Enabled styles.js for classDiagram-v2

src/diagrams/class/styles.js

@@ -12,7 +12,7 @@ const getStyles = options =>
 }
 
 .divider {
-  stroke: $nodeBorder;
+  stroke: ${options.nodeBorder};
   stroke: 1;
 }
 

src/styles.js

@@ -14,7 +14,8 @@ const themes = {
   'flowchart-v2': flowchart,
   sequence,
   gantt,
-  class: classDiagram,
+  classDiagram,
+  'classDiagram-v2': classDiagram,
   stateDiagram,
   state: stateDiagram,
   git,