v3.6.1: Bugfixes including jQuery update to 3.7.1

This release contains changes associated with the following GitHub issues:

#271: Correct accessibility issue when <h1> text is an empty string.
#276: Correct misspelled CSS property name: cursor, not curser.
#278: Add titles for accessibility on Navigation Previous/Next buttons.
#279: "Fit" content on shipping-estimator form fields so that they're not 100% wide.
#280: Add spaces between text values on shopping-cart display page.
#281: Ensure that the quantity-update icon is an FA icon, regardless of the Update button's title's character length.
#284: Refactor shopping-cart page layout, especially for small screens.
#286: Correct shopping-cart delete icon/checkbox formatting when a product has a fixed-quantity display.
#288: Update jQuery to 3.7.1.
#289: Correct header/logo area layout.