Improved search input for mobile

- font size 16px to prevent zooming on iOS Safari
- search input is scrolled into view on iOS Safari
- box-shadow is displayed correctly

assets/js/just-the-docs.js

@@ -133,7 +133,9 @@ function searchLoaded(index, docs) {
       hideSearch();
     } else {
       showSearch();
-      window.scroll(0, window.scrollY + mainHeader.getBoundingClientRect().top);
+      // scroll search input into view, workaround for iOS Safari
+      window.scroll(0, -1);
+      setTimeout(function(){ window.scroll(0, 0); }, 0);
     }
     if (input === currentInput) {
       return;