Overflow columns can effect the multicol container height. Fixes #1745

Author: rachelandrew

css-multicol-1/Overview.bs

@@ -1119,7 +1119,7 @@ Pagination and overflow outside multicol containers</h3>
 	</ul>
 
 	Columns that appear outside the multicol container in continuous media
-	are called <dfn>overflow columns</dfn>.
+	are called <dfn>overflow columns</dfn>. Overflow columns can effect the height of the multicol container.
 
 	<div class="example">
 		In this example, the height of the multi-column container has been
@@ -1142,6 +1142,17 @@ Pagination and overflow outside multicol containers</h3>
 
 	</div>
 
+	<div class="example">
+		
+		In continuous media overflow columns can effect the height of the multicol container. In this example a column appears in the overflow which has four lines of text. The multicol container is made tall enough to accomodate this column.
+
+		<figure>
+			<img src="images/overflow-column-effects-height.svg" alt="Four columns, overflow column is taller than the first three">
+			<figcaption>The final column is an overflow column yet is taller than the others. The container is tall enough for this column.</figcaption>
+		</figure>
+
+	</div>
+
 	<div class="example">
 		In paged media, the overflow content goes into column on subsequent pages.
 		Given the same content as in the previous example
@@ -1200,12 +1211,15 @@ Pagination and overflow outside multicol containers</h3>
 		Due to column balancing, the last paragraph is split across three columns.
 	</div>
 
+
+
 <h2 class="no-num" id="changes">Appendix B. Changes</h2>
 
 This appendix is <em>informative</em>.
 
 <h3 id="changes-from-20171005">Changes from the <a href="https://www.w3.org/TR/2017/WD-css-multicol-1-20171005/">Working Draft (WD) of 5 October 2017</a></h3>
 <ul>
+    <li>Add a line of text plus an example to show that overflow columns can effect the multicol container height. <a href="https://github.com/w3c/csswg-drafts/issues/1745">Resolved: 12 Apr 2018</a></li>
 	<li>Replaced the HTML mock-up examples with SVG versions, as the examples were unclear. <a href="https://github.com/w3c/csswg-drafts/issues/1087">Issue 1087</a>.</li>
 	<li>Changed the value of normal for column-gap to be 1em, rather than a UA-specified length with a suggestion of 1em. <a href="https://github.com/w3c/csswg-drafts/issues/2145#issuecomment-378781507">Resolved: 4 Apr 2018</a></li>
 	<li>Clarified that negative values are not allowed for column-width, and that while 0 may be specified, used values will be clamped to a minimum of 1px. <a href="https://github.com/w3c/csswg-drafts/issues/1741#issuecomment-373091628">Resolved: 14 Mar 2018</a></li>