Specify CSS file encoding

Fixes #21
diff --git a/static/css/pygments.css b/static/css/pygments.css
index d2e6e60..e7b1ca4 100644
--- a/static/css/pygments.css
+++ b/static/css/pygments.css
@@ -1,3 +1,5 @@
+@charset "UTF-8";
+
 /* See available classes at https://bitbucket.org/birkenfeld/pygments-main/src/default/pygments/token.py */
 
 .hll { background-color: #ffd800; padding-right:100%; }
diff --git a/static/css/style.less b/static/css/style.less
index 32bb0bb..8d8668c 100644
--- a/static/css/style.less
+++ b/static/css/style.less
@@ -1,3 +1,5 @@
+@charset "UTF-8";
+
 @black: #000000;
 @white: #ffffff;
 @light-grey: #eeeeee;