Flexbox

[altabz]

which is better make the entire body of your html flexbox:

 body {
    margin: 0;
    display: flex;
    min-height: 100vh; 
}

or create flexbox container that will occupy the entire body?

body, html {
    margin: 0;
    height: 100%;
}

.container {
    display: flex;
    min-height: 100vh;
    justify-content: center;
    align-items: center;
    background-color: #f0f0f0;
}

!