body {
    margin: 0;
    font-family: Arial, sans-serif;
    background: #f5f7fa;
}

/* 🔝 Navbar */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: #1e293b;
    color: white;
    padding: 15px 30px;
}

.navbar a {
    color: white;
    margin-left: 15px;
    text-decoration: none;
}

.navbar a:hover {
    text-decoration: underline;
}

/* 📦 Layout */
.container {
    max-width: 900px;
    margin: 30px auto;
    padding: 10px;
}

/* 📇 Cards */
.card {
    background: white;
    padding: 20px;
    margin-bottom: 25px;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.game-card {
    text-align: center;
}

/* ♟️ Board */
.board-grid {
    display: grid;
    grid-template-columns: 30px repeat(8, 60px);
    grid-template-rows: 30px repeat(8, 60px);
    margin: 20px auto;
    width: max-content;
    border: 6px solid #1e293b;
    border-radius: 10px;
    overflow: hidden;
}

.label {
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    background: #aec8eb;
    color: #1e293b;
}



.cell {
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 30px;
    cursor: pointer;
    transition: 0.2s;
}

.cell:hover {
    transform: scale(1.05);
}

.white {
    background: #e2e8f0;
}

.black {
    background: #475569;
    color: white;
}

.invalid {
    background: #ef4444 !important;
}

/* 🎛️ Buttons */
.controls {
    margin-top: 15px;
}

.btn {
    padding: 10px 15px;
    margin: 5px;
    border: none;
    border-radius: 8px;
    background: #3b82f6;
    color: white;
    cursor: pointer;
}

.btn:hover {
    background: #2563eb;
}

.btn.secondary {
    background: #64748b;
}

.btn.secondary:hover {
    background: #475569;
}

.btn.danger {
    background: #ef4444;
}

.btn.danger:hover {
    background: #dc2626;
}

#queenList {
    list-style: none;
    padding: 0;
}

#queenList li {
    padding: 5px;
    background: #f1f5f9;
    margin: 4px 0;
    border-radius: 6px;
}

.mode-switch {
    margin-bottom: 15px;
}

.mode-switch .btn {
    margin: 5px;
}

.btn.active {
    background: #22c55e;
}