fix(themes): improve contrast for code blocks and callouts in light theme

frontend/src/index.css

@@ -429,11 +429,11 @@ body {
     --code-keyword: #0000ff;
     --code-string: #a31515;
     --code-number: #098658;
-    --code-comment: #008000;
+    --code-comment: #007000;
     --code-property: #0451a5;
     --code-function: #795e26;
     --code-type: #267f99;
-    --code-punctuation: #3b3b3b;
+    --code-punctuation: #2e2e2e;
     --code-variable: #001080;
   }