clarified fonts;

--- a/etc/isabelle.css	Thu Mar 02 16:25:17 2017 +0100
+++ b/etc/isabelle.css	Thu Mar 02 16:46:22 2017 +0100
@@ -2,18 +2,18 @@
 
 @font-face {
   font-family: 'IsabelleText';
-  src: url('IsabelleText.ttf') format('truetype');
+  src: url('fonts/IsabelleText.ttf') format('truetype');
 }
 
 @font-face {
   font-family: 'IsabelleText';
-  src: url('IsabelleTextBold.ttf') format('truetype');
+  src: url('fonts/IsabelleTextBold.ttf') format('truetype');
   font-weight: bold;
 }
 
 @font-face {
   font-family: 'Vacuous';
-  src: url('Vacuous.ttf') format('truetype');
+  src: url('fonts/Vacuous.ttf') format('truetype');
 }
 
 body { background-color: #FFFFFF; }

--- a/src/Pure/Admin/news.scala	Thu Mar 02 16:25:17 2017 +0100
+++ b/src/Pure/Admin/news.scala	Thu Mar 02 16:46:22 2017 +0100
@@ -14,6 +14,8 @@
   def generate_html()
   {
     val target = Path.explode("~~/doc")
+    val target_fonts = target + Path.explode("fonts")
+    Isabelle_System.mkdirs(target_fonts)
 
     File.write(target + Path.explode("NEWS.html"),
       HTML.begin_document("NEWS") +
@@ -22,7 +24,9 @@
       "</pre>\n" +
       HTML.end_document)
 
-    for (font <- Isabelle_System.fonts()) File.copy(font, target)
+
+    for (font <- Isabelle_System.fonts(html = true))
+      File.copy(font, target_fonts)
 
     File.copy(Path.explode("~~/etc/isabelle.css"), target)
   }

--- a/src/Pure/Thy/present.scala	Thu Mar 02 16:25:17 2017 +0100
+++ b/src/Pure/Thy/present.scala	Thu Mar 02 16:46:22 2017 +0100
@@ -100,9 +100,10 @@
     name: String)
   {
     val session_prefix = browser_info + Path.basic(info.chapter) + Path.basic(name)
+    val session_fonts = session_prefix + Path.explode("fonts")
 
     if (info.options.bool("browser_info")) {
-      Isabelle_System.mkdirs(session_prefix)
+      Isabelle_System.mkdirs(session_fonts)
 
       val session_graph = session_prefix + Path.basic("session_graph.pdf")
       File.copy(graph_file, session_graph.file)
@@ -111,7 +112,7 @@
       File.copy(Path.explode("~~/etc/isabelle.css"), session_prefix)
 
       for (font <- Isabelle_System.fonts(html = true))
-        File.copy(font, session_prefix)
+        File.copy(font, session_fonts)
     }
   }
 }