body {
        font-family: 'Segoe UI', sans-serif;
        margin: 0;
        background: #f9f9f9;
        color: #333;
    }

    .navbar {
        background: #111;
    }

    .navbar-brand {
        font-weight: bold;
        font-size: 1.5rem;
        background: linear-gradient(to right, #f39c12, #e74c3c);
        -webkit-background-clip: text;
        -webkit-text-fill-color: transparent;
    }

    .nav-link {
        color: #fff !important;
    }

    .navbar .btn.nav-link {
        background: transparent;
        border: none;
        padding: 0;
        font-weight: 500;
        font-size: 1rem;
        color: white;
        cursor: pointer;
        text-decoration: underline;
    }

    .navbar .btn.nav-link:hover {
        color: #ffc107;
        /* Bootstrap warning color */
    }


    .hero {
        background: linear-gradient(to right, #f39c12, #e67e22);
        color: white;
        padding: 80px 20px;
        text-align: center;
    }

    .hero h1 {
        font-size: 2.5rem;
        font-weight: bold;
    }

    .hero p {
        font-size: 1.2rem;
        margin-top: 15px;
    }

    .chessboard {
        display: grid;
        grid-template-columns: repeat(8, 1fr);
        gap: 2px;
        max-width: 600px;
        margin: 40px auto;
        aspect-ratio: 1 / 1;
        border-radius: 8px;
        overflow: hidden;
        box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
    }

    .square {
        position: relative;
        display: flex;
        flex-direction: column;
        justify-content: center;
        align-items: center;
        font-size: 12px;
        font-weight: bold;
        padding: 4px;
        cursor: pointer;
        transition: all 0.2s ease-in-out;
        text-align: center;
    }

    .square:hover {
        transform: scale(1.05);
        z-index: 1;
        box-shadow: 0 0 10px rgba(0, 0, 0, 0.3);
    }

    .white {
        background-color: #f0d9b5;
    }

    .black {
        background-color: #b58863;
    }

    .reserved {
        background-color: #2e7d32 !important;
        color: white;
    }

    .sold {
        background-color: #c62828 !important;
        color: white;
    }

    .field-number {
        position: absolute;
        font-size: 10px;
        bottom: 4px;
        right: 6px;
        opacity: 0.7;
    }

    .field-text {
        font-size: 10px;
        word-wrap: break-word;
        text-align: center;
    }

    footer {
        text-align: center;
        padding: 30px 15px;
        background: #111;
        color: #ccc;
        font-size: 14px;
    }

    @media(max-width: 768px) {
        .hero h1 {
            font-size: 2rem;
        }

        .chessboard {
            width: 95%;
        }
    }

    .chessboard-container {
        position: relative;
        background: url('../images/bitcoin_chess_background.png') no-repeat center center;
        background-size: cover;
        padding: 20px;
    }