Body size / What code is required?

Hi everyone.
I added border radius to this code and made the bottom part as I wanted.
But I can’t fix the top part.
What codes should I add to make the upper part look just like the lower part?
like : top-height-size: -30%; ? but this not working

body:before {
display: inline-block;
border-radius: 15px;
width: 1125px;
min-height: 100%;
height: inherit;
background-color: #fff;
content: " ";
position: fixed;
left: 50%;
right: 0;
transform: translate(-50%, 0);

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