Accessibility added, v2.6.0d6 (S.T. 2.5.10).

= Reference container semantics for assistive technology =
- Table header elements with row scope in the first column.
- Table caption invisible to sighted users but required for screen readers.
= Referrer accessibility =
- jQuery referrers are accessible but don’t show the tooltips on focus.
- AMP compatible tooltips show up on focus on navigatable referrers.
- Alternative tooltips now accessible on focus on now navigatable referrers.

git-svn-id: https://plugins.svn.wordpress.org/footnotes/trunk@2498648 b8457f37-d9ea-0310-8a92-e5e31aec5664

css/dev-common.css

@@ -7,7 +7,7 @@
  * Since: 1.0
  * 
  * @version 2.6.0
- * @lastmodified 2021-03-16T1529+0100
+ * @lastmodified 2021-03-18T0448+0100
  *
  *     Classes recommended for Custom CSS:
  *     @see templates/dashboard/customize-css-new.html
@@ -66,7 +66,7 @@
  * @since 2.3.0  offset anchors for optional hard links, thanks to @psychonevro @martinneumannat bug reports
  * @since 2.4.0  validation error warning box
  * @since 2.5.0  validation error warning box more paragraphs
- * @since 2.5.11 AMP compatible tooltips and reference container
+ * @since 2.6.0  AMP compatible tooltips and reference container
  */
 
 /**
@@ -157,7 +157,7 @@
 /**
  * Optional hard links: anchors with scroll offset
  *
- * - Adding: Referrers and backlinks: optional hard links for AMP compatibility, thanks to @psykonevro bug report, thanks to @martinneumannat code contribution.
+ * - Adding: Referrers and backlinks: optional hard links for AMP compatibility, thanks to @psykonevro issue report, thanks to @martinneumannat issue report and code contribution.
  *
  * @since 2.3.0
  * @contributor @martinneumannat
@@ -356,6 +356,19 @@ table
 	border: none;
 }
 
+/*
+caption
+*/
+
+caption.accessibility {
+	text-align: start;
+	height: 1px;
+	width: 1px;
+	white-space: nowrap;
+	overflow: hidden;
+	color: #ffffff00;
+}
+
 /**
  * Footnotes list.
  *