Html, Css, Desktop first

Looks great :)

Two tips =>

Tip One:

          <p class="why-us">
            Tutorials by industry experts <br />
            Peer & expert code review <br />
            Coding exercises <br />
            Access to our GitHub repos <br />
            Community forum <br />
            Flashcard decks <br />
            New videos every week
          </p>

Instead of using a <p> tag here with breaks, a more screen-reader friendly way would be to use an unordered list, like so =>

<ul class="why-us>
    <li>Tutorials by industry experts</li>
    <li>Peer & expert code review</li>
    <li>Coding exercises</li>
    <li>Access to our GitHub repos</li>
    <li>Community forum</li>
    <li>Flashcard decks</li>
    <li>New videos every week</li>
</ul>

Tip Two:

<div class="sign-up-button">Sign Up</div>

Can't be focused by a keyboard. A more accessible way could be using the anchor tag.

<a role="button" href="">Sign Up</a>

You can then give it an a:focus-visible { } pseudo class for people using the tab key through a website.

Cheers :)