make compatibility list header sticky

docs/release-notes.md

@@ -18,6 +18,7 @@
 
 * For the web UI:
   * Updated the JSON validator and Content Patcher schema for `.tmx` support.
+  * The mod compatibility page now has a sticky table header.
 
 * For SMAPI/tool developers:
   * The SMAPI log now prefixes the OS name with `Android` on Android.

src/SMAPI.Web/wwwroot/Content/css/mods.css

@@ -86,6 +86,11 @@ table.wikitable > caption {
     font-size: 0.9em;
 }
 
+#mod-list thead tr {
+    position: sticky;
+    top: 0;
+}
+
 #mod-list th.header {
     background-repeat: no-repeat;
     background-position: center right;