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;
    text-align: center;
}

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

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

.white-player {
    .board-cell:hover .overlay {
        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;
    }
}

.split-wrapper {
    display: flex;
    @media screen and (max-width: 640px) {
        flex-direction: column;
    }
    width: 100%;
}

.split-item {
    flex-grow: 1;
    box-sizing: border-box;
}

.split-wrapper form {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 10px;

    input {
        margin-top: 20px;
        padding: 5px;
        padding-left: 10px;
        padding-right: 10px;
        border: none;
        outline: none;
        width: 100%;
        max-width: 300px;
    }

    input[type="radio"] {
        opacity: 0;
        width: 0px;
        height: 0px;

        &:checked ~ label {
            color: tomato;
            transition: color .25s;
        }
    }

    input[type="submit"] {
        padding: 10px;
        background-color: tomato;
        color: white;

        &:focus, &:hover {
            background-color: inherit;
            color: tomato;
            transition: background-color .25s, color .25s;
        }
    }

    input[type="text"] {
        background-color: inherit;
        border-bottom: solid tomato;
        border-width: 2px;

        &:focus {
            border-width: 3px;
            transition: background-color .25s, border-width .25s;
        }

        height: 3em;
        box-sizing: border-box;
        display: block;
    }
    
    .radio-parent {
        display: flex;
        margin-top: 20px;
        width: 100%;
        max-width: 300px;
    }

    .radio-wrapper {
        flex-grow: 1;
        display: inline-block;
        text-align: center;
    }
}