body {
    margin: 0;
    padding: 0;

    background-image: url("./img/sora.jpg");
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    background-attachment: fixed;

    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    font-family: "Helvetica Neue", Arial, "Hiragino Kaku Gothic ProN", "Hiragino Sans", Meiryo, sans-serif;
    -webkit-font-smoothing: antialiased;
}