apply method
Implementation
@override
void apply(MarkupRenderObject root) {
var html = root.children.findWhere((c) => c.tag == 'html')?.node ?? root;
var head = html.children.findWhere((c) => c.tag == 'head')?.node;
if (head == null) {
html.children.insertAfter(head = html.createChildRenderObject()..tag = 'head');
}
applyHead(head);
}