diff --git a/.github/workflows/validate-css.yml b/.github/workflows/validate-css.yml
new file mode 100644
index 0000000..b325b82
--- /dev/null
+++ b/.github/workflows/validate-css.yml
@@ -0,0 +1,13 @@
+name: Validate CSS
+
+on: [push, pull_request, workflow_dispatch]
+
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: actions/setup-node@v6
+        with:
+          node-version: 26
+      - run: npx -y csstree-validator css/flat-remix.css
diff --git a/css/flat-remix.css b/css/flat-remix.css
index 2751d93..3501985 100644
--- a/css/flat-remix.css
+++ b/css/flat-remix.css
@@ -188,7 +188,7 @@ code, pre {
     line-height: 2em;
     cursor: auto;
     user-select: text;
-    -webkit-touch-callout: text;
+    -webkit-touch-callout: default;
     -webkit-user-select: text;
 }
 
@@ -213,7 +213,7 @@ textarea, select {
     font-weight: bold;
     cursor: text;
     user-select: text;
-    -webkit-touch-callout: text;
+    -webkit-touch-callout: default;
     -webkit-user-select: text;
 }
 
@@ -494,6 +494,6 @@ input[type=reset]:active, input[type=reset].active,
 .selectable {
     cursor: auto;
     user-select: text;
-    -webkit-touch-callout: text;
+    -webkit-touch-callout: default;
     -webkit-user-select: text;
 }