body {
    margin: 0;
    overflow: hidden;
    background: black;
    font-family: Arial, sans-serif;
    color: white;
}

#game {
    display: none;
    background: #050505;
}

#menu {
    position: absolute;
    width: 100%;
    height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    background:
    linear-gradient(
    rgba(0,0,0,.7),
    rgba(0,0,0,.9)
    ),
    url("https://images.unsplash.com/photo-1511497584788-876760111969");
    background-size: cover;
}

h1 {
    font-size: 45px;
}

button {
    padding: 15px 35px;
    background: #222;
    color:white;
    border:1px solid white;
    cursor:pointer;
    font-size:20px;
}

button:hover {
    background:white;
    color:black;
}