I am making a small one-page website, consisting of 3 sections and a contact form. I want to allow the client to edit each of the sections/blocks using WYSIWYG. Preferably they should be edited in-place, like in the discontinued Zimplit. The contact form should provide sending e-mails to the client. There will be no other pages, so the whole admin panel is not necessary.
It has to be in PHP, no MySQL, no PostgreSQL, and it has to be open source.
Wordpress, Drupal, CMSMadeSimple are too big for this.