css-mode: Don't confuse variable names with class names

This fixes highlighting for class names that contain --, for example:

.foo--bar {
    display: none;
}

* lisp/textmodes/css-mode.el (css--font-lock-keywords): Make regular
  expression stricter.

1 files changed, 1 insertions, 1 deletions

diff --git a/lisp/textmodes/css-mode.el b/lisp/textmodes/css-mode.el
index 9022ab7c3fb..0a4cb998b57 100644
--- a/lisp/textmodes/css-mode.el
+++ b/lisp/textmodes/css-mode.el
@@ -896,7 +896,7 @@ cannot be completed sensibly: `custom-ident',
                      ;; No face.
                      nil)))
     ;; Variables.
-    (,(concat "--" css-ident-re) (0 font-lock-variable-name-face))
+    (,(concat (rx symbol-start) "--" css-ident-re) (0 font-lock-variable-name-face))
     ;; Properties.  Again, we don't limit ourselves to css-property-ids.
     (,(concat "\\(?:[{;]\\|^\\)[ \t]*\\("
               "\\(?:\\(" css-proprietary-nmstart-re "\\)\\|"