In fusion-acquia-slate-style.css, I noted three problems :

Problem 1) h1 has the style :
font-size: 169.23;

It should logically be:
font-size: 169.23%; (was missing the %)

h2, for example, is font-size: 138.46%;

Problems 2) and 3)

.node-unpublished and .preview .node, for this theme (acquia_slate), should be dark gray (such as 444) and not fff4f4 and fffea (which is beige-cream like).