My portfolio project now

I don’t know how to make my viewport and my welcome-section have the same height.

This is my link https://codepen.io/madu-munachiso-stanley/pen/xxbgWPp

I believe you want your header and welcome-section to take 100% of viewport height, is that correct?
The one way to achieve it:

header: {
  height: 94px;
}
#welcome-section {
 height: calc(100vh - 94px);
}

Thank you, but it didn’t work.

Add:

* {
  box-sizing: border-box;
}

Homework: https://dev.to/neshaz/how-to-treat-your-css-elements-the-box-sizing-property-13p3