/* ==================== Material Expressive Design Tokens ==================== */
:root {
    /* Material 3 Color Palette - Light Theme */
    --md-sys-color-primary: #6750A4;
    --md-sys-color-on-primary: #FFFFFF;
    --md-sys-color-primary-container: #EADDFF;
    --md-sys-color-on-primary-container: #21005D;
    --md-sys-color-secondary: #625B71;
    --md-sys-color-on-secondary: #FFFFFF;
    --md-sys-color-secondary-container: #E8DEF8;
    --md-sys-color-on-secondary-container: #1D192B;
    --md-sys-color-tertiary: #7D5260;
    --md-sys-color-on-tertiary: #FFFFFF;
    --md-sys-color-tertiary-container: #FFD8E4;
    --md-sys-color-on-tertiary-container: #31111D;
    --md-sys-color-error: #B3261E;
    --md-sys-color-on-error: #FFFFFF;
    --md-sys-color-error-container: #F9DEDC;
    --md-sys-color-on-error-container: #410E0B;
    --md-sys-color-background: #FFFBFE;
    --md-sys-color-on-background: #1C1B1F;
    --md-sys-color-surface: #FFFBFE;
    --md-sys-color-on-surface: #1C1B1F;
    --md-sys-color-surface-variant: #E7E0EC;
    --md-sys-color-on-surface-variant: #49454F;
    --md-sys-color-outline: #79747E;
    --md-sys-color-outline-variant: #CAC4D0;
    
    /* Material 3 Elevation */
    --md-sys-elevation-1: 0 1px 2px rgba(0,0,0,0.3), 0 1px 3px 1px rgba(0,0,0,0.15);
    --md-sys-elevation-2: 0 1px 2px rgba(0,0,0,0.3), 0 2px 6px 2px rgba(0,0,0,0.15);
    --md-sys-elevation-3: 0 1px 3px rgba(0,0,0,0.3), 0 4px 8px 3px rgba(0,0,0,0.15);
    --md-sys-elevation-4: 0 2px 3px rgba(0,0,0,0.3), 0 6px 10px 4px rgba(0,0,0,0.15);
    --md-sys-elevation-5: 0 4px 4px rgba(0,0,0,0.3), 0 8px 12px 6px rgba(0,0,0,0.15);
    
    /* Material 3 Shape */
    --md-sys-shape-corner-small: 8px;
    --md-sys-shape-corner-medium: 12px;
    --md-sys-shape-corner-large: 16px;
    --md-sys-shape-corner-extra-large: 24px;
    --md-sys-shape-corner-full: 9999px;
    
    /* Material 3 Motion */
    --md-sys-motion-duration-short: 200ms;
    --md-sys-motion-duration-medium: 400ms;
    --md-sys-motion-duration-long: 600ms;
    --md-sys-motion-easing-standard: cubic-bezier(0.2, 0, 0, 1);
    --md-sys-motion-easing-emphasized: cubic-bezier(0.2, 0, 0, 1);
    --md-sys-motion-easing-decelerate: cubic-bezier(0, 0, 0.2, 1);
    
    /* Material 3 Typography */
    --md-sys-typescale-display-large: 400 57px/64px 'Roboto', sans-serif;
    --md-sys-typescale-display-medium: 400 45px/52px 'Roboto', sans-serif;
    --md-sys-typescale-display-small: 400 36px/44px 'Roboto', sans-serif;
    --md-sys-typescale-headline-large: 400 32px/40px 'Roboto', sans-serif;
    --md-sys-typescale-headline-medium: 400 28px/36px 'Roboto', sans-serif;
    --md-sys-typescale-headline-small: 400 24px/32px 'Roboto', sans-serif;
    --md-sys-typescale-title-large: 400 22px/28px 'Roboto', sans-serif;
    --md-sys-typescale-title-medium: 500 16px/24px 'Roboto', sans-serif;
    --md-sys-typescale-title-small: 500 14px/20px 'Roboto', sans-serif;
    --md-sys-typescale-body-large: 400 16px/24px 'Roboto', sans-serif;
    --md-sys-typescale-body-medium: 400 14px/20px 'Roboto', sans-serif;
    --md-sys-typescale-body-small: 400 12px/16px 'Roboto', sans-serif;
    --md-sys-typescale-label-large: 500 14px/20px 'Roboto', sans-serif;
    --md-sys-typescale-label-medium: 500 12px/16px 'Roboto', sans-serif;
    --md-sys-typescale-label-small: 500 11px/16px 'Roboto', sans-serif;
}

/* Dark Theme Tokens */
body.dark {
    --md-sys-color-primary: #D0BCFF;
    --md-sys-color-on-primary: #381E72;
    --md-sys-color-primary-container: #4F378B;
    --md-sys-color-on-primary-container: #EADDFF;
    --md-sys-color-secondary: #CCC2DC;
    --md-sys-color-on-secondary: #332D41;
    --md-sys-color-secondary-container: #4A4458;
    --md-sys-color-on-secondary-container: #E8DEF8;
    --md-sys-color-tertiary: #EFB8C8;
    --md-sys-color-on-tertiary: #492532;
    --md-sys-color-tertiary-container: #633B48;
    --md-sys-color-on-tertiary-container: #FFD8E4;
    --md-sys-color-error: #F2B8B5;
    --md-sys-color-on-error: #601410;
    --md-sys-color-error-container: #8C1D18;
    --md-sys-color-on-error-container: #F9DEDC;
    --md-sys-color-background: #1C1B1F;
    --md-sys-color-on-background: #E6E1E5;
    --md-sys-color-surface: #1C1B1F;
    --md-sys-color-on-surface: #E6E1E5;
    --md-sys-color-surface-variant: #49454F;
    --md-sys-color-on-surface-variant: #CAC4D0;
    --md-sys-color-outline: #938F99;
    --md-sys-color-outline-variant: #49454F;
}

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

body {
    font-family: 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    background: var(--md-sys-color-background);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    color: var(--md-sys-color-on-background);
    touch-action: manipulation;
    transition: background var(--md-sys-motion-duration-medium) var(--md-sys-motion-easing-standard),
                color var(--md-sys-motion-duration-medium) var(--md-sys-motion-easing-standard);
}

body.dark .game-container {
    background: transparent;
}

body.dark #game {
    background: var(--md-sys-color-surface-variant);
}

body.dark .score-box {
    background: var(--md-sys-color-surface-variant);
}

body.dark #instructions {
    background: var(--md-sys-color-surface-variant);
}

body.dark .tutorial-content,
body.dark .settings-content,
body.dark .stats-content {
    background: var(--md-sys-color-surface);
}

body.dark .tutorial-tips,
body.dark .settings-section,
body.dark .stats-grid {
    background: var(--md-sys-color-surface-variant);
}

/* Reduced Motion */
body.reduced-motion *,
body.reduced-motion *::before,
body.reduced-motion *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
}

/* Paused State */
body.paused::after {
    content: '⏸️ PAUSED';
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 48px;
    font-weight: bold;
    color: var(--md-sys-color-on-surface);
    text-shadow: 0 0 20px rgba(0, 0, 0, 0.3);
    z-index: 1000;
    pointer-events: none;
}

.game-container {
    text-align: center;
    width: 100%;
    max-width: 500px;
    padding: 24px 16px;
    box-sizing: border-box;
    transition: background var(--md-sys-motion-duration-medium) var(--md-sys-motion-easing-standard);
}

h1 {
    font: var(--md-sys-typescale-display-large);
    margin: 0 0 16px 0;
    color: var(--md-sys-color-primary);
    letter-spacing: -0.5px;
}

.header-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 16px;
    flex-wrap: wrap;
    gap: 12px;
}

.score-container {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
    justify-content: center;
    width: 100%;
}

.score-box {
    background: var(--md-sys-color-surface-variant);
    color: var(--md-sys-color-on-surface);
    padding: 12px 16px;
    border-radius: var(--md-sys-shape-corner-medium);
    min-width: 80px;
    flex: 1;
    max-width: 100px;
    box-shadow: var(--md-sys-elevation-1);
    transition: box-shadow var(--md-sys-motion-duration-short) var(--md-sys-motion-easing-standard);
}

.score-box:hover {
    box-shadow: var(--md-sys-elevation-2);
}

.score-label {
    font: var(--md-sys-typescale-label-large);
    color: var(--md-sys-color-on-surface-variant);
    margin-bottom: 4px;
}

#score, #best, #moves, #timer {
    font: var(--md-sys-typescale-headline-medium);
    color: var(--md-sys-color-on-surface);
}

#score {
    color: var(--md-sys-color-primary);
}

.controls-row {
    display: flex;
    gap: 8px;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 16px;
}

.btn {
    background: var(--md-sys-color-secondary-container);
    color: var(--md-sys-color-on-secondary-container);
    border: none;
    padding: 10px 20px;
    font: var(--md-sys-typescale-label-large);
    border-radius: var(--md-sys-shape-corner-full);
    cursor: pointer;
    transition: all var(--md-sys-motion-duration-short) var(--md-sys-motion-easing-standard);
    display: inline-flex;
    align-items: center;
    gap: 8px;
    box-shadow: var(--md-sys-elevation-1);
}

.btn:hover:not(:disabled) {
    background: var(--md-sys-color-primary-container);
    color: var(--md-sys-color-on-primary-container);
    box-shadow: var(--md-sys-elevation-2);
}

.btn:active:not(:disabled) {
    transform: scale(0.98);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-secondary {
    background: transparent;
    border: 1px solid var(--md-sys-color-outline);
}

.btn-install {
    background: var(--md-sys-color-primary);
    color: var(--md-sys-color-on-primary);
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%, 100% { box-shadow: 0 0 0 0 rgba(103, 80, 164, 0.4); }
    50% { box-shadow: 0 0 0 10px rgba(103, 80, 164, 0); }
}

/* Focus indicators for accessibility */
.btn:focus-visible,
.restart-btn:focus-visible {
    outline: 2px solid var(--md-sys-color-primary);
    outline-offset: 2px;
}

#game {
    width: 456px;
    height: 456px;
    max-width: 90vw;
    max-height: 90vw;
    background: var(--md-sys-color-surface-variant);
    border-radius: var(--md-sys-shape-corner-large);
    padding: 4px;
    margin: 20px auto;
    position: relative;
    box-sizing: content-box;
    touch-action: none;
    box-shadow: var(--md-sys-elevation-3);
}

/* Shake animation for invalid moves */
@keyframes shake {
    0%, 100% { transform: translateX(0); }
    10%, 30%, 50%, 70%, 90% { transform: translateX(-5px); }
    20%, 40%, 60%, 80% { transform: translateX(5px); }
}

.shake {
    animation: shake 0.3s var(--md-sys-motion-easing-standard);
}

.tile {
    border-radius: var(--md-sys-shape-corner-medium);
    display: flex;
    justify-content: center;
    align-items: center;
    font-weight: bold;
    position: absolute;
    color: var(--md-sys-color-on-surface);
    transition: transform var(--md-sys-motion-duration-short) var(--md-sys-motion-easing-standard),
                opacity var(--md-sys-motion-duration-short) var(--md-sys-motion-easing-standard);
    box-shadow: var(--md-sys-elevation-1);
}

.tile-1 { background: var(--md-sys-color-surface); color: var(--md-sys-color-on-surface); }
.tile-2 { background: var(--md-sys-color-surface-variant); color: var(--md-sys-color-on-surface-variant); }
.tile-3 { background: var(--md-sys-color-primary-container); color: var(--md-sys-color-on-primary-container); }
.tile-4 { background: var(--md-sys-color-secondary-container); color: var(--md-sys-color-on-secondary-container); }
.tile-5 { background: var(--md-sys-color-tertiary-container); color: var(--md-sys-color-on-tertiary-container); }
.tile-6 { background: var(--md-sys-color-primary); color: var(--md-sys-color-on-primary); }
.tile-7 { background: var(--md-sys-color-secondary); color: var(--md-sys-color-on-secondary); }
.tile-8 { background: var(--md-sys-color-tertiary); color: var(--md-sys-color-on-tertiary); }
.tile-9 {
    background: var(--md-sys-color-error);
    color: var(--md-sys-color-on-error);
    box-shadow: 0 0 30px var(--md-sys-color-error), 0 0 60px var(--md-sys-color-error);
    animation: glow 1.5s var(--md-sys-motion-easing-standard) infinite alternate;
}

@keyframes glow {
    from { box-shadow: 0 0 20px var(--md-sys-color-error), 0 0 40px var(--md-sys-color-error); }
    to { box-shadow: 0 0 30px var(--md-sys-color-error), 0 0 40px var(--md-sys-color-error), 0 0 60px var(--md-sys-color-error), 0 0 80px var(--md-sys-color-error); }
}

.overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(28, 27, 31, 0.8);
    backdrop-filter: blur(8px);
    display: none;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    border-radius: var(--md-sys-shape-corner-large);
    text-align: center;
    z-index: 100;
    animation: fadeIn var(--md-sys-motion-duration-short) var(--md-sys-motion-easing-standard);
}

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

.overlay.active { display: flex; }

.overlay h2 {
    font: var(--md-sys-typescale-headline-large);
    margin: 0 0 12px 0;
    color: var(--md-sys-color-on-surface);
}

.overlay p {
    font: var(--md-sys-typescale-body-large);
    margin: 8px 0;
    color: var(--md-sys-color-on-surface-variant);
}

#win-stats {
    margin: 16px 0;
    padding: 16px;
    background: var(--md-sys-color-surface-variant);
    border-radius: var(--md-sys-shape-corner-large);
}

#win-stats p {
    margin: 8px 0;
    font: var(--md-sys-typescale-body-medium);
}

.overlay-buttons {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
    justify-content: center;
    margin-top: 24px;
}

.restart-btn {
    background: var(--md-sys-color-primary);
    color: var(--md-sys-color-on-primary);
    border: none;
    padding: 12px 24px;
    font: var(--md-sys-typescale-label-large);
    border-radius: var(--md-sys-shape-corner-full);
    cursor: pointer;
    transition: all var(--md-sys-motion-duration-short) var(--md-sys-motion-easing-standard);
    box-shadow: var(--md-sys-elevation-2);
}

.restart-btn:hover {
    box-shadow: var(--md-sys-elevation-3);
    transform: translateY(-2px);
}

#instructions {
    margin-top: 16px;
    font: var(--md-sys-typescale-body-medium);
    line-height: 1.6;
    color: var(--md-sys-color-on-surface-variant);
    background: var(--md-sys-color-surface-variant);
    padding: 16px;
    border-radius: var(--md-sys-shape-corner-large);
}

/* 新手引导 */
.tutorial-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(28, 27, 31, 0.8);
    backdrop-filter: blur(8px);
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    padding: 20px;
}

.tutorial-overlay.active {
    display: flex;
    animation: fadeIn var(--md-sys-motion-duration-short) var(--md-sys-motion-easing-standard);
}

.tutorial-content {
    background: var(--md-sys-color-surface);
    padding: 32px;
    border-radius: var(--md-sys-shape-corner-extra-large);
    max-width: 400px;
    text-align: center;
    box-shadow: var(--md-sys-elevation-5);
}

.tutorial-content h3 {
    font: var(--md-sys-typescale-headline-medium);
    margin-bottom: 16px;
    color: var(--md-sys-color-on-surface);
}

.tutorial-content p {
    font: var(--md-sys-typescale-body-medium);
    line-height: 1.6;
    color: var(--md-sys-color-on-surface-variant);
    margin-bottom: 20px;
}

.tutorial-tips {
    text-align: left;
    background: var(--md-sys-color-surface-variant);
    padding: 16px;
    border-radius: var(--md-sys-shape-corner-large);
    margin-bottom: 20px;
    list-style: none;
}

.tutorial-tips li {
    color: var(--md-sys-color-on-surface);
    margin-bottom: 10px;
    font: var(--md-sys-typescale-body-medium);
}

.tutorial-tips li:last-child {
    margin-bottom: 0;
}

/* 设置面板 */
.settings-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(28, 27, 31, 0.8);
    backdrop-filter: blur(8px);
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    padding: 20px;
}

.settings-overlay.active {
    display: flex;
    animation: fadeIn var(--md-sys-motion-duration-short) var(--md-sys-motion-easing-standard);
}

.settings-content {
    background: var(--md-sys-color-surface);
    padding: 32px;
    border-radius: var(--md-sys-shape-corner-extra-large);
    max-width: 400px;
    width: 100%;
    text-align: center;
    box-shadow: var(--md-sys-elevation-5);
}

.settings-content h3 {
    font: var(--md-sys-typescale-headline-medium);
    margin-bottom: 24px;
    color: var(--md-sys-color-on-surface);
}

.settings-section {
    text-align: left;
    background: var(--md-sys-color-surface-variant);
    padding: 16px;
    border-radius: var(--md-sys-shape-corner-large);
    margin-bottom: 16px;
}

.settings-section h4 {
    color: var(--md-sys-color-on-surface-variant);
    margin-bottom: 12px;
    font: var(--md-sys-typescale-title-medium);
}

.setting-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 8px 0;
    color: var(--md-sys-color-on-surface);
}

/* 统计面板 */
.stats-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(28, 27, 31, 0.8);
    backdrop-filter: blur(8px);
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    padding: 20px;
}

.stats-overlay.active {
    display: flex;
    animation: fadeIn var(--md-sys-motion-duration-short) var(--md-sys-motion-easing-standard);
}

.stats-content {
    background: var(--md-sys-color-surface);
    padding: 32px;
    border-radius: var(--md-sys-shape-corner-extra-large);
    max-width: 400px;
    width: 100%;
    text-align: center;
    box-shadow: var(--md-sys-elevation-5);
}

.stats-content h3 {
    font: var(--md-sys-typescale-headline-medium);
    margin-bottom: 24px;
    color: var(--md-sys-color-on-surface);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
    background: var(--md-sys-color-surface-variant);
    padding: 20px;
    border-radius: var(--md-sys-shape-corner-large);
    margin-bottom: 24px;
}

.stat-item {
    text-align: center;
}

.stat-value {
    font: var(--md-sys-typescale-display-medium);
    color: var(--md-sys-color-primary);
    margin-bottom: 8px;
}

.stat-label {
    font: var(--md-sys-typescale-label-large);
    color: var(--md-sys-color-on-surface-variant);
}

/* 更新提示 */
.update-notification {
    position: fixed;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: var(--md-sys-color-surface);
    color: var(--md-sys-color-on-surface);
    padding: 16px 24px;
    border-radius: var(--md-sys-shape-corner-large);
    box-shadow: var(--md-sys-elevation-5);
    display: none;
    align-items: center;
    gap: 16px;
    z-index: 1001;
    transition: transform var(--md-sys-motion-duration-medium) var(--md-sys-motion-easing-standard);
    border: 1px solid var(--md-sys-color-outline-variant);
}

.update-notification.active {
    display: flex;
    transform: translateX(-50%) translateY(0);
}

.update-notification .notification-buttons {
    display: flex;
    gap: 8px;
}

.update-notification .btn {
    background: var(--md-sys-color-secondary-container);
    padding: 8px 16px;
    font: var(--md-sys-typescale-label-large);
}

/* 分数弹出动画 */
.score-popup {
    position: fixed;
    background: var(--md-sys-color-primary-container);
    color: var(--md-sys-color-on-primary-container);
    padding: 8px 16px;
    border-radius: var(--md-sys-shape-corner-full);
    font: var(--md-sys-typescale-title-large);
    pointer-events: none;
    z-index: 1000;
    opacity: 0;
    transform: translateY(0);
    transition: all 0.8s var(--md-sys-motion-easing-decelerate);
    box-shadow: var(--md-sys-elevation-3);
}

.score-popup.animate {
    opacity: 0;
    transform: translateY(-50px);
}

/* 连击弹出 */
.combo-popup {
    position: absolute;
    background: var(--md-sys-color-tertiary);
    color: var(--md-sys-color-on-tertiary);
    padding: 12px 24px;
    border-radius: var(--md-sys-shape-corner-large);
    font: var(--md-sys-typescale-title-large);
    pointer-events: none;
    z-index: 100;
    opacity: 1;
    box-shadow: var(--md-sys-elevation-3);
    transition: all 1s var(--md-sys-motion-easing-decelerate);
}

.combo-popup .combo-text {
    display: block;
    font: var(--md-sys-typescale-body-medium);
    opacity: 0.9;
}

.combo-popup .bonus-text {
    display: block;
    font: var(--md-sys-typescale-display-medium);
    color: var(--md-sys-color-primary);
}

.combo-popup.animate {
    opacity: 0;
    transform: translateX(-50%) translateY(-50px);
}

/* 响应式 */
@media (max-width: 480px) {
    h1 { 
        font: var(--md-sys-typescale-display-medium);
    }

    .score-box {
        min-width: 60px;
        max-width: 70px;
        padding: 8px 12px;
    }

    .score-label { 
        font: var(--md-sys-typescale-label-large);
    }

    #score, #best, #moves, #timer { 
        font: var(--md-sys-typescale-headline-medium);
    }

    .btn {
        padding: 8px 16px;
        font: var(--md-sys-typescale-label-large);
    }

    #game {
        width: 340px;
        height: 340px;
    }

    .overlay h2 { 
        font: var(--md-sys-typescale-headline-medium);
    }
    
    .overlay p { 
        font: var(--md-sys-typescale-body-medium);
    }

    #instructions { 
        font: var(--md-sys-typescale-body-small);
    }

    .tutorial-content h3 { 
        font: var(--md-sys-typescale-headline-small);
    }
    
    .tutorial-content p { 
        font: var(--md-sys-typescale-body-small);
    }

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

    .update-notification {
        flex-direction: column;
        bottom: 10px;
        width: 90%;
    }

    .update-notification .notification-buttons {
        width: 100%;
        justify-content: center;
    }
}

/* 全面屏适配 */
@supports (padding: max(0px)) {
    body {
        padding-left: env(safe-area-inset-left);
        padding-right: env(safe-area-inset-right);
    }
}