Rephrasing section 6 title.

Author: Adenilson

css-round-display/Overview.bs

@@ -273,7 +273,7 @@ The example below shows how the 'border-boundary' property works on drawing bord
 <p class="note">Note: If the value of 'border-boundary' is parent or display, border lines of the element are actually just a visual effect. It triggers a layout for rendering in a general way, but in the above cases (border-boundary: parent|display), the layout doesn't occur and it only draws the border lines inward from the containing block's borders. With this situation, the borders might hide contents around the display edge.
 </p>
 
-<h2 id="positioning-content">Positioning content by using the polar coordinate system</h2>
+<h2 id="positioning-content">Content positioning using polar coordinate system</h2>
 
 <p>
 Polar coordinate system is a two-dimensional coordinate system that describes the position of a point in a plane with a distance from a reference point and an angle from a reference direction. Elements could be placed along a circle or concentric circles, and the polar coordinate system is useful to handle such cases.