fix: remove up to the fence indentation from each content line

src/Tokenizer.ts

@@ -68,11 +68,9 @@ function indentCodeCompensation(raw: string, text: string, rules: Rules) {
 
       const [indentInNode] = matchIndentInNode;
 
-      if (indentInNode.length >= indentToCode.length) {
-        return node.slice(indentToCode.length);
-      }
-
-      return node;
+      // Up to the fence's own indentation is removed from each line, so a line
+      // indented less than the fence loses whatever indentation it has.
+      return node.slice(Math.min(indentInNode.length, indentToCode.length));
     })
     .join('\n');
 }

test/specs/new/fence_indent_stripping.html

@@ -0,0 +1,7 @@
+<pre><code>aaa
+ aaa
+aaa
+</code></pre>
+<p>sep</p>
+<pre><code>    aaa
+</code></pre>

test/specs/new/fence_indent_stripping.md

@@ -0,0 +1,14 @@
+---
+renderExact: true
+---
+   ```
+   aaa
+    aaa
+  aaa
+   ```
+
+sep
+
+  ```
+      aaa
+  ```