It may be too much for moms, but maybe the html document includes the content, but a chrome extension does the work and presents the secret in the extension pop

It may be too much for moms, but maybe the html document includes the content, but a chrome extension does the work and presents the secret in the extension popup. - attack surface area drastically reduced. only one MITM matters now, the extension installation - requires great extension UX, to help dads know where to click less portable than just a document, but perhaps a nice middle ground