@import url('https://fonts.googleapis.com/css2?family=Outfit:wght@400;600;700&display=swap');

:root {
    --xo-cell-size: 100px;
    --xo-board-gap: 10px;
    --xo-x-color: #2563eb;
    --xo-x-glow: rgba(37, 99, 235, 0.35);
    --xo-o-color: #dc2626;
    --xo-o-glow: rgba(220, 38, 38, 0.35);
    --xo-bg: linear-gradient(160deg, #0f172a 0%, #1e293b 50%, #0f172a 100%);
    --xo-card-bg: rgba(30, 41, 59, 0.95);
    --xo-card-border: rgba(71, 85, 105, 0.5);
    --xo-cell-bg: rgba(30, 41, 59, 0.8);
    --xo-cell-border: rgba(71, 85, 105, 0.6);
    --xo-cell-hover: rgba(51, 65, 85, 0.9);
    --xo-text: #f1f5f9;
    --xo-text-muted: #94a3b8;
    --xo-accent: #38bdf8;
    --xo-radius: 16px;
    --xo-radius-sm: 10px;
    --shadow-lg: 0 25px 50px -12px rgba(0, 0, 0, 0.4);
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

* {
    box-sizing: border-box;
}

body {
    font-family: 'Outfit', sans-serif;
    background: var(--xo-bg);
    background-attachment: fixed;
    min-height: 100vh;
    color: var(--xo-text);
    margin: 0;
}

/* Centered, fixed width so board and card fit on all screens */
.container {
    max-width: 420px;
    margin-left: auto;
    margin-right: auto;
}

/* Desktop: slightly larger game area for a balanced look */
@media (min-width: 992px) {
    .container {
        max-width: 460px;
    }
    :root {
        --xo-cell-size: 110px;
    }
    .xo-cell {
        font-size: 2.75rem;
    }
}

/* Header */
header h1 {
    font-weight: 700;
    letter-spacing: -0.02em;
    background: linear-gradient(135deg, #fff 0%, #94a3b8 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

header .lead {
    color: var(--xo-text-muted);
    font-weight: 400;
}

/* Cards with entrance animation */
.xo-view {
    opacity: 0;
    transform: translateY(12px);
    transition: opacity var(--transition), transform var(--transition);
}

.xo-view.visible {
    opacity: 1;
    transform: translateY(0);
}

.card {
    border: 1px solid var(--xo-card-border);
    border-radius: var(--xo-radius);
    background: var(--xo-card-bg);
    backdrop-filter: blur(12px);
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

.card-title {
    color: var(--xo-text);
    font-weight: 600;
}

.form-label {
    color: var(--xo-text-muted);
    font-weight: 500;
}

.form-control,
.form-select {
    background: rgba(15, 23, 42, 0.6);
    border: 1px solid var(--xo-cell-border);
    color: var(--xo-text);
    border-radius: var(--xo-radius-sm);
    transition: border-color 0.2s, box-shadow 0.2s;
}

.form-control:focus,
.form-select:focus {
    background: rgba(15, 23, 42, 0.8);
    border-color: var(--xo-accent);
    box-shadow: 0 0 0 3px rgba(56, 189, 248, 0.2);
    color: var(--xo-text);
}

.form-control::placeholder {
    color: var(--xo-text-muted);
}

.form-check-input:checked {
    background-color: var(--xo-accent);
    border-color: var(--xo-accent);
}

.form-check-label {
    color: var(--xo-text-muted);
}

/* Buttons */
.btn-primary {
    background: linear-gradient(135deg, #2563eb 0%, #1d4ed8 100%);
    border: none;
    border-radius: var(--xo-radius-sm);
    font-weight: 600;
    padding: 0.75rem 1.25rem;
    transition: transform 0.2s, box-shadow 0.2s;
}

.btn-primary:hover {
    transform: translateY(-1px);
    box-shadow: 0 8px 20px rgba(37, 99, 235, 0.4);
}

.btn-outline-secondary {
    border-color: var(--xo-cell-border);
    color: var(--xo-text-muted);
    border-radius: var(--xo-radius-sm);
}

.btn-outline-secondary:hover {
    background: var(--xo-cell-hover);
    border-color: var(--xo-text-muted);
    color: var(--xo-text);
}

/* Board */
.xo-board {
    display: grid;
    grid-template-columns: repeat(3, var(--xo-cell-size));
    grid-template-rows: repeat(3, var(--xo-cell-size));
    gap: var(--xo-board-gap);
    margin: 0 auto;
    width: fit-content;
    background: var(--xo-cell-border);
    padding: var(--xo-board-gap);
    border-radius: var(--xo-radius);
    box-shadow: inset 0 2px 8px rgba(0, 0, 0, 0.3);
}

.xo-cell {
    width: var(--xo-cell-size);
    height: var(--xo-cell-size);
    background: var(--xo-cell-bg);
    border: 2px solid var(--xo-cell-border);
    border-radius: var(--xo-radius-sm);
    font-size: 2.5rem;
    font-weight: 700;
    font-family: 'Outfit', sans-serif;
    cursor: pointer;
    transition: background 0.2s, transform 0.15s, border-color 0.2s, box-shadow 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 1;
    transform: scale(1);
}

.xo-cell.animate-in {
    animation: cellPop 0.35s cubic-bezier(0.34, 1.56, 0.64, 1) forwards;
}

.xo-cell.symbol-enter {
    animation: symbolDraw 0.4s cubic-bezier(0.34, 1.56, 0.64, 1) forwards;
}

.xo-cell:hover:not(:disabled) {
    background: var(--xo-cell-hover);
    transform: scale(1.04);
    border-color: var(--xo-accent);
    box-shadow: 0 0 20px rgba(56, 189, 248, 0.15);
}

.xo-cell:disabled {
    cursor: default;
}

.xo-cell.x {
    color: var(--xo-x-color);
    text-shadow: 0 0 20px var(--xo-x-glow);
}

.xo-cell.o {
    color: var(--xo-o-color);
    text-shadow: 0 0 20px var(--xo-o-glow);
}

.xo-cell.win-cell {
    animation: winPulse 0.6s ease-out 2;
    box-shadow: 0 0 24px rgba(56, 189, 248, 0.4);
}

@keyframes cellPop {
    from {
        opacity: 0;
        transform: scale(0.6);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

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

@keyframes winPulse {
    0%, 100% {
        box-shadow: 0 0 24px rgba(56, 189, 248, 0.4);
    }
    50% {
        box-shadow: 0 0 32px rgba(56, 189, 248, 0.7);
    }
}

/* Status badge */
#game-status {
    font-weight: 600;
    padding: 0.5rem 0.75rem;
    border-radius: var(--xo-radius-sm);
    transition: opacity 0.3s;
}

#game-status.thinking {
    animation: thinkingPulse 1s ease-in-out infinite;
}

@keyframes thinkingPulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.6;
    }
}

/* History list */
.list-group-item {
    cursor: pointer;
    background: rgba(30, 41, 59, 0.5);
    border-color: var(--xo-cell-border);
    color: var(--xo-text);
    border-radius: var(--xo-radius-sm) !important;
    margin-bottom: 6px;
    opacity: 0;
    transform: translateX(-8px);
    transition: background 0.2s, transform 0.2s;
}

.list-group-item.animate-in {
    animation: listItemIn 0.35s ease-out forwards;
}

.list-group-item:hover {
    background: var(--xo-cell-hover);
    transform: translateX(4px);
}

@keyframes listItemIn {
    from {
        opacity: 0;
        transform: translateX(-8px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

/* Modal */
.modal-content {
    background: var(--xo-card-bg);
    border: 1px solid var(--xo-card-border);
    border-radius: var(--xo-radius);
    color: var(--xo-text);
}

.modal-header {
    border-color: var(--xo-cell-border);
}

.modal-footer {
    border-color: var(--xo-cell-border);
}

.modal-title {
    color: var(--xo-text);
}

.btn-close {
    filter: invert(1);
    opacity: 0.7;
}

#result-message {
    color: var(--xo-text);
    font-weight: 600;
}

/* Responsive */
@media (max-width: 400px) {
    :root {
        --xo-cell-size: 82px;
    }
    .xo-cell {
        font-size: 2rem;
    }
}

/* View transition overlay (for crossfade) */
.xo-overlay {
    position: fixed;
    inset: 0;
    pointer-events: none;
    z-index: 1000;
    opacity: 0;
    transition: opacity 0.2s ease;
}

.xo-overlay.active {
    opacity: 1;
}