coder problems:
divitis (great for moving stuff as "chunks")
if the code isn't being used just delete it

classitis
is you only have one h1, just target the h1 directly in the css

semantic code
always have some kind of text tags on your html 

css grid (not flexbox)
there is always another way, meaning flex boxes aren't needed

viewport width (#wrapper)

RWD responsive web design
three things you can get wrong
-image (max-width 100%)
-all texts would be em or rem (not pixels)
-media@ are there for a reason (play with them and change them accordingly)
(in the top corner it will say how wide the page is using the media query, it can do all kinds of things and solve alot of problems)

code is hard
-if your stuck, hit save and take a walk before coming back

@media (html font size etc
proportionately scale everything down

object-fit

max-height: 100%;
    max-width: 100%;