@ -71,6 +71,15 @@ header {
   height: 40px;
 }
 
+.choices__input {
+  /*
+   * This is necessary to prevent autozoom on iOS 
+   * for accessibility reasons.  See:
+   * https://weblog.west-wind.com/posts/2023/Apr/17/Preventing-iOS-Safari-Textbox-Zooming
+   */
+  font-size: 16px;
+}
+
 .choices__list--dropdown,
 .choices__list[aria-expanded] {
   z-index: 1001;