* [misc] add style::var helper to set css var.

lib/zin/core/style.class.php

@@ -27,7 +27,7 @@ class style extends \zin\utils\dataset implements iDirective
     public function __call(string $name, array $args): style
     {
         $value = empty($args) ? true : (count($args) === 1 ? $args[0] : $args);
-        return $this->setVal($name, $value);;
+        return $this->setVal($name, $value);
     }
 
     /**
@@ -68,6 +68,16 @@ class style extends \zin\utils\dataset implements iDirective
         if($class) $node->setProp('class', $class);
     }
 
+    public function var(string|array $nameOrMap, mixed $value = null): style
+    {
+        if(is_array($nameOrMap))
+        {
+            foreach($nameOrMap as $name => $val) $this->setVal('--' . $name, $val);
+            return $this;
+        }
+        return $this->setVal('--' . $nameOrMap, $value);
+    }
+
     /**
      * Magic static method for style property value.
      *
@@ -108,6 +118,10 @@ class style extends \zin\utils\dataset implements iDirective
         {
             $value .= 'px';
         }
+        elseif(is_string($value) && str_starts_with($value, '--'))
+        {
+            $value = 'var(' . $value . ')';
+        }
 
         return is_string($value) ? $value : (string)$value;
     }