/* CSS Reset and Variables */
:root {
    /* Color Palette - Clean & Minimal */
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary-color: #64748b;
    --secondary-hover: #475569;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --danger-color: #ef4444;
    
    /* Neutral Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f1f5f9;
    --text-primary: #0f172a;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    
    /* Game Colors */
    --player-x: #ef4444;
    --player-o: #3b82f6;
    --cell-bg: #ffffff;
    --cell-border: #e2e8f0;
    --cell-hover: #f8fafc;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;
}

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

body {
    font-family: var(--font-family);
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-tertiary) 100%);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-md);
}

/* Container */
.container {
    width: 100%;
    max-width: 500px;
    background: var(--bg-primary);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    padding: var(--spacing-2xl);
    position: relative;
    overflow: hidden;
}

.container::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--player-x) 0%, var(--player-o) 100%);
}

/* Header */
.game-header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.game-title {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
}

.title-icon {
    width: 2rem;
    height: 2rem;
    color: var(--primary-color);
}

.game-subtitle {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* Game Info */
.game-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-xl);
    padding: var(--spacing-md);
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    border: 1px solid var(--cell-border);
}

.current-player {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.player-label {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    font-weight: 500;
}

.player-indicator {
    font-size: var(--font-size-xl);
    font-weight: 700;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    background: var(--bg-primary);
    border: 2px solid;
    min-width: 2.5rem;
    text-align: center;
    transition: var(--transition-normal);
}

.player-indicator.player-x {
    color: var(--player-x);
    border-color: var(--player-x);
    background: rgba(239, 68, 68, 0.1);
}

.player-indicator.player-o {
    color: var(--player-o);
    border-color: var(--player-o);
    background: rgba(59, 130, 246, 0.1);
}

.score-board {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.score-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xs);
}

.score-label {
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--text-secondary);
}

.score-value {
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--text-primary);
}

.score-divider {
    font-size: var(--font-size-lg);
    color: var(--text-muted);
    font-weight: 300;
}

/* Game Board */
.game-board {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-xl);
    padding: var(--spacing-md);
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    border: 1px solid var(--cell-border);
}

.cell {
    aspect-ratio: 1;
    background: var(--cell-bg);
    border: 2px solid var(--cell-border);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-4xl);
    font-weight: 700;
    cursor: pointer;
    transition: var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.cell::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--cell-hover);
    opacity: 0;
    transition: var(--transition-fast);
}

.cell:hover::before {
    opacity: 1;
}

.cell:hover {
    border-color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.cell.disabled {
    cursor: not-allowed;
    opacity: 0.6;
}

.cell.disabled:hover {
    transform: none;
    box-shadow: none;
    border-color: var(--cell-border);
}

.cell.disabled::before {
    display: none;
}

.cell.player-x {
    color: var(--player-x);
    border-color: var(--player-x);
    background: rgba(239, 68, 68, 0.05);
}

.cell.player-o {
    color: var(--player-o);
    border-color: var(--player-o);
    background: rgba(59, 130, 246, 0.05);
}

.cell.winning {
    animation: winningCell 0.6s ease-in-out;
    background: linear-gradient(135deg, var(--success-color), #059669);
    color: white;
    border-color: var(--success-color);
}

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

/* Game Controls */
.game-controls {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
}

.btn {
    flex: 1;
    padding: var(--spacing-md) var(--spacing-lg);
    border: none;
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition-normal);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: var(--transition-normal);
}

.btn:hover::before {
    left: 100%;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--cell-border);
}

.btn-secondary:hover {
    background: var(--secondary-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

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

.btn i {
    width: 1rem;
    height: 1rem;
}

/* Game Status */
.game-status {
    text-align: center;
}

.status-text {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    font-weight: 500;
}

/* Modal */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(4px);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition-normal);
    z-index: 1000;
    padding: var(--spacing-md);
}

.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}

.modal {
    background: var(--bg-primary);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    max-width: 400px;
    width: 100%;
    transform: scale(0.9) translateY(20px);
    transition: var(--transition-normal);
}

.modal-overlay.active .modal {
    transform: scale(1) translateY(0);
}

.modal-content {
    padding: var(--spacing-2xl);
    text-align: center;
}

.modal-icon {
    width: 4rem;
    height: 4rem;
    margin: 0 auto var(--spacing-lg);
    background: var(--success-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
}

.modal-icon i {
    width: 2rem;
    height: 2rem;
}

.modal-icon.tie {
    background: var(--warning-color);
}

.modal-title {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.modal-message {
    font-size: var(--font-size-base);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
}

.modal-actions {
    display: flex;
    gap: var(--spacing-md);
}

/* Responsive Design */
@media (max-width: 480px) {
    .container {
        padding: var(--spacing-lg);
        margin: var(--spacing-sm);
    }
    
    .game-title {
        font-size: var(--font-size-2xl);
    }
    
    .game-info {
        flex-direction: column;
        gap: var(--spacing-md);
        text-align: center;
    }
    
    .cell {
        font-size: var(--font-size-3xl);
    }
    
    .game-controls {
        flex-direction: column;
    }
    
    .modal-actions {
        flex-direction: column;
    }
}

/* Print Styles */
@media print {
    body {
        background: white;
    }
    
    .container {
        box-shadow: none;
        border: 1px solid #ccc;
    }
    
    .modal-overlay {
        display: none;
    }
    
    @page {
        margin: 1in;
        @top-center {
            content: "Tic Tac Toe Game";
        }
        @bottom-center {
            content: "Created by Helium";
        }
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus States */
.cell:focus,
.btn:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* High Contrast Mode */
@media (prefers-contrast: high) {
    :root {
        --cell-border: #000000;
        --text-secondary: #000000;
    }
}