:root {
    --bg-color: #f4f4f9;
    --text-color: #333;
    --header-bg: #2c3e50;
    --header-text: #ecf0f1;
    --accent: #e74c3c;
}
body {
    font-family: system-ui, -apple-system, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    padding: 0;
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}
header {
    background-color: var(--header-bg);
    color: var(--header-text);
    padding: 1rem 0;
    text-align: center;
}
nav ul {
    list-style: none;
    padding: 0;
    display: flex;
    justify-content: center;
    gap: 15px;
}
nav a {
    color: var(--header-text);
    text-decoration: none;
    font-weight: bold;
}
nav a:hover {
    color: var(--accent);
}
main {
    max-width: 800px;
    margin: 2rem auto;
    padding: 0 1rem;
    flex-grow: 1;
}
footer {
    text-align: center;
    padding: 1rem 0;
    background-color: var(--header-bg);
    color: var(--header-text);
    margin-top: auto;
}
.chessboard {
    display: grid;
    grid-template-columns: repeat(8, 40px);
    grid-template-rows: repeat(8, 40px);
    margin: 2rem auto;
    border: 4px solid var(--text-color);
    width: 320px;
}
.cell {
    width: 40px;
    height: 40px;
}
.cell.black { background-color: #769656; }
.cell.white { background-color: #eeeed2; }