paper: apply styles from annotate tooltip to followlines popup

These new colors and styles are already used in the tooltip that gets shown
when user hovers over line numbers on annotate page. The old styles, replaced
in this patch, look completely unrelated to paper or any other hgweb theme.

mercurial/templates/static/style-paper.css

@@ -295,10 +295,9 b' pre.sourcelines > span.followlines-selec'
 }
 
 div#followlines {
-  background-color: #B7B7B7;
-  border: 1px solid #CCC;
-  border-radius: 5px;
-  padding: 4px;
+  background-color: #FFF;
+  border: 1px solid #999;
+  padding: 5px;
   position: fixed;
 }