Added instructions for the default CSS properties that are required

README.md

@@ -8,11 +8,27 @@ $ npm install @q42/floating-focus-a11y --save
 ```
 
 ## Usage
+Import the package and instantiate the class on page load:
 ```javascript
 import { FloatingFocus } from '@q42/floating-focus-a11y';
 new FloatingFocus();
 ```
 
+Define a default outline and outline-offset. Either of these values can be overruled per component:
+```css
+// Default outline value, which will be applied to all elements receiving focus, this is a required step.
+.floating-focus-enabled *:focus {
+  outline: dodgerblue solid 2px;
+  outline-offset: 8px;
+}
+
+// Give all buttons a green focus state instead of dodgerblue, this is optional in case it's needed.
+[type="button"]:focus {
+  outline: green dashed 1px;
+  outline-offset: 4px;
+}
+```
+
 ## Develop
 ```bash
 $ npm run build