style.css

* {
    box-sizing: border-box;
    padding: 0;
    margin: 0;
    font-family: sans-serif;
}

html,
body {
    height: 100%;
}

body {
    padding: 32px;
}

body,
#container {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

#container {
    position: relative;
    gap: 0.4rem;

    width: 640px;
    height: 640px;
    max-width: 100%;
    max-height: 100%;

    border: 2px dashed #D1D5DB;
    border-radius: 0.75rem;
    overflow: hidden;
    cursor: pointer;
    margin: 1rem;

    background-size: 100% 100%;
    background-position: center;
    background-repeat: no-repeat;
    font-size: 18px;
}