remove the css line (not used here)

Author: jasdumas

_pkgdown.yml

@@ -12,7 +12,6 @@ template:
   light-switch: true
   bootswatch: cosmo  # (Optional) Choose a theme
   includes:
-    in_header: extra.css
     before_body: |
       <style>
        .navbar {background: linear-gradient(-45deg, #F9B397, #D68A93, #AD92B1, #B07891); background-size: 200% 100%; animation: gradient 15s ease infinite;}