SE and screen readers ignore MOST CSS ( but that not relevant to the example I gave). Maybe OLD cell phones? Still a USER can choose to disable images, .js, and/or CSS at her digression. This is why its best practice to think content first.
The above suggestion was merely a personal preference; when I code I to to make the page SEMANTIC, then 'followable' as pure text (CSS disabled, as it might have been seen in '98)... then make LAYOUT/bg in CSS and make it as cross browser friendly as I can and so that all the content is still readable and accessible, then I flesh it out with bg/graphics, etc (my art direction/ graphic design), then I add any other bells and whistles or effects, finally I will add polyfill. This way Ia m always sure the page gracefully degrades.
I would have to see the working site ( there is only one page), but I would go with what I suggested above.
as you dont have a loto of content its hard to tell.. but I am really not sure that 'hello', 'let's talk' , 'let's work' (and perhaps that should be say 'my work history' anyway )are h4s
Tip: imagine you are witting your content as an outline for a presentation or report. If it's not a heading of a sun section then... it's not an Hx.