body {
    margin: 0px;
    background: var(--bg-body, #F4F6F8);
    color: var(--text-primary, #1C1E21);
    font-family: 'Inter', 'Arial', sans-serif;
    transition: all 0.3s ease;
}

:root {
    --bg-body: #F4F6F8;
    --bg-header: #FFFFFF;
    --text-primary: #1C1E21;
    --text-secondary: #4E5D6C;
    --btn-primary: #C8943B;
    --btn-hover: #C8943B;
    --link-color: #4A4A4A;
    --border-color: #D0D7DE;
    --highlight: #7E57C2;
    --shadow-sm: 0 2px 8px rgba(28, 30, 33, 0.1);
    --shadow-hover: 0 4px 12px rgba(28, 30, 33, 0.15);
}

[data-theme="dark"] {
    --bg-body: #0D1117;
    --bg-header: #161B22;
    --text-primary: #E6EDF3;
    --text-secondary: #8B949E;
    --border-color: #30363D;
    --highlight: #9B6BFF;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-hover: 0 4px 12px rgba(0, 0, 0, 0.4);
}

header {
    height: 50px;
    background: var(--bg-header);
    border: 1px solid var(--border-color);
    width: 960px;
    margin: 0px auto;
    text-align: center;
    box-shadow: var(--shadow-sm);
    border-radius: 8px;
    transition: all 0.3s ease;
}

header h1 {
    margin: 5px;
}

header h1 {
    color: var(--text-primary);
}

header h1 span {
    color: var(--btn-primary);
}

section {
    text-align: center;
    width: 960px;
    background: var(--bg-header);
    border: 1px solid var(--border-color);
    margin: 20px auto;
    border-radius: 8px;
    padding: 1rem;
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
}

main {
    -webkit-perspective: 300;
    perspective: 300;
    width: 960px;
    background: var(--bg-header);
    border: 1px solid var(--border-color);
    height: 550px;
    margin: 20px auto;
    border-radius: 8px;
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
}

.board {
    text-align: center;
    -ms-transform: rotateX(8deg);
    -webkit-transform: rotateX(8deg);
    transform: rotateX(8deg);
    width: 500px;
    height: 456px;
    border: 1px solid black;
    margin: 20px auto;
}

.row {
    height: 12.5%;
}

.cell {
    width: 12.5%;
    height: 12.5%;
    float: left;
    background-color: #fff;
}

.cell:hover {
    background-color: var(--highlight);
    opacity: 0.7;
    transition: all 0.3s ease;
}

.cell-white {
    background-color: #fff;
}

.cell-black {
    background-color: #0f0f0f;
}

.selected {
    box-sizing: border-box;
    -moz-box-sizing: border-box;
    -webkit-box-sizing: border-box;
    border: 2px solid red;
}

.highlight {
    background-color: var(--highlight);
    cursor: pointer;
    transition: all 0.3s ease;
}

.board img {
    width: 90%;
    cursor: pointer;
}

#white-counter,
#black-counter {
    display: inline;
    margin-right: 5px
}

#white-counter,
#black-counter {
    color: var(--text-primary);
}

#white-counter span,
#black-counter span {
    color: var(--btn-primary);
    font-weight: bolder;
    font-size: 30px;
}

footer {
    background: var(--bg-header);
    border: 1px solid var(--border-color);
    width: 960px;
    margin: 0px auto;
    text-align: center;
    border-radius: 8px;
    padding: 1rem;
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
}

footer li {
    display: inline;
    margin-top: -20px;
}

footer span {}

footer img {
    height: 30px;
}

.btn {
    position: relative;
    vertical-align: top;
    width: 150px;
    height: 45px;
    margin: 10px;
    padding: 0;
    font-size: 22px;
    font-family: 'Inter', 'Arial', sans-serif;
    color: white;
    text-align: center;
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.25);
    background: var(--btn-primary);
    border: 0;
    border-radius: 8px;
    cursor: pointer;
    box-shadow: var(--shadow-sm), 0 2px 4px rgba(200, 148, 59, 0.3);
    transition: all 0.3s ease;
}

.btn:active {
    transform: translateY(2px);
    outline: none;
    box-shadow: var(--shadow-sm);
}

.btn:hover {
    background: var(--btn-hover);
    box-shadow: var(--shadow-hover), 0 4px 8px rgba(200, 148, 59, 0.4);
    transform: translateY(-2px);
}