* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
}

.container {
    background: white;
    border-radius: 20px;
    padding: 30px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    text-align: center;
}

h1 {
    color: #333;
    margin-bottom: 20px;
    font-size: 2.5em;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.1);
}

.game-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding: 15px;
    background: #f5f5f5;
    border-radius: 10px;
}

.current-player {
    font-size: 1.2em;
    font-weight: bold;
    display: flex;
    align-items: center;
    gap: 10px;
}

#currentPlayer {
    color: #667eea;
}

.ai-mode-badge {
    font-size: 0.8em;
    color: #666;
    font-weight: normal;
    font-style: italic;
}

.reset-btn {
    background: #667eea;
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1em;
    font-weight: bold;
    transition: all 0.3s;
}

.reset-btn:hover {
    background: #764ba2;
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

.reset-btn:active {
    transform: translateY(0);
}

.board {
    display: inline-grid;
    grid-template-columns: repeat(15, 1fr);
    gap: 0;
    background: #deb887;
    padding: 15px;
    border-radius: 10px;
    box-shadow: inset 0 0 20px rgba(0, 0, 0, 0.1);
    margin: 20px auto;
}

.cell {
    width: 30px;
    height: 30px;
    border: 1px solid #8b7355;
    background: #deb887;
    cursor: pointer;
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: background 0.2s;
}

.cell:hover {
    background: #d4a574;
}

.cell.black,
.cell.white {
    cursor: not-allowed;
}

.cell.black:hover,
.cell.white:hover {
    background: #deb887;
}

.stone-svg {
    width: 24px;
    height: 24px;
    position: absolute;
    pointer-events: none;
    animation: stonePlace 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.stone-svg.black-stone {
    filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.4));
}

.stone-svg.white-stone {
    filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.2));
}

@keyframes stonePlace {
    0% {
        transform: scale(0) rotate(-180deg);
        opacity: 0;
    }
    50% {
        transform: scale(1.2) rotate(0deg);
    }
    100% {
        transform: scale(1) rotate(0deg);
        opacity: 1;
    }
}

.stone-svg.winning {
    animation: winningPulse 1s ease-in-out infinite;
}

@keyframes winningPulse {
    0%, 100% {
        transform: scale(1);
        filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.4));
    }
    50% {
        transform: scale(1.15);
        filter: drop-shadow(0 4px 8px rgba(255, 215, 0, 0.8));
    }
}

.message {
    margin-top: 20px;
    font-size: 1.5em;
    font-weight: bold;
    min-height: 40px;
    color: #667eea;
}

.message.winner {
    color: #28a745;
    animation: pulse 1s infinite;
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
}

@media (max-width: 600px) {
    .cell {
        width: 20px;
        height: 20px;
    }
    
    .stone-svg {
        width: 16px;
        height: 16px;
    }
    
    h1 {
        font-size: 1.8em;
    }
    
    .game-info {
        flex-direction: column;
        gap: 10px;
    }
}