All things tested on:
Firefox/linux/maxmizied window/1920x1080

• I personally find it hard to read on a wide screen (standard 1920x1080). maybe you could center your content a bit?
• You have to click precisely on the Menu bar links/text, given that the menu bar is spaced out quiet a bit, that is somewhat cumbersome, this is enhanced by the fact that the whole bar appears to be "clickable" (cursor changes to pointer on mouse-over)
• The Header section with the clouds is pretty tall, the content starts way at the bottom. Switching between the site sections, although the content switched instantly, was not obvious to me immediately.
• The URL in the browser does not represent where on the site you are, you cannot i.E. link directly to your "skills" like so: portfolio.liftoff-ka.repl.co/skills
• having some of the text on your page center, whilst other parts are not is also inconsistant

Regarding the Content:
Your Skills are just Pictures, maybe try to outline where your strength are?
Also No recuriter/HR Person will know what those logos mean, write that stuff out ;)

That's it for now.
please dont be discouraged by what I just wrote, I myself struggle with things like these, they are just more apparent to an outsider :)

Happy Hacking
^C