The highlightet YAML file at https://kubernetes.io/docs/tasks/debug/debug-cluster/monitor-node-health/#using-kubectl contains an empty line between every two lines.
apiVersion: apps/v1
kind: DaemonSet
metadata:
name: node-problem-detector-v0.1
namespace: kube-system
labels:
and so on.
There shall be no empty lines shown in the browser.