curl --request GET \
  --url https://api.hubapi.com/content/api/v2/layouts/{layoutId}/buffer

{
  "id": "<string>",
  "label": "<string>",
  "path": "<string>",
  "category_id": "<string>",
  "created": 123,
  "updated": 123,
  "deleted_at": 123,
  "body_class": "<string>",
  "body_css_id": "<string>",
  "layout_data": {},
  "custom_head": "<string>",
  "include_default_custom_css": true,
  "enable_domain_stylesheet": true,
  "attached_stylesheets": [
    "<string>"
  ]
}