rendered_markdown: Correct presentation of nested lists.

To properly increment counters, and display lists of the
correct type when nested, we need to use child selectors
and not the previous, overly generic descendant selectors.

web/styles/rendered_markdown.css

@@ -39,14 +39,14 @@
             }
         }
 
-        li {
+        & > li {
             /* This aligns bullets to roughly the
                center of a single-digit counter.
                11.2px at 16px/1em */
             padding-inline-start: 0.7em;
         }
 
-        & li::marker {
+        & > li::marker {
             /* This is an eyeballed value, but it makes the
                otherwise diminutive markers specified above
                both larger *and* better vertically centered. */
@@ -71,13 +71,13 @@
            same here to offset the counters. */
         padding-inline-start: 2.1ch;
 
-        & li {
+        & > li {
             counter-increment: count 1;
             /* 3.2px at 16px/1em */
             padding-inline-start: 0.2em;
         }
 
-        & li::marker {
+        & > li::marker {
             content: counter(count, decimal) ". ";
         }
     }