GoServer/public/scss/main.scss

$background-grey: #f4f4f4;

@mixin board-cell($size) {
    padding: 100%/$size/2;
}

h1, h2, h3, h4, h5, h6 {
    font-family: "Indie Flower", serif;
}

h1 {
    font-size: 5em;
    margin: 0px;
    text-align: center;
}

body {
    font-family: "Raleway", sans-serif;
    margin: 0px;
    background-color: $background-grey;
}

.content-wrapper {
    max-width: 750px;
    margin: auto;
}

.board {
    background-color: tomato;
    padding: 20px;
    max-width: 500px;
    margin: auto;
    border-radius: 10px;
}

.black-player .overlay {
    &:hover {
        background-color: black;
    }
}

.white-player .overlay {
    &:hover {
        background-color: white;
    }
}

.board-cell {
    display: inline-block;
    position: relative;
    @include board-cell(9);

    .overlay {
        position: absolute;
        box-sizing: border-box;
        top: 10%;
        left: 10%;
        width: 80%;
        height: 80%;
        border-radius: 50%;
        transition: background-color .25s;
    }

    &.small {
        @include board-cell(9);
    }

    &.medium {
        @include board-cell(13);
    }

    &.large {
        @include board-cell(19);
    }
}

.black-cell {
    .overlay {
        background-color: black;
    }
}

.white-cell {
    .overlay {
        background-color: white;
    }
}