[css-backgrounds-4] Add example for angle corner-shape, re-add definition of angle, reword issue

Author: LeaVerou

css-backgrounds-4/Overview.bs

@@ -269,23 +269,42 @@ Corner Shaping: the 'corner-shape' property</h3>
 		<dt><dfn>''round''</dfn>
 		<dd>Border radii define a convex elliptical curve at the corner.
 		<dt><dfn>''angle''</dfn>
+		<dd>Border radii define a diagonal slice at the corner.
 	</dl>
 
 	<div class="example">
 		For example, the following declarations create a right-pointing next button.
 		<pre>
 			a {
-				border-radius: 0 2em 2em 0;
-				corner-shape: angle;
-				padding: 0.5em 2em 0.5em 0.5em;
+				border-radius: .3em .8em .8em .3em / .3em 50% 50% .3em;
+				corner-shape: round angle angle round;
+				padding: .5em 1em .5em .5em;
+			}
 		</pre>
+		<div style='font: bold 200%/1 sans-serif;
+			width: 2.3em;
+			padding: .5em 1em .5em .5em;
+			border-radius: .3em 0 0 .3em;
+			background: url(&apos;data:image/svg+xml,\
+			<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 80 40">\
+			    <path d="m 0 0 h 65 l 10 20 l -10 20 h -65 z" fill="yellowgreen" />\
+			</svg>&apos;) no-repeat 0 / auto 100%'>
+			Next
+		</div>
 		As a fallback in UAs that don't support 'border-radius',
-		the right side would be rounded rather than pointy.
+		the right side would be rounded rather than pointy:
+		<div style='font: bold 200%/1 sans-serif;
+			width: 2.3em;
+			padding: .5em 1em .5em .5em; 
+			border-radius: .3em .8em .8em .3em / .3em 50% 50% .3em;
+			background: yellowgreen'>
+			Next
+		</div>
 	</div>
 
 	<p class="issue">
-		Add a ''cubic-bezier()'' function for random other shapes?
-		Or some other functions?
+		How to allow custom corners? Perhaps a ''path()'' function? Or a ''cubic-bezier()''?
+		Something else?
 
 <h3 id="corners-shorthand">
 Corner Shape and Size: the 'corners' shorthand</h3>