refactor: add SSR support

Author: mrholek

src/getColor.ts

@@ -7,7 +7,7 @@
 
 import getStyle from './getStyle'
 
-const getColor = (rawProperty: string, element = document.body) => {
+const getColor = (rawProperty: string, element?: Element) => {
   const property = `--${rawProperty}`
   const style = getStyle(property, element)
   return style ? style : rawProperty

src/getStyle.ts

@@ -5,8 +5,18 @@
  * --------------------------------------------------------------------------
  */
 
-const getStyle = (property: string, element = document.body) => {
-  return window.getComputedStyle(element, null).getPropertyValue(property).replace(/^\s/, '')
+const getStyle = (property: string, element?: Element) => {
+  if (typeof window === 'undefined') {
+    return
+  }
+
+  if (typeof document === 'undefined') {
+    return
+  }
+
+  const _element = element ?? document.body
+
+  return window.getComputedStyle(_element, null).getPropertyValue(property).replace(/^\s/, '')
 }
 
 export default getStyle