Responsive testimonials grid section using CSS Grid

What are you most proud of, and what would you do differently next time?

This is my second challenge using CSS Grid. Quite proud of how it turned out. I do encounter some difficulty especially positioning the whole container in the center.

What specific areas of your project would you like help with?

I'm still confused is what unit should i use to set the grid template.

.main-container {
        margin: 0 auto;
        display: grid;
        grid-template-columns: 20% repeat(4, 1fr) 20%;
        grid-template-rows: 8rem 1fr 1fr 8rem;
        gap: 2rem;
}