[css-tables] Allow backgrounds of collapsed rows to be drawn under spanning cells which are still visible to avoid a different rendering of the cells; fix #478

Author: FremyCompany

css-tables-3/Overview.bs

@@ -2716,14 +2716,24 @@ With a table-internal box as non-containing block parent</h3>
 		As stated in CSS 2.2, if a <a>table-cell</a> has its visibility set to that of collapse, it is rendered the same as
 		if it had <a href="http://www.w3.org/TR/CSS22/visufx.html#visibility">visibility: hidden</a> set.
 
-		If the <a>table-cell</a> is spanning more than one <a>table-track</a>, and the <a>table-track</a> is set to 
+		<div class="note">
+
+			This happens when you set visibility:collapse on a table-row that contains a table-cell.
+			If you want to hide a row but continue to display its cells that span other rows, 
+			set visibility:visible on those cells to prevent them from inheriting their value.
+
+		</div>
+
+		If the <a>table-cell</a> is spanning more than one <a>table-track</a>, and at least one of those <a>table-track</a> is set to 
 		<a href="http://www.w3.org/TR/CSS22/visufx.html#visibility">visibility: collapse</a> then clip the content
-		to the <a>table-cell</a>'s border-box.
+		to the <a>table-cell</a>'s border-box. This means that the top left (top right in rtl) content of the cell will continue to show,
+		regardless of which of the tracks the cell spans has been collapsed.
 
 		<h4 id="visibility-collapse-track-rendering">Rendering a visibility: collapse table-track or table-track-group</h4>
 		When a <a>table-track</a> or <a>table-track-group</a> has <a href="http://www.w3.org/TR/CSS22/visufx.html#visibility">visibility: collapse</a>, 
-		none of backgrounds, borders or outlines that are contributed by the cells within the given <a>table-track</a> or 
-		<a>table-track-group</a> are painted.
+		all the backgrounds, borders or outlines that are contributed by the cells within the given <a>table-track</a> or 
+		<a>table-track-group</a> will continue to be painted on cells that have not been fully collapsed
+		(because they spanned multiple tracks).
 
 
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