* {
    box-sizing: border-box;
}

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

main {
    display: flex;
    height: 100%;
    width: 100%;
    flex-wrap: wrap;
}

.selector {
    flex-grow: 1;
    display: flex;
    max-width: 100vw;
    width: 50vmax;

    border: 0;
    margin: 0;
    padding: 0;
    background: #000;

    background-size: cover;

    align-items: center;
    justify-content: center;

    overflow: hidden;
    position: relative;
}

.selector img {
    width: 100%;
    height: 100%;
    object-fit: cover;

    position: absolute;
    top: 0;
    left: 0;
}

#intro {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;

    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2;
    padding: 2em;

    background: #000;
    border: 0;
}

#intro div {
    background: #f7f7f7;
    color: #111;
    font-family: 'Courier New', Courier, monospace;
    text-align: center;

    width: max-content;
    max-width: 80ch;

    padding: 1em;

    display: flex;
    align-items: center;
    flex-direction: column;
}

kbd {
    padding: 0.5ch;
    background: #eee;
    border: 1px solid #ccc;
    border-radius: 0.5ch;
}

#intro button {
    width: max-content;
    font-size: 1.25em;
    padding: 0.5em;

    margin: 0.5em 0;
}

#intro p {
    line-height: 1.6;
}

#shadow {
    position: fixed;
    display: flex;
    top: 1000vh;
    width: max-content;
    height: 100vh;
}