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

:root {
    --bg-gradient-start: #0f0c29;
    --bg-gradient-end: #302b63;
    --text-primary: #e0e0e0;
    --text-secondary: #bb86fc;
    --card-bg: rgba(30, 30, 30, 0.95);
    --cell-bg: #1e1e1e;
    --cell-hover: #2a2a2a;
    --board-bg: rgba(0, 0, 0, 0.3);
    --shadow-color: rgba(0, 0, 0, 0.5);
    --shadow-hover: rgba(0, 0, 0, 0.7);
    --btn-primary-start: #bb86fc;
    --btn-primary-end: #6200ea;
    --player-x-color: #ff6b9d;
    --player-o-color: #4fc3f7;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: linear-gradient(135deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
    padding: 20px;
    transition: background 0.5s ease;
}

.container {
    text-align: center;
    max-width: 600px;
    width: 100%;
}

h1 {
    color: var(--text-primary);
    font-size: clamp(2rem, 5vw, 3rem);
    margin-bottom: 30px;
    text-shadow: 2px 2px 4px var(--shadow-color);
    animation: fadeInDown 0.6s ease-out;
}

.mode-selection {
    display: flex;
    gap: 15px;
    justify-content: center;
    margin-bottom: 30px;
    flex-wrap: wrap;
    animation: fadeIn 0.8s ease-out;
}

.mode-btn {
    padding: 15px 30px;
    font-size: clamp(0.9rem, 2vw, 1.1rem);
    border: none;
    border-radius: 12px;
    cursor: pointer;
    background: var(--cell-bg);
    color: var(--text-secondary);
    font-weight: bold;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px var(--shadow-color);
}

.mode-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px var(--shadow-hover);
}

.mode-btn.active {
    background: linear-gradient(135deg, var(--btn-primary-start) 0%, var(--btn-primary-end) 100%);
    color: white;
}

.game-info {
    background: var(--card-bg);
    padding: 20px;
    border-radius: 15px;
    margin-bottom: 25px;
    box-shadow: 0 8px 32px var(--shadow-color);
    animation: fadeIn 1s ease-out;
    transition: background 0.3s ease;
}

.current-player {
    font-size: clamp(1.1rem, 2.5vw, 1.3rem);
    color: var(--text-secondary);
    font-weight: bold;
    margin-bottom: 10px;
}

.score-board {
    display: flex;
    justify-content: space-around;
    margin-top: 15px;
    flex-wrap: wrap;
    gap: 10px;
}

.score {
    font-size: clamp(0.9rem, 2vw, 1rem);
    color: #aaa;
}

.score span {
    font-weight: bold;
    color: var(--text-secondary);
}

.board {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 15px;
    max-width: 450px;
    width: 100%;
    margin: 0 auto 30px;
    padding: 20px;
    background: var(--board-bg);
    border-radius: 20px;
    backdrop-filter: blur(10px);
    animation: scaleIn 0.5s ease-out;
    transition: background 0.3s ease;
}

.cell {
    aspect-ratio: 1;
    background: var(--cell-bg);
    border: none;
    border-radius: 15px;
    font-size: clamp(2rem, 8vw, 3.5rem);
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px var(--shadow-color);
    display: flex;
    align-items: center;
    justify-content: center;
}

.cell:hover:not(.taken) {
    background: var(--cell-hover);
    transform: scale(1.05);
}

.cell.taken {
    cursor: not-allowed;
}

.cell.x {
    color: var(--player-x-color);
    animation: popIn 0.3s ease-out;
}

.cell.o {
    color: var(--player-o-color);
    animation: popIn 0.3s ease-out;
}

.cell.winning {
    animation: winPulse 0.6s ease-in-out infinite;
    background: linear-gradient(135deg, var(--btn-primary-start) 0%, var(--btn-primary-end) 100%);
    color: white;
}

.controls {
    display: flex;
    gap: 15px;
    justify-content: center;
    flex-wrap: wrap;
    animation: fadeIn 1.2s ease-out;
}

.btn {
    padding: 15px 35px;
    font-size: clamp(0.9rem, 2vw, 1.1rem);
    border: none;
    border-radius: 12px;
    cursor: pointer;
    font-weight: bold;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px var(--shadow-color);
}

.reset-btn {
    background: linear-gradient(135deg, var(--btn-primary-start) 0%, var(--btn-primary-end) 100%);
    color: white;
}

.reset-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px var(--shadow-hover);
}

.reset-score-btn {
    background: var(--cell-bg);
    color: var(--text-secondary);
}

.reset-score-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px var(--shadow-hover);
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes scaleIn {
    from {
        opacity: 0;
        transform: scale(0.8);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

@keyframes popIn {
    0% {
        transform: scale(0);
    }
    50% {
        transform: scale(1.2);
    }
    100% {
        transform: scale(1);
    }
}

@keyframes winPulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.1);
    }
}

@media (max-width: 480px) {
    .board {
        gap: 10px;
        padding: 15px;
    }
}