:root {
    --bg-color: #0f172a;
    --card-bg: rgba(30, 41, 59, 0.7);
    --border-color: rgba(255, 255, 255, 0.1);
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --player-x: #38bdf8;
    --player-o: #f472b6;
    --win-line: #fbbf24;
    --cell-hover: rgba(255, 255, 255, 0.05);
    --gradient-x: linear-gradient(135deg, #38bdf8, #818cf8);
    --gradient-o: linear-gradient(135deg, #f472b6, #fb7185);
}

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

body {
    font-family: 'Outfit', sans-serif;
    background-color: var(--bg-color);
    background-image: 
        radial-gradient(at 0% 0%, rgba(56, 189, 248, 0.1) 0px, transparent 50%),
        radial-gradient(at 100% 100%, rgba(244, 114, 182, 0.1) 0px, transparent 50%);
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.game-container {
    background: var(--card-bg);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border: 1px solid var(--border-color);
    padding: 2.5rem;
    border-radius: 2rem;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    text-align: center;
    max-width: 90vw;
    z-index: 10;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
    background: linear-gradient(to right, #f8fafc, #94a3b8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.status-display {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    min-height: 1.5em;
    font-weight: 400;
}

.player-x {
    color: var(--player-x);
    font-weight: 600;
}

.player-o {
    color: var(--player-o);
    font-weight: 600;
}

.game-board {
    display: grid;
    grid-template-columns: repeat(3, 100px);
    grid-template-rows: repeat(3, 100px);
    gap: 12px;
    margin-bottom: 2rem;
    justify-content: center;
}

.cell {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    font-weight: 800;
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    user-select: none;
}

.cell:hover {
    background: var(--cell-hover);
    transform: translateY(-2px);
    border-color: rgba(255, 255, 255, 0.2);
}

.cell.taken {
    cursor: not-allowed;
    transform: none;
}

/* X Marker Style */
.cell.x::after {
    content: "X";
    background: var(--gradient-x);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: marker-pop 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

/* O Marker Style */
.cell.o::after {
    content: "O";
    background: var(--gradient-o);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: marker-pop 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

@keyframes marker-pop {
    from {
        opacity: 0;
        transform: scale(0.5);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.cell.winner {
    background: rgba(251, 191, 36, 0.1);
    border-color: var(--win-line);
    box-shadow: 0 0 20px rgba(251, 191, 36, 0.2);
}

.restart-btn {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 0.75rem 2rem;
    border-radius: 0.75rem;
    font-family: inherit;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.restart-btn:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.3);
    transform: scale(1.05);
}

/* Modal Overlay */
.overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(8px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 100;
    opacity: 1;
    transition: opacity 0.3s;
}

.overlay.hidden {
    opacity: 0;
    pointer-events: none;
}

.overlay-content {
    background: var(--card-bg);
    padding: 3rem;
    border-radius: 2rem;
    border: 1px solid var(--border-color);
    text-align: center;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
}

.overlay-content h2 {
    font-size: 3rem;
    margin-bottom: 2rem;
    font-weight: 800;
}

/* Responsive adjustments */
@media (max-width: 480px) {
    .game-board {
        grid-template-columns: repeat(3, 80px);
        grid-template-rows: repeat(3, 80px);
        gap: 8px;
    }
    
    .cell {
        font-size: 2rem;
        border-radius: 8px;
    }

    .game-container {
        padding: 1.5rem;
    }

    header h1 {
        font-size: 2rem;
    }
}