fix compile on windows (with code page 1251)

diff --git a/css/postprocess.py b/css/postprocess.py
index 491f67579eefc1d5ada243c4ce6c098f12c86c59..4017f34ec4d3e6d1f1b11fa9c022e626ef8fb88d 100755 (executable)
--- a/css/postprocess.py
+++ b/css/postprocess.py
@@ -134,7 +134,7 @@ def postprocess(files, process_imports, out_file):
             else:
                 out.write(line)
 
-    with open(out_file, mode='w') as out:
+    with open(out_file, mode='w', encoding='utf8') as out:
         # Put a helper comment and a license blob on top
         out.write("""/* Generated using `./postprocess.py {}`. Do not edit. */