Accessibilty, first pass (#17)

* Placeholder color contrast @ WCAG 2.0 level AA

* Trailing whitespace removed.

* Remove redundant labels.

* Logo is a link in mobile, if not-embedded; otherwise, span. Fix link labels.

* HREF mandatory on A; menu behaves like a popup button.

* Hide icons from screen readers.

* About icon id keyboard-operarable and is labeled.

* Note about inaccessible modal.

* Missing closing tag.

* Fix nesting/indentation.

* Fix nesting/indentation; add missing closing tag.

* Trailing whitespace removed.

* Don't use NAV landmark for non-nav; add heading for page structure.

* Hide icon.

* Load archive form's buttons visibly receive keyboard focus.

* Trailing whitespace removed.

* "Hide" header button is keyboard-operable, and more-verbosely labeled for screenreader users.

* Don't use NAV landmark for non-nav; add heading for page structure.

* Sort order announced to screen reader users.

* Trailing whitespace removed.

* Delete button only a button when it can be pressed; announce in progress deletion.

* Trailing whitespace removed.

* Use a NAV landmark for replay controls.

* Remove "menu" role, to avoid having to implement arrow key support https://www.w3.org/WAI/GL/wiki/Using_ARIA_menus

* Hide icons.

* Label buttons.

* Links in disguise as buttons need HREF, and to respond to spacebar.

* Re-dub "main menu" to distinguish from replay menu

* Replay nav buttons visually get keyboard focus.

* Trailing whitespace removed.

* Hiding icons; button labels; links-as-buttons are operable.

* Use type=search for additional clarity.

* Add appropriate landmarks and a heading for structure and clarity.

* Tab selection is a nav, and is keyboard operable.

* Indentation; missing closing tag.

* Trailing whitespace removed.

* Title iframe.

* Not a navigation.

* Per discussion, rename tab to "URLs" (label only; route etc. the same while experimenting).

* Announce when expanded/collapsed.

* Remove "menu" to avoid having to implement expected keyboard support.

* Use correct heading level when in sidebar and when main.

* Trailing whitespace removed.

* Semantic markup of table; headings and captions; link-buttons are keyboard operable.

* Skip links for keyboard users.

* Title iframe; hide icon.

* Just a list, not an aside.

* Not an article.

* Remove trailing whitespace.

* Make each page in the list a heading.

* link-buttons are keyboard operable.

* Use semantic list for page list.

* Announce changes to search results.

* More wayfinding tweaks.

* Landmark and heading for replay.

* Dynamic page titles.

* Remove redundant labels from main landmarks.

* additional tweaks after rebase
- add 'role' to each of the tabs, dependent if sidebar or not
- add 'role=main' for replay
- add sr-only headers to each tab

* fix typos

* remaining tweaks:
- url-resources: fix sorter getting moved into notification
- url-resources: fix border for mobile view
- add screenreader labels to expand/hide buttons

* Show hover effect on focus.

* Wrap the whole sidebar is role=complementary, including the tab navigation.

* Make buttons keyboard operable; fix typos.

* Programmatically associate sidebar toggle button with sidebar.

* Per discusson, try calling this "URLs"

* Different heading levels for sidebar and main.

* Announce changes to search results.

* Correct dynamic page title, whe not in sidebar.

* Remove hyperlink focus decoration; reveal obscured focus indicator.

* Focus on replay, when replay changes.

* Make buttons keyboard operable.

* Move spacebar helper to misc instead of duplicating.

* Bump compiled assets.

* Use disabled attribute to match css; update label to describe new sidebar.

* Adjust replay focus styles.

* Adjust replay nav button focus, so visuals onclick in Chrome are less prominent.

* Put wordmark with logo on non-embed desktop, so that logo and wordmark make a single link.

Co-authored-by: Ilya Kreymer <ikreymer@gmail.com>

src/misc.js

@@ -18,6 +18,17 @@ function wrapCss(custom) {
 const IS_APP = window.IS_APP || window.electron && window.electron.IS_APP || window.matchMedia('(display-mode: standalone)').matches;
 
 
+// ===========================================================================
+// Buttons are expected to respond to both enter/return and spacebar.
+// If using `<a>` with `role='button'`, assign this handler to keyup.
+function clickOnSpacebarPress(event) {
+  if (event.key == " ") {
+    event.preventDefault();
+    event.target.click();
+  }
+}
+
+
 // ===========================================================================
 class FaIcon extends LitElement
 {
@@ -117,4 +128,4 @@ class AnimLogo extends FaIcon
 customElements.define("fa-icon",  FaIcon);
 customElements.define("wr-anim-logo", AnimLogo);
 
-export { wrapCss, IS_APP, rwpLogo, FaIcon, AnimLogo };
+export { wrapCss, IS_APP, clickOnSpacebarPress, rwpLogo, FaIcon, AnimLogo };