[css-text-decor] Fixes to UA stylesheet rules for text-emphasis/underline-position per <https://www.w3.org/mid/CAMdq698pGQvDT+m2cX8w35CVmh-kxNNjRa8rcUzAMZ-a5i_Uwg@mail.gmail.com> and <https://www.w3.org/mid/5C756B1C-F03B-4CA7-8796-7A6EEBC34C32@apple.com>

Author: fantasai

css-text-decor/Overview.bs

@@ -938,18 +938,18 @@ Appendix B: Default UA Stylesheet</h2>
         rt { text-emphasis: none; }
 
         /* set language-appropriate default emphasis mark position */
-        :root:lang(zh), [lang|=zh] {
-          text-emphasis-position: under right;
-        }
-        :root:lang(ja), [lang|=ja], :root:lang(ko), [lang|=ko] {
-          text-underline-position: under right;
-        }
+        :root:lang(zh), [lang|=zh] { text-emphasis-position: under right; }
+        [lang|=ja]                 { text-emphasis-position: over right; }
 
         /* set language-appropriate default underline position */
-        :root:lang(zh), [lang|=zh] {
-          text-underline-position: under left;
+        :root:lang(ja), [lang|=ja],
+        :root:lang(ko), [lang|=ko] { text-underline-position: under right; }
+        :root:lang(zh), [lang|=zh],
+        :root:lang(mn), [lang|=mn] { text-underline-position: under left;  }
+        [lang]:not([lang|=zh], [lang|=ja], [lang|=ko], [lang|=mn]) {
+           text-underline-position: auto;
         }
-</code></pre>
+      </code></pre>
     </div>
 
     <p class="issue">
@@ -993,4 +993,5 @@ Changes</h2>
         (<a href="https://www.w3.org/mid/56E86D82.10606@inkedblade.net">Issue</a>)
     <li>Added note to indicate that initial behavior of 'text-decoration-skip' with respect to leading and trailing spaces may change.
     <li>Fixed “Computed value” line for 'text-shadow'.
+    <li>Various corrections to the default UA rules for 'text-emphasis-position' and 'text-underline-position'.
   </ul>