Flex-box

I saw your code and found that you wrapped the entire code inside the class design-container and in gave it height of 650px :-

.design-container {
    display : flex;
    align-items : center;
    height : 650px;
}

You can refrain from restricting the height of parent container, and for centering the content vertically, you can use this approach :-

.design-container {
    display : grid;
    place-content : center;
    min-height : 100vh;
}

Or you can also do :-

.design-container {
    display : flex;
    align-items : center;
    justify-content : center;
    min-height : 100vh;
}

I hope you find this suggestion helpful and it solves your problem, Happy Coding !

You should add this to your body:

body {
    min-height: 100vh;
    justify-content: center;
}

You can also add a box-shadow to your .design

.design {
    box-shadow: 0px 7px 14px #0000001a;
}

I think to center the card you can add min-height:100vh to the body css