body {
    font-family: 'Roboto', sans-serif;
    padding: 0;
    margin: 0;
    -webkit-box-sizing: border-box;
       -moz-box-sizing: border-box;
            box-sizing: border-box;
}
.container {
    max-width: 1200px;
    margin: 40px auto;
    padding: 40px 20px;
    background-color: whitesmoke;
    justify-content: center;
}
header {
    padding: 0 0 30px 0;
    font-size: 30px;
}
#game {
    background-color: #fafafa;
    width: 70vmin;
    height: 70vmin;
    box-shadow: 0 0 25px rgba(0,0,0,.2);
    margin: 0 auto;
    display: grid;
    grid-template-rows: repeat(3, 1fr);
    grid-template-columns: repeat(3, 1fr);
}
.cross {
    background-image: url("./cross.svg");
    background-size: 50%;
    background-position: center;
    background-repeat: no-repeat;
}
.circle {
    background-image: url("./circle.svg");
    background-size: 60%;
    background-position: center;
    background-repeat: no-repeat;
}