/* Puzzle Slide Kids - Mobile-first CSS */

/* CSS Reset & Variables */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    /* Colors - kid-friendly palette */
    --color-bg: #FFF9E3;
    --color-primary: #FF6B6B;
    --color-secondary: #4ECDC4;
    --color-accent: #FFE66D;
    --color-text: #2C3E50;
    --color-text-light: #7F8C8D;
    --color-success: #2ECC71;
    --color-white: #FFFFFF;

    /* Shadows */
    --shadow-soft: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-medium: 0 6px 12px rgba(0, 0, 0, 0.15);
    --shadow-hard: 0 8px 16px rgba(0, 0, 0, 0.2);

    /* Borders */
    --radius-small: 8px;
    --radius-medium: 12px;
    --radius-large: 16px;
    --radius-round: 50%;

    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;

    /* Spacing */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
}

/* Base */
html {
    font-size: 16px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    background: var(--color-bg);
    color: var(--color-text);
    min-height: 100vh;
    min-height: 100dvh;
    overflow-x: hidden;
}

/* Screen Management */
.screen {
    display: none;
    flex-direction: column;
    align-items: center;
    min-height: 100vh;
    min-height: 100dvh;
    padding: var(--spacing-md);
    padding-bottom: calc(var(--spacing-xl) + env(safe-area-inset-bottom));
}

.screen.active {
    display: flex;
}

/* ==================== HOME SCREEN ==================== */
.header {
    text-align: center;
    margin-bottom: var(--spacing-lg);
}

.header h1 {
    font-size: 2rem;
    color: var(--color-primary);
    margin-bottom: var(--spacing-xs);
}

.subtitle {
    font-size: 1rem;
    color: var(--color-text-light);
}

/* Image Selector */
.image-selector {
    width: 100%;
    max-width: 320px;
    margin-bottom: var(--spacing-lg);
}

.image-selector h2 {
    font-size: 1.1rem;
    text-align: center;
    margin-bottom: var(--spacing-md);
    color: var(--color-text);
}

.image-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-sm);
}

.image-option {
    aspect-ratio: 1;
    background: var(--color-white);
    border: 3px solid transparent;
    border-radius: var(--radius-medium);
    font-size: 2.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition-fast);
    box-shadow: var(--shadow-soft);
    -webkit-tap-highlight-color: transparent;
    touch-action: manipulation;
}

.image-option:hover,
.image-option:focus {
    transform: scale(1.05);
}

.image-option.selected {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-medium);
    transform: scale(1.05);
}

/* Difficulty Selector */
.difficulty-selector {
    width: 100%;
    max-width: 280px;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

/* Buttons */
.btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    min-height: 48px;
    padding: var(--spacing-md) var(--spacing-lg);
    border: none;
    border-radius: var(--radius-medium);
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition-fast);
    -webkit-tap-highlight-color: transparent;
    touch-action: manipulation;
}

.btn-large {
    min-height: 56px;
    font-size: 1.2rem;
}

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

.btn-primary:hover,
.btn-primary:active {
    background: #E55A5A;
    transform: translateY(-2px);
    box-shadow: var(--shadow-medium);
}

.btn-secondary {
    background: var(--color-secondary);
    color: var(--color-white);
    box-shadow: var(--shadow-soft);
}

.btn-secondary:hover,
.btn-secondary:active {
    background: #45B7AA;
    transform: translateY(-2px);
    box-shadow: var(--shadow-medium);
}

.btn-icon-only {
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-white);
    border: none;
    border-radius: var(--radius-round);
    font-size: 1.5rem;
    cursor: pointer;
    box-shadow: var(--shadow-soft);
    -webkit-tap-highlight-color: transparent;
    touch-action: manipulation;
}

.btn-icon-only:active {
    transform: scale(0.95);
}

/* Records */
.records {
    text-align: center;
    color: var(--color-text-light);
    font-size: 0.9rem;
}

.records p {
    margin-bottom: var(--spacing-xs);
}

/* ==================== PREVIEW SCREEN ==================== */
.game-header {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-lg);
}

.game-header h2 {
    font-size: 1.2rem;
    color: var(--color-text);
}

.spacer {
    width: 44px;
}

.preview-container {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-lg);
}

.preview-image {
    width: min(280px, 80vw);
    aspect-ratio: 1;
    background: var(--color-white);
    border-radius: var(--radius-large);
    box-shadow: var(--shadow-medium);
    display: grid;
    overflow: hidden;
}

.preview-image.grid-2x2 {
    grid-template-columns: repeat(2, 1fr);
}

.preview-image.grid-3x3 {
    grid-template-columns: repeat(3, 1fr);
}

.preview-tile {
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 3rem;
    background: var(--color-white);
    border: 1px solid rgba(0, 0, 0, 0.05);
}

.preview-hint {
    margin-top: var(--spacing-md);
    color: var(--color-text-light);
    font-size: 0.9rem;
}

/* ==================== GAME SCREEN ==================== */
.stats {
    display: flex;
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-lg);
}

.stat {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.stat-label {
    font-size: 0.8rem;
    color: var(--color-text-light);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.stat-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-text);
}

/* Puzzle Board */
.puzzle-container {
    position: relative;
    margin-bottom: var(--spacing-lg);
}

.puzzle-board {
    width: min(300px, 85vw);
    aspect-ratio: 1;
    display: grid;
    gap: 4px;
    background: var(--color-text);
    padding: 4px;
    border-radius: var(--radius-large);
    box-shadow: var(--shadow-hard);
}

.puzzle-board.grid-2x2 {
    grid-template-columns: repeat(2, 1fr);
}

.puzzle-board.grid-3x3 {
    grid-template-columns: repeat(3, 1fr);
}

/* Puzzle Tiles */
.puzzle-tile {
    background: var(--color-white);
    border-radius: var(--radius-small);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    cursor: pointer;
    transition: transform var(--transition-fast);
    -webkit-tap-highlight-color: transparent;
    touch-action: manipulation;
    user-select: none;
}

.puzzle-board.grid-2x2 .puzzle-tile {
    font-size: 4rem;
}

.puzzle-tile:active:not(.empty) {
    transform: scale(0.95);
}

.puzzle-tile.empty {
    background: transparent;
    cursor: default;
}

.puzzle-tile.moving {
    z-index: 10;
    transition: transform var(--transition-normal);
}

/* Hint Overlay */
.hint-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.8);
    border-radius: var(--radius-large);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition-fast);
}

.hint-overlay.visible {
    opacity: 1;
    visibility: visible;
}

.hint-image {
    width: 90%;
    aspect-ratio: 1;
    display: grid;
    gap: 2px;
    background: var(--color-white);
    padding: 2px;
    border-radius: var(--radius-medium);
}

.hint-image.grid-2x2 {
    grid-template-columns: repeat(2, 1fr);
}

.hint-image.grid-3x3 {
    grid-template-columns: repeat(3, 1fr);
}

.hint-tile {
    background: var(--color-white);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
}

/* ==================== WIN SCREEN ==================== */
#screen-win {
    background: linear-gradient(135deg, #FFE66D 0%, #FF6B6B 50%, #4ECDC4 100%);
    position: relative;
    overflow: hidden;
}

.win-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    flex: 1;
    z-index: 1;
}

.win-title {
    font-size: 2.2rem;
    color: var(--color-white);
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
    margin-bottom: var(--spacing-md);
}

.stars {
    font-size: 3rem;
    margin-bottom: var(--spacing-lg);
    animation: pulse 1s ease-in-out infinite;
}

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

.win-stats {
    display: flex;
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-lg);
}

.win-stat {
    display: flex;
    flex-direction: column;
    align-items: center;
    background: rgba(255, 255, 255, 0.9);
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-medium);
}

.win-stat-label {
    font-size: 0.8rem;
    color: var(--color-text-light);
    text-transform: uppercase;
}

.win-stat-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-text);
}

.new-record {
    font-size: 1.2rem;
    color: var(--color-white);
    background: var(--color-success);
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-large);
    margin-bottom: var(--spacing-lg);
    animation: bounce 0.5s ease-in-out infinite alternate;
}

@keyframes bounce {
    from { transform: translateY(0); }
    to { transform: translateY(-5px); }
}

.win-buttons {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    width: 100%;
    max-width: 280px;
}

/* Confetti */
.confetti {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    pointer-events: none;
    overflow: hidden;
}

.confetti-piece {
    position: absolute;
    width: 10px;
    height: 10px;
    animation: confetti-fall 3s ease-in-out forwards;
}

@keyframes confetti-fall {
    0% {
        transform: translateY(-100%) rotate(0deg);
        opacity: 1;
    }
    100% {
        transform: translateY(100vh) rotate(720deg);
        opacity: 0;
    }
}

/* ==================== RESPONSIVE ==================== */
@media (min-width: 768px) {
    .header h1 {
        font-size: 2.5rem;
    }

    .image-grid {
        gap: var(--spacing-md);
    }

    .image-option {
        font-size: 3rem;
    }

    .puzzle-board {
        width: 400px;
    }

    .puzzle-tile {
        font-size: 3.5rem;
    }

    .puzzle-board.grid-2x2 .puzzle-tile {
        font-size: 5rem;
    }

    .preview-image {
        width: 350px;
    }

    .preview-tile {
        font-size: 4rem;
    }
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
    :root {
        --color-bg: #1A1A2E;
        --color-text: #EAEAEA;
        --color-text-light: #A0A0A0;
    }

    .image-option,
    .puzzle-tile:not(.empty),
    .preview-tile,
    .hint-tile,
    .win-stat {
        background: #2A2A4E;
    }

    .btn-icon-only {
        background: #2A2A4E;
        color: var(--color-text);
    }
}

/* Reduce motion for accessibility */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}