fix(css) variable '_' detection #3823 (#3863)

Author: akhtarmdsaad

CHANGES.md

@@ -41,6 +41,7 @@ Core Grammars:
 - fix(swift) `warn_unqualified_access` is an attribute [Bradley Mackey][]
 - enh(swift) macro attributes are highlighted as keywords [Bradley Mackey][]
 - enh(stan) updated for version 2.33 (#3859) [Brian Ward][]
+- fix(css) added '_'  css variable detection [Md Saad Akhtar][]
 
 Dev tool:
 
@@ -64,7 +65,7 @@ Dev tool:
 [Nicholas Thompson]: https://github.com/NAThompson
 [Yasith Deelaka]: https://github.com/YasithD
 [Brian Ward]: https://github.com/WardBrian
-
+[Md Saad Akhtar]: https://github.com/akhtarmdsaad
 
 ## Version 11.8.0
 

src/languages/lib/css-shared.js

@@ -38,7 +38,7 @@ export const MODES = (hljs) => {
     },
     CSS_VARIABLE: {
       className: "attr",
-      begin: /--[A-Za-z][A-Za-z0-9_-]*/
+      begin: /--[A-Za-z_][A-Za-z0-9_-]*/
     }
   };
 };

test/markup/css/variables.expect.txt

@@ -7,3 +7,8 @@
  <span class="hljs-attr">--textBlue</span>: blue;
  <span class="hljs-attribute">color</span>: <span class="hljs-built_in">var</span>(--textBlue);
 }
+
+<span class="hljs-selector-tag">body</span> {
+ <span class="hljs-attr">--_margin-top</span>: <span class="hljs-number">1rem</span>;
+ <span class="hljs-attribute">margin-top</span>: <span class="hljs-built_in">var</span>(--_margin-top);
+}

test/markup/css/variables.txt

@@ -7,3 +7,9 @@ body {
  --textBlue: blue;
  color: var(--textBlue);
 }
+
+body {
+ --_margin-top: 1rem;
+ margin-top: var(--_margin-top);
+}
+