Fix bug in css--mdn-find-symbol

* lisp/textmodes/css-mode.el (css--mdn-find-symbol): Skip whitespace
before skipping word characters.
test/lisp/textmodes/css-mode-tests.el (css-mdn-symbol-guessing): Add
regression test.

2 files changed, 6 insertions, 3 deletions

diff --git a/lisp/textmodes/css-mode.el b/lisp/textmodes/css-mode.el
index 19746c68e6a..cd86db639ab 100644
--- a/lisp/textmodes/css-mode.el
+++ b/lisp/textmodes/css-mode.el
@@ -1190,8 +1190,10 @@ to look up will be substituted there."
   "A helper for `css-lookup-symbol' that finds the symbol at point.
 Returns the symbol, a string, or nil if none found."
   (save-excursion
-    ;; Skip backward over a word first.
-    (skip-chars-backward "-[:alnum:] \t")
+    ;; Skip any whitespace between the word and point.
+    (skip-chars-backward "- \t")
+    ;; Skip backward over a word.
+    (skip-chars-backward "-[:alnum:]")
     ;; Now skip ":" or "@" to see if it's a pseudo-element or at-id.
     (skip-chars-backward "@:")
     (if (looking-at css--mdn-symbol-regexp)
diff --git a/test/lisp/textmodes/css-mode-tests.el b/test/lisp/textmodes/css-mode-tests.el
index 5372c37a179..d601f43002a 100644
--- a/test/lisp/textmodes/css-mode-tests.el
+++ b/test/lisp/textmodes/css-mode-tests.el
@@ -226,7 +226,8 @@
                   ("a:v" "isited" ":visited")
                   ("border-" "color: red" "border-color")
                   ("border-color: red" ";" "border-color")
-                  ("border-color: red; color: green" ";" "color")))
+                  ("border-color: red; color: green" ";" "color")
+                  ("  border-collapse " ": collapse;" "border-collapse")))
     (with-temp-buffer
       (css-mode)
       (insert (nth 0 item))