body {
    font-family: "Helvetica Neue",
    Arial,
    "Hiragino Kaku Gothic ProN",
    "Hiragino Sans",
    "BIZ UDPGothic",
    Meiryo,
    sans-serif;
    padding-top: 2em;
}
article {
    display: flex;
    justify-content: center;
}
.status {
    margin-bottom: 20px;
    font-size: 1.2em;
}
.status table {
    width: 100%;
}
.status td:first-child {
    text-align: left;
}
.status td:last-child {
    text-align: right;
}
.black-turn {
    text-align: center;
    color: #fff;
    background-color: #000;
    border: 1px solid #000;
}
.white-turn {
    text-align: center;
    color: #000;
    border: 1px solid #000;
}
.board {
    border-top: 10px #804012 solid;
    border-right: 10px #66330e solid;
    border-bottom: 10px #4d260b solid;
    border-left: 10px #994c15 solid;
}
.board table {
    width: 100%;
    border: 1px solid #000;
    border-collapse: collapse;
    background-color: #008000;
}
.board td {
    border: 1px solid #000;
    width: 12%;
}
.board td a {
    display: block;
}
.board td a:hover {
    background-color: rgba(255,255,255 ,.5);
}
.board a::before, .board span::before{
    content: "";
    display: inline-block; 
    padding-top: 92%;
}
.board span {
    position: relative;
    display: inline-block;
    width: 100%;
}
.board span::after {
    content: "";
    display: inline-block;
    width: 70%;
    height: 70%;
    border-radius: 50%;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    -webkit-transform: translate(-50%, -50%);
    -ms-transform: translate(-50%, -50%);
}
.black::after {
    background-color: #111;
    box-shadow: 2px 2px 1px rgba(0,0,0, .7);
}
.white::after {
    background-color: #fff;
    box-shadow: 2px 2px 1px rgba(0,0,0, .7);
}
.board p {
    font-weight: bold;
}
.buttons {
    margin-top: 30px;
}
.buttons button {
    font-size: 1.2em;
}
.buttons table {
    width: 100%;
    text-align: center;
}
.result {
    color: #fff;
    font-weight: bold;
    text-align: center;
    background-color: #f00;
    border: 1px solid #f00;
}

@media all and (min-width: 1024px) {
    .container {
        width: 100%;
        max-width: 540px;
    }
}
@media all and (max-width: 1024px) {
    .container {
        width: 100%;
        margin: 0 10px;
    }
    .board a::before, .board span::before{
        content: "";
        display: inline-block; 
        padding-top: 94%;
    }
    .board td a {
        background-color: rgba(255,255,255 ,.5);
    }
    .status, .buttons button {
        font-size: 2em;
    }
}