Html, Css, flexbox

Hi there 👋

Congratulate on finishing your project 🎉. The design looks beautiful 😃.

I will try my best to answer you. About your code, in CSS this code is enough to reset the padding and margin of element because of inheritance, * selector applies to all the elements

*, 
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

And also setting font family inside body selector is the best way compared to the others

body { font-family: var(--font-primary); }

1. Let's about naming classes there is a great technique that is popular among frontend devs called BEM method. I give you a nice cheatsheet to learn more about it click on this 🎁
2. Adding SVG icons is not recommended, instead use icon packs like ionic ones or google material icons. You just import it like importing CSS or js files. Search some tutorials about it on youtube 👍
3. About your design its perfect

Happy coding ☕

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