Allow underscores in CSS variable names

* lisp/textmodes/css-mode.el (css-nmchar-re): Allow underscores in
variable names (and in identifiers in general).

* test/manual/indent/css-mode.css: Add some examples of variable names
with underscores in them.

* test/manual/indent/less-css-mode.less: Add some examples of variable
names with underscores in them.

* test/manual/indent/scss-mode.scss: Add some examples of variable
names with underscores in them.

1 files changed, 10 insertions, 0 deletions

diff --git a/test/manual/indent/less-css-mode.less b/test/manual/indent/less-css-mode.less
index 36c037450cc..b40a2362e28 100644
--- a/test/manual/indent/less-css-mode.less
+++ b/test/manual/indent/less-css-mode.less
@@ -1,3 +1,13 @@
+@var-with-dashes: #428bca;
+@var_with_underscores: 10px;
+@_var-starting-with-underscore: none;
+
+body {
+    background: @var-with-dashes;
+    padding: @var_with_underscores;
+    display: @_var-starting-with-underscore;
+}
+
 .desktop-and-old-ie(@rules) {
     @media screen and (min-width: 1200) { @rules(); }
     html.lt-ie9 &                       { @rules(); }