Drop the shadow graphic under page content

.entrytext carried the theme's bottom.png as a centre-bottom background,
which rendered as a grey smudge trailing the last line of every page.
Removed the rule and the now-unused asset.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/styles/global.css

@@ -1132,7 +1132,6 @@ h2.post-title-color {
 
 
 .entrytext {
-	background: url("/theme-images/bottom.png") no-repeat scroll center bottom transparent;
     padding: 10px 0;
 }