Prevent font flashing in the docs (#23622)

... by moving the Google font includes near the top of the head. By
including them as early as possible, they are known, when the browser
starts rendering the body.

Test it by making the change manually in `doc/html/system.html` and then
press ctrl+f5 (reload without cache). This removes the font flashing.

Tested in Chrome and Firefox.

1 files changed, 4 insertions, 3 deletions

diff --git a/config/nimdoc.cfg b/config/nimdoc.cfg
index 5b902b362..99751f79d 100644
--- a/config/nimdoc.cfg
+++ b/config/nimdoc.cfg
@@ -232,6 +232,10 @@ doc.file = """<?xml version="1.0" encoding="utf-8" ?>
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <title>$title</title>
 
+<!-- Google fonts -->
+<link href='https://fonts.googleapis.com/css?family=Lato:400,600,900' rel='stylesheet' type='text/css'/>
+<link href='https://fonts.googleapis.com/css?family=Source+Code+Pro:400,500,600' rel='stylesheet' type='text/css'/>
+
 <!-- Favicon -->
 <link rel="shortcut icon" href="data:image/x-icon;base64,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"/>
 <link rel="icon" type="image/png" sizes="32x32" href="data:image/png;base64,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">
@@ -255,9 +259,6 @@ doc.file = """<?xml version="1.0" encoding="utf-8" ?>
     </div>
   </div>
   $analytics
-  <!-- Google fonts -->
-  <link href='https://fonts.googleapis.com/css?family=Lato:400,600,900' rel='stylesheet' type='text/css'/>
-  <link href='https://fonts.googleapis.com/css?family=Source+Code+Pro:400,500,600' rel='stylesheet' type='text/css'/>
 </body>
 </html>
 """