Function getWithFallback

getWithFallback<T extends Record<string, string | number>>(
fallback: T,
elt?: Element,
): T
Computes the styles for elt (or defaults to document.body) using fallback as a set of default values.
```
// Fetch styles
const styles = getWithFallback({
 my_var: `red`
}, element);

// Access --my-var, or if it doesn't exist returns 'red'
styles.my_var;
```
Hyphen case (eg 'my-var') is a common way of delimiting words in CSS variables, but can't be (elegantly) used in object properties. Instead, use '_' in the object key, which is replaced with '-'.

The leading '--' is not needed either.
Type Parameters
- TextendsRecord<string, string | number>
Parameters
- fallback: T
- Optionalelt: Element
Returns T