Simplify flow-relative mapping, since we're not dealing with logical properties

Author: fantasai

css3-writing-modes/Overview.src.html

@@ -1814,38 +1814,33 @@ <h3 id="logical-direction-layout">
 Flow-Relative Mappings</h3>
 
   <p>Flow-relative directions are calculated with respect to
-    the writing mode of the element and used to abstract layout
-    related to padding and border properties. For example, if
-    an element had computed values of ''direction: ltr;
-    writing-mode: vertical-lr; text-orientation: vertical-right'',
-    'padding-top' would give its start padding, and 'padding-left'
-    would give its before padding.
-
-  <p>Flow-relative directions are calculated with respect to
-    the writing mode of the <em>parent</em> of the element
-    and used to abstract layout related to the margin properties
-    and the 'top', 'bottom', 'left', and 'right' properties.
-    (For the root element, which has no parent, the values of
-    the writing mode of the element is used instead.)
+    the writing mode of the <em>containing block</em> of the
+    element and used to abstract layout rules related to the
+    box properties (margins, borders, padding) and any properties
+    related to positioning the box within its containing block
+    ('float', 'clear', 'top', 'bottom', 'left', 'right')
+    For inline-level elements, the writing mode of the <em>parent
+    element</em> is used instead.
+
+  <p>For example, the margin that is dropped when a box's inline
+    dimension is
+    <a href="http://www.w3.org/TR/CSS21/visudet.html#blockwidth">over-constrained</a>
+    is the end margin as determined by the writing mode of the
+    containing block.
 
   <p>The <a href="http://www.w3.org/TR/CSS21/box.html#collapsing-margins">margin
     collapsing rules</a> apply exactly with the <em>before
     margin</em> substituted for the top margin and the
     <em>after margin</em> substituted for the bottom margin.
-    Similarly the padding and border on the same side as the
-    before margin is substituted for the top padding and
-    border, and the padding and border on the same side as
-    the after margin for the bottom padding and border.
+    Similarly the before padding and border are substituted
+    for the top padding and border, and the after padding and
+    border substituted for the bottom padding and border.
     Note this means only before and after margins ever collapse.
 
-  <p class="note">The parent element is used instead of the
-    containing block, because the benefit of using the containing
-    block is very rare, but the cost to implement it is rather
-    high for implementations that do abstract-physical mapping
-    at cascade time.</p>
+  <p>Flow-relative directions are calculated with respect to
+    the writing mode of the element and used to abstract layout
+    related to the element's contents:
 
-  <p>The start and end directions are also used for inline
-    layout as follows:
   <ul>
     <li>The initial value of the 'text-align' property
       aligns to the start edge of the line box.