diff --git a/after/syntax/css/css-writing-modes-3.vim b/after/syntax/css/css-writing-modes-3.vim
index d13e3ca..dbda2e5 100644
--- a/after/syntax/css/css-writing-modes-3.vim
+++ b/after/syntax/css/css-writing-modes-3.vim
@@ -1,7 +1,8 @@
-" TODO: create cssWritingModeProp group and cssWritingModeAttr group
-syn match cssFontProp contained "\<text-\(orientation\|combine-horizontal\)\>"
-syn match cssFontProp contained "\<writing-mode\>"
-syn keyword cssFontAttr contained before after mixed isolate plaintext
-syn match cssFontAttr contained "\<\(upright\|sideways\(-right\|-left\)\=\|use-glyph-orientation\)\>"
-syn match cssFontAttr contained "\<isolate-override\>"
-syn match cssFontAttr contained "\<\(horizontal-tb\|vertical-\(rl\|lr\)\)\>"
+if !hlexists('cssWritingModeProp')
+  syn match cssFontProp contained "\<text-\(orientation\|combine-horizontal\)\>"
+  syn match cssFontProp contained "\<writing-mode\>"
+  syn keyword cssFontAttr contained before after mixed isolate plaintext
+  syn match cssFontAttr contained "\<\(upright\|sideways\(-right\|-left\)\=\|use-glyph-orientation\)\>"
+  syn match cssFontAttr contained "\<isolate-override\>"
+  syn match cssFontAttr contained "\<\(horizontal-tb\|vertical-\(rl\|lr\)\)\>"
+endif