/* ============================================
   FLOW SYNC - Stylesheet
   ============================================ */

/* ============================================
   IMPORTS & FONTS
   ============================================ */
@import url('https://fonts.googleapis.com/css2?family=Orbitron:wght@400;700&family=Quicksand:wght@300;500&display=swap');

/* ============================================
   CSS VARIABLES (Design Tokens)
   ============================================ */
:root {
    /* Colors */
    --color-bg-primary: #050505;
    --color-bg-overlay: rgba(0, 0, 0, 0.7);
    --color-text-primary: rgba(255, 255, 255, 0.8);
    --color-text-secondary: rgba(255, 255, 255, 0.6);
    --color-text-tertiary: rgba(255, 255, 255, 0.5);
    --color-accent-cyan: #00f2ff;
    --color-accent-purple: #bd00ff;
    --color-accent-glow: rgba(0, 242, 255, 0.4);
    --color-button-power: #00f2ff;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Typography */
    --font-primary: 'Quicksand', sans-serif;
    --font-display: 'Orbitron', sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.2rem;
    --font-size-xl: 1.5rem;
    --font-size-2xl: 2rem;
    --font-size-3xl: 3rem;
    --font-size-4xl: 4rem;
    --font-size-5xl: 5rem;
    
    /* Effects */
    --blur-backdrop: blur(5px);
    --blur-overlay: blur(4px);
    --shadow-glow: 0 0 15px rgba(0, 242, 255, 0.4);
    --shadow-canvas: 0 0 50px rgba(0, 255, 255, 0.05);
    --shadow-text: 0 0 10px rgba(255, 255, 255, 0.3);
    --shadow-title: 0 0 20px #00f2ff;
    
    /* Transitions */
    --transition-fast: 0.2s;
    --transition-base: 0.3s;
    --transition-slow: 0.5s;
    
    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 30px;
    
    /* Z-index Layers */
    --z-base: 1;
    --z-ui: 10;
    --z-overlay: 20;
}

/* ============================================
   RESET & BASE STYLES
   ============================================ */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    background-color: var(--color-bg-primary);
    overflow: hidden;
    touch-action: none;
    font-family: var(--font-primary);
    color: var(--color-text-primary);
    width: 100vw;
    height: 100vh;
    position: fixed;
    top: 0;
    left: 0;
}

/* ============================================
   GAME CONTAINER
   ============================================ */
#game-container {
    position: relative;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: var(--spacing-sm);
    overflow: hidden;
    min-height: 100vh;
    min-width: 100vw;
}

/* ============================================
   CANVAS
   ============================================ */
canvas {
    box-shadow: 
        0 0 60px rgba(0, 242, 255, 0.15),
        0 0 120px rgba(0, 242, 255, 0.08),
        0 8px 40px rgba(0, 0, 0, 0.5),
        0 2px 8px rgba(0, 0, 0, 0.3),
        inset 0 1px 0 rgba(255, 255, 255, 0.08),
        inset 0 -1px 0 rgba(0, 0, 0, 0.5);
    border-radius: var(--radius-md);
    transition: transform var(--transition-base) ease, box-shadow var(--transition-base) ease;
    max-width: 100%;
    max-height: 100%;
    width: auto;
    height: auto;
    display: block;
    background: transparent;
    border: none;
    position: relative;
    backdrop-filter: blur(10px);
    overflow: hidden;
    object-fit: contain;
    touch-action: manipulation;
    -webkit-tap-highlight-color: transparent;
    /* Optimize rendering performance */
    image-rendering: -webkit-optimize-contrast;
    image-rendering: crisp-edges;
    will-change: transform;
}

/* ============================================
   UI LAYER
   ============================================ */
.ui-layer {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    padding: var(--spacing-xs);
    z-index: var(--z-ui);
    pointer-events: none;
}

.ui-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
    padding: 0;
}

.ui-header-left {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    flex-shrink: 0;
}

.ui-header-right {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    flex-shrink: 0;
}

.level-display {
    font-size: var(--font-size-sm);
    font-weight: 700;
    color: var(--color-accent-cyan);
    font-family: var(--font-display);
    transition: all var(--transition-base) ease;
    pointer-events: auto;
    text-shadow: 0 0 8px rgba(0, 242, 255, 0.6), 0 0 15px rgba(0, 242, 255, 0.3);
    letter-spacing: 1px;
    height: 44px;
    display: flex;
    align-items: center;
    padding: 0 var(--spacing-sm);
    margin: 0;
    background: rgba(0, 242, 255, 0.05);
    border: 2px solid rgba(0, 242, 255, 0.2);
    border-radius: var(--radius-sm);
    backdrop-filter: var(--blur-backdrop);
    box-sizing: border-box;
}

.moves-needed-display {
    font-size: var(--font-size-sm);
    font-weight: 700;
    color: var(--color-accent-cyan);
    font-family: var(--font-display);
    transition: all var(--transition-base) ease;
    pointer-events: auto;
    text-shadow: 0 0 8px rgba(0, 242, 255, 0.6), 0 0 15px rgba(0, 242, 255, 0.3);
    letter-spacing: 1px;
    height: 44px;
    display: flex;
    align-items: center;
    padding: 0 var(--spacing-sm);
    margin: 0 0 0 var(--spacing-xs);
    background: rgba(0, 242, 255, 0.05);
    border: 2px solid rgba(0, 242, 255, 0.2);
    border-radius: var(--radius-sm);
    backdrop-filter: var(--blur-backdrop);
    box-sizing: border-box;
    min-width: 90px;
    justify-content: center;
}


.btn.btn-icon {
    width: 44px;
    height: 44px;
    padding: 0 !important;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-sm) !important;
    background: var(--color-button-power);
    backdrop-filter: var(--blur-backdrop);
    border: 2px solid var(--color-button-power);
    color: rgba(255, 255, 255, 1);
    pointer-events: auto;
    min-width: 44px;
    min-height: 44px;
    text-transform: none;
    font-size: 0;
    transition: all var(--transition-base) ease;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.25);
}

.btn-icon svg {
    width: 24px;
    height: 24px;
    stroke: rgba(255, 255, 255, 1);
    stroke-width: 2.5;
    fill: none;
    transition: all var(--transition-base) ease;
}

.btn-icon:hover {
    background: var(--color-button-power);
    border-color: var(--color-button-power);
    filter: brightness(1.2);
    box-shadow: 0 3px 10px rgba(0, 0, 0, 0.3), 0 0 15px var(--color-button-power);
    transform: translateY(-2px) scale(1.05);
}

.btn-icon.disabled {
    opacity: 0.5;
    cursor: not-allowed;
    pointer-events: none;
}

/* Hint button specific styles */
#hint-btn {
    position: relative;
}

.hint-count {
    position: absolute;
    top: -8px;
    right: -8px;
    background: var(--color-accent-purple);
    color: white;
    font-size: 0.7rem;
    font-weight: 700;
    font-family: var(--font-display);
    border-radius: 50%;
    width: 20px;
    height: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px solid var(--color-bg-primary);
    box-shadow: 0 0 8px rgba(189, 0, 255, 0.6);
}

.btn-icon:hover svg {
    transform: scale(1.1);
    stroke: rgba(255, 255, 255, 1);
}

.btn-icon:active {
    transform: translateY(0) scale(0.98);
    box-shadow: 0 1px 4px rgba(0, 0, 0, 0.3);
}

.btn-icon:focus-visible {
    outline: 2px solid var(--color-button-power);
    outline-offset: 3px;
    box-shadow: 0 0 8px var(--color-button-power);
}

/* ============================================
   TYPOGRAPHY
   ============================================ */
h1 {
    font-family: var(--font-display);
    font-size: var(--font-size-xl);
    font-weight: 700;
    letter-spacing: 1px;
    background: linear-gradient(90deg, var(--color-accent-cyan), var(--color-accent-purple));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-xs);
    line-height: 1.2;
}


/* ============================================
   BUTTONS
   ============================================ */
.btn {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: var(--blur-backdrop);
    border: 1px solid rgba(255, 255, 255, 0.2);
    padding: 10px 20px;
    border-radius: var(--radius-lg);
    color: white;
    cursor: pointer;
    transition: all var(--transition-fast) ease;
    font-family: var(--font-display);
    text-transform: uppercase;
    font-size: var(--font-size-sm);
    font-weight: 400;
    pointer-events: auto;
    outline: none;
    user-select: none;
    -webkit-tap-highlight-color: transparent;
}

.btn:hover {
    background: rgba(255, 255, 255, 0.2);
    box-shadow: var(--shadow-glow);
    transform: translateY(-2px);
}

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

.btn:focus-visible {
    outline: 2px solid var(--color-accent-cyan);
    outline-offset: 2px;
}

.btn-large {
    font-size: var(--font-size-lg);
    padding: 16px 48px;
    font-weight: 700;
    letter-spacing: 2px;
    box-shadow: 0 0 20px rgba(0, 242, 255, 0.3), inset 0 0 15px rgba(0, 242, 255, 0.08);
}

.btn-large:hover {
    box-shadow: 0 0 30px rgba(0, 242, 255, 0.5), 0 0 60px rgba(0, 242, 255, 0.3), inset 0 0 20px rgba(0, 242, 255, 0.15);
    transform: translateY(-4px) scale(1.03);
}

/* ============================================
   START OVERLAY
   ============================================ */
#start-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--color-bg-overlay);
    backdrop-filter: var(--blur-overlay);
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    z-index: calc(var(--z-overlay) + 1);
    transition: opacity var(--transition-slow) ease, visibility var(--transition-slow) ease;
}

#start-overlay[aria-hidden="true"] {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
}

.start-modal {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0;
    padding: var(--spacing-lg) var(--spacing-md);
    background: linear-gradient(135deg, rgba(5, 5, 5, 0.98), rgba(10, 10, 20, 0.98));
    border: 1px solid rgba(0, 242, 255, 0.4);
    border-radius: var(--radius-md);
    box-shadow: 
        0 0 30px rgba(0, 242, 255, 0.4),
        0 0 60px rgba(0, 242, 255, 0.2),
        0 8px 32px rgba(0, 0, 0, 0.5),
        inset 0 1px 0 rgba(255, 255, 255, 0.1),
        inset 0 0 20px rgba(0, 242, 255, 0.05);
    backdrop-filter: var(--blur-backdrop);
    max-width: 450px;
    width: 85%;
    max-height: 95vh;
    overflow-y: auto;
    overflow-x: hidden;
    animation: fadeIn 0.8s ease-in-out, slideUp 0.8s ease-in-out;
    position: relative;
    -webkit-overflow-scrolling: touch;
}

.start-modal::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, transparent, var(--color-accent-cyan), transparent);
    animation: shimmer 3s infinite;
}

@keyframes shimmer {
    0%, 100% { opacity: 0.3; }
    50% { opacity: 1; }
}

.logo-container {
    text-align: center;
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid rgba(0, 242, 255, 0.2);
    width: 100%;
}

.logo-title {
    font-family: var(--font-display);
    font-size: var(--font-size-2xl);
    font-weight: 700;
    letter-spacing: 0.15em;
    color: var(--color-accent-cyan);
    margin-bottom: var(--spacing-xs);
    line-height: 1.2;
    text-shadow: 0 0 15px rgba(0, 242, 255, 0.5), 0 0 30px rgba(0, 242, 255, 0.3);
}

.logo-subtitle {
    font-size: var(--font-size-xs);
    color: var(--color-text-secondary);
    font-family: var(--font-display);
    text-transform: uppercase;
    letter-spacing: 0.2em;
    font-weight: 400;
    margin-top: var(--spacing-xs);
}

.game-instructions {
    width: 100%;
    text-align: left;
    padding: 0;
    margin-bottom: var(--spacing-md);
}

.game-instructions .instructions-title {
    font-family: var(--font-display);
    font-size: var(--font-size-base);
    font-weight: 700;
    color: var(--color-accent-cyan);
    margin-bottom: var(--spacing-md);
    letter-spacing: 2px;
    text-transform: uppercase;
    text-align: center;
    padding-bottom: var(--spacing-sm);
    border-bottom: 1px solid rgba(0, 242, 255, 0.15);
    text-shadow: 0 0 10px rgba(0, 242, 255, 0.4);
}

.game-instructions .instructions-content {
    color: var(--color-text-secondary);
    font-size: var(--font-size-xs);
    line-height: 1.6;
    text-align: left;
    margin: 0;
    padding: var(--spacing-sm) var(--spacing-xs) 0;
}

.game-instructions .instructions-content p {
    margin: 0 0 var(--spacing-sm) 0;
    padding: 0;
    color: var(--color-text-secondary);
    display: flex;
    flex-direction: row;
    align-items: baseline;
    gap: 0.5rem;
    line-height: 1.6;
}

.game-instructions .instructions-content p::before {
    content: '▸';
    color: var(--color-accent-cyan);
    font-size: inherit;
    line-height: inherit;
    flex-shrink: 0;
    flex-grow: 0;
    width: auto;
    display: block;
    margin: 0;
    padding: 0;
    align-self: baseline;
}

.game-instructions .instructions-content p:last-child {
    margin-bottom: 0;
}

.start-buttons {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    width: 100%;
    margin-top: var(--spacing-md);
    padding-top: var(--spacing-md);
    border-top: 1px solid rgba(0, 242, 255, 0.2);
}

.start-buttons .btn {
    width: 100%;
    margin: 0;
}

/* ============================================
   LEVEL SELECTION OVERLAY
   ============================================ */
#level-selection-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--color-bg-overlay);
    backdrop-filter: var(--blur-overlay);
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    z-index: calc(var(--z-overlay) + 3);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transition: opacity var(--transition-slow) ease, visibility var(--transition-slow) ease;
}

#level-selection-overlay[aria-hidden="false"] {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
}

.level-selection-modal {
    background: linear-gradient(135deg, rgba(5, 5, 5, 0.98), rgba(10, 10, 20, 0.98));
    border: 1px solid rgba(0, 242, 255, 0.4);
    border-radius: var(--radius-md);
    box-shadow: 
        0 0 30px rgba(0, 242, 255, 0.4),
        0 0 60px rgba(0, 242, 255, 0.2),
        0 8px 32px rgba(0, 0, 0, 0.5),
        inset 0 1px 0 rgba(255, 255, 255, 0.1),
        inset 0 0 20px rgba(0, 242, 255, 0.05);
    backdrop-filter: var(--blur-backdrop);
    max-width: 90%;
    max-height: 90vh;
    width: 100%;
    padding: var(--spacing-lg);
    overflow-y: auto;
    overflow-x: hidden;
    animation: fadeIn 0.8s ease-in-out, slideUp 0.8s ease-in-out;
    position: relative;
    -webkit-overflow-scrolling: touch;
}

.level-selection-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid rgba(0, 242, 255, 0.2);
}

.level-selection-title {
    font-family: var(--font-display);
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--color-accent-cyan);
    letter-spacing: 0.1em;
    text-shadow: 0 0 15px rgba(0, 242, 255, 0.5), 0 0 30px rgba(0, 242, 255, 0.3);
    margin: 0;
}

.level-selection-close {
    background: rgba(255, 255, 255, 0.1) !important;
    border-color: rgba(255, 255, 255, 0.2) !important;
}

.level-selection-close:hover {
    background: rgba(255, 255, 255, 0.2) !important;
    border-color: rgba(0, 242, 255, 0.4) !important;
}

.level-selection-content {
    width: 100%;
}

.level-path-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md) 0;
}

.level-path-row {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    flex-wrap: wrap;
}

.level-node {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    position: relative;
    transition: all var(--transition-base) ease;
    border: 3px solid;
    background: rgba(20, 20, 25, 0.8);
    backdrop-filter: var(--blur-backdrop);
}

.level-node.locked {
    border-color: rgba(100, 100, 110, 0.5);
    background: rgba(15, 15, 20, 0.6);
    opacity: 0.5;
}

.level-node.unlocked {
    border-color: rgba(0, 242, 255, 0.4);
    background: rgba(0, 242, 255, 0.05);
    box-shadow: 0 0 10px rgba(0, 242, 255, 0.2);
}

.level-node.unlocked:hover {
    transform: scale(1.1);
    border-color: var(--color-accent-cyan);
    box-shadow: 0 0 20px rgba(0, 242, 255, 0.5);
    background: rgba(0, 242, 255, 0.1);
}

.level-node.completed {
    border-color: var(--color-accent-cyan);
    background: rgba(0, 242, 255, 0.15);
    box-shadow: 0 0 15px rgba(0, 242, 255, 0.4);
}

.level-node.current {
    border-color: var(--color-accent-purple);
    background: rgba(189, 0, 255, 0.15);
    box-shadow: 0 0 20px rgba(189, 0, 255, 0.5);
    animation: pulse-current 2s ease-in-out infinite;
}

@keyframes pulse-current {
    0%, 100% {
        transform: scale(1);
        box-shadow: 0 0 20px rgba(189, 0, 255, 0.5);
    }
    50% {
        transform: scale(1.05);
        box-shadow: 0 0 30px rgba(189, 0, 255, 0.7);
    }
}

.level-number {
    font-family: var(--font-display);
    font-size: var(--font-size-base);
    font-weight: 700;
    color: var(--color-text-primary);
    line-height: 1;
    margin-bottom: 2px;
}

.level-node.completed .level-number {
    color: var(--color-accent-cyan);
}

.level-node.current .level-number {
    color: var(--color-accent-purple);
}

.level-status {
    font-size: var(--font-size-sm);
    line-height: 1;
    color: var(--color-accent-cyan);
}

.level-node.locked .level-status {
    color: rgba(100, 100, 110, 0.6);
    font-size: var(--font-size-xs);
}

.level-node.completed .level-status {
    color: var(--color-accent-cyan);
    font-weight: 700;
}

.level-connector {
    width: 40px;
    height: 3px;
    background: rgba(100, 100, 110, 0.3);
    transition: all var(--transition-base) ease;
    position: relative;
}

.level-connector.active {
    background: linear-gradient(90deg, var(--color-accent-cyan), var(--color-accent-purple));
    box-shadow: 0 0 8px rgba(0, 242, 255, 0.4);
}

.level-connector::before {
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 0;
    height: 100%;
    background: linear-gradient(90deg, var(--color-accent-cyan), var(--color-accent-purple));
    transition: width var(--transition-slow) ease;
}

.level-connector.active::before {
    width: 100%;
    animation: flow-connector 2s ease-in-out infinite;
}

@keyframes flow-connector {
    0%, 100% {
        opacity: 0.6;
    }
    50% {
        opacity: 1;
    }
}

.level-connector-vertical {
    width: 3px;
    height: 30px;
    background: rgba(100, 100, 110, 0.3);
    transition: all var(--transition-base) ease;
    position: relative;
}

.level-connector-vertical.active {
    background: linear-gradient(180deg, var(--color-accent-cyan), var(--color-accent-purple));
    box-shadow: 0 0 8px rgba(0, 242, 255, 0.4);
}

.level-connector-vertical::before {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 100%;
    height: 0;
    background: linear-gradient(180deg, var(--color-accent-cyan), var(--color-accent-purple));
    transition: height var(--transition-slow) ease;
}

.level-connector-vertical.active::before {
    height: 100%;
    animation: flow-connector-vertical 2s ease-in-out infinite;
}

@keyframes flow-connector-vertical {
    0%, 100% {
        opacity: 0.6;
    }
    50% {
        opacity: 1;
    }
}

/* ============================================
   INSTRUCTIONS OVERLAY
   ============================================ */
#instructions-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--color-bg-overlay);
    backdrop-filter: var(--blur-overlay);
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transition: opacity var(--transition-slow) ease, visibility var(--transition-slow) ease;
    z-index: calc(var(--z-overlay) + 2);
}

#instructions-overlay.active {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
}

.instructions-modal {
    background: rgba(5, 5, 5, 0.95);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    padding: var(--spacing-xl);
    max-width: 500px;
    width: 90%;
    max-height: 95vh;
    overflow-y: auto;
    overflow-x: hidden;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-lg);
    animation: fadeIn 0.5s ease-in-out;
    -webkit-overflow-scrolling: touch;
}

.instructions-title {
    font-family: var(--font-display);
    font-size: var(--font-size-3xl);
    font-weight: 700;
    color: var(--color-accent-cyan);
    margin-bottom: var(--spacing-sm);
    letter-spacing: 0.1em;
    text-align: center;
}

.instructions-content {
    color: var(--color-text-primary);
    font-size: var(--font-size-base);
    line-height: 1.6;
    text-align: center;
}

.instructions-content p {
    margin-bottom: var(--spacing-md);
}

.instructions-content p:last-child {
    margin-bottom: 0;
}

/* ============================================
   SOLUTION OVERLAY
   ============================================ */
.solution-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    padding-top: 100px;
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transition: opacity var(--transition-slow) ease, visibility var(--transition-slow) ease;
    z-index: calc(var(--z-overlay) + 1);
    background: transparent;
}

.solution-overlay.active {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
}

.solution-overlay .btn {
    pointer-events: auto;
    z-index: calc(var(--z-overlay) + 2);
    animation: fadeIn 0.5s ease-in-out;
    margin-top: 0;
}

/* ============================================
   WIN OVERLAY
   ============================================ */
#win-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--color-bg-overlay);
    backdrop-filter: var(--blur-overlay);
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transition: opacity var(--transition-slow) ease, visibility var(--transition-slow) ease;
    z-index: var(--z-overlay);
}

#win-overlay.active {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
}

.win-title {
    font-family: var(--font-display);
    font-size: var(--font-size-5xl);
    font-weight: 700;
    color: white;
    margin-bottom: var(--spacing-sm);
    letter-spacing: 0.1em;
    text-shadow: var(--shadow-title);
    line-height: 1.2;
}

.win-subtitle {
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-md);
    font-size: var(--font-size-base);
}

/* ============================================
   GAME OVER OVERLAY
   ============================================ */
#game-over-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--color-bg-overlay);
    backdrop-filter: var(--blur-overlay);
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transition: opacity var(--transition-slow) ease, visibility var(--transition-slow) ease;
    z-index: calc(var(--z-overlay) + 2);
}

#game-over-overlay.active {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
}

.game-over-title {
    font-family: var(--font-display);
    font-size: var(--font-size-5xl);
    font-weight: 700;
    color: #ff4444;
    margin-bottom: var(--spacing-sm);
    letter-spacing: 0.1em;
    text-shadow: 0 0 20px #ff4444, 0 0 40px rgba(255, 68, 68, 0.5);
    line-height: 1.2;
    animation: pulse-game-over 2s ease-in-out infinite;
}

@keyframes pulse-game-over {
    0%, 100% {
        opacity: 1;
        transform: scale(1);
    }
    50% {
        opacity: 0.9;
        transform: scale(1.05);
    }
}

.game-over-subtitle {
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-md);
    font-size: var(--font-size-base);
}


/* ============================================
   ANIMATIONS
   ============================================ */
.fade-in {
    animation: fadeIn 1s ease-in-out;
}

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

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(30px) scale(0.95);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */

/* ============================================
   DESKTOP (≥1025px) - Base Styles
   ============================================ */
@media screen and (min-width: 1025px) {
    #game-container {
        padding: var(--spacing-md);
    }
    
    .start-modal {
        max-width: 500px;
    }
    
    .instructions-modal {
        max-width: 550px;
        padding: var(--spacing-xl);
    }
}

/* ============================================
   TABLET LANDSCAPE (769px-1024px)
   ============================================ */
@media screen and (min-width: 769px) and (max-width: 1024px) {
    :root {
        --font-size-3xl: 2.5rem;
        --font-size-5xl: 4rem;
        --spacing-lg: 1.75rem;
    }
    
    #game-container {
        padding: var(--spacing-sm);
    }
    
    .ui-layer {
        padding: var(--spacing-xs) var(--spacing-sm);
    }
    
    .level-display,
    .moves-needed-display {
        font-size: var(--font-size-sm);
        height: 42px;
        padding: 0 var(--spacing-sm);
    }
    
    .moves-needed-display {
        min-width: 85px;
        font-size: var(--font-size-xs);
    }
    
    .btn-icon {
        width: 42px;
        height: 42px;
        min-width: 42px;
        min-height: 42px;
    }
    
    .btn-icon svg {
        width: 23px;
        height: 23px;
    }
    
    .start-modal {
        max-width: 280px;
        padding: var(--spacing-lg) var(--spacing-md);
    }
    
    .logo-title {
        font-size: var(--font-size-2xl);
        letter-spacing: 2px;
    }
    
    .instructions-modal {
        max-width: 500px;
        padding: var(--spacing-lg);
    }
    
    .win-title,
    .game-over-title {
        font-size: var(--font-size-4xl);
    }
    
    .btn-large {
        font-size: var(--font-size-lg);
        padding: 14px 40px;
    }
}

/* ============================================
   TABLET PORTRAIT (641px-768px)
   ============================================ */
@media screen and (min-width: 641px) and (max-width: 768px) {
    :root {
        --font-size-3xl: 2rem;
        --font-size-5xl: 3rem;
        --spacing-lg: 1.5rem;
        --spacing-md: 1.25rem;
    }
    
    #game-container {
        padding: var(--spacing-xs) var(--spacing-sm);
    }
    
    .ui-layer {
        padding: var(--spacing-xs);
    }
    
    .ui-header-left,
    .ui-header-right {
        gap: var(--spacing-xs);
    }
    
    .level-display,
    .moves-needed-display {
        font-size: var(--font-size-xs);
        height: 40px;
        padding: 0 var(--spacing-xs);
        letter-spacing: 0.5px;
    }
    
    .moves-needed-display {
        min-width: 80px;
        font-size: 0.7rem;
    }
    
    .btn-icon {
        width: 40px;
        height: 40px;
        min-width: 40px;
        min-height: 40px;
    }
    
    .btn-icon svg {
        width: 22px;
        height: 22px;
    }
    
    .start-modal {
        max-width: 85%;
        padding: var(--spacing-md) var(--spacing-sm);
    }
    
    .logo-title {
        font-size: var(--font-size-xl);
        letter-spacing: 2px;
    }
    
    .logo-subtitle {
        font-size: var(--font-size-xs);
    }
    
    .game-instructions .instructions-title {
        font-size: var(--font-size-base);
        margin-bottom: var(--spacing-sm);
        padding-bottom: var(--spacing-xs);
    }
    
    .game-instructions .instructions-content {
        font-size: var(--font-size-xs);
        padding: var(--spacing-xs);
    }
    
    .instructions-modal {
        max-width: 85%;
        padding: var(--spacing-md);
    }
    
    .instructions-title {
        font-size: var(--font-size-2xl);
    }
    
    .instructions-content {
        font-size: var(--font-size-sm);
    }
    
    .win-title,
    .game-over-title {
        font-size: var(--font-size-3xl);
    }
    
    .win-subtitle,
    .game-over-subtitle {
        font-size: var(--font-size-base);
    }
    
    .btn-large {
        font-size: var(--font-size-base);
        padding: 12px 32px;
        letter-spacing: 1.5px;
    }
}

/* ============================================
   LEVEL SELECTION RESPONSIVE
   ============================================ */
@media screen and (max-width: 768px) {
    .level-selection-modal {
        padding: var(--spacing-md);
        max-width: 95%;
    }
    
    .level-selection-title {
        font-size: var(--font-size-xl);
    }
    
    .level-node {
        width: 50px;
        height: 50px;
    }
    
    .level-number {
        font-size: var(--font-size-sm);
    }
    
    .level-status {
        font-size: var(--font-size-xs);
    }
    
    .level-connector {
        width: 30px;
    }
    
    .level-connector-vertical {
        height: 20px;
    }
}

@media screen and (max-width: 480px) {
    .level-selection-modal {
        padding: var(--spacing-sm);
        max-width: 98%;
    }
    
    .level-selection-header {
        margin-bottom: var(--spacing-sm);
        padding-bottom: var(--spacing-sm);
    }
    
    .level-selection-title {
        font-size: var(--font-size-lg);
    }
    
    .level-node {
        width: 45px;
        height: 45px;
    }
    
    .level-number {
        font-size: var(--font-size-xs);
    }
    
    .level-status {
        font-size: 0.65rem;
    }
    
    .level-connector {
        width: 25px;
        height: 2px;
    }
    
    .level-connector-vertical {
        height: 15px;
        width: 2px;
    }
    
    .level-path-container {
        gap: var(--spacing-sm);
        padding: var(--spacing-sm) 0;
    }
    
    .level-path-row {
        gap: 4px;
    }
}

/* ============================================
   MOBILE (≤640px)
   ============================================ */
@media screen and (max-width: 640px) {
    :root {
        --font-size-3xl: 1.75rem;
        --font-size-5xl: 2.5rem;
        --spacing-lg: 1.25rem;
        --spacing-md: 1rem;
    }
    
    #game-container {
        padding: var(--spacing-xs);
    }
    
    .ui-layer {
        padding: var(--spacing-xs);
    }
    
    .ui-header-left,
    .ui-header-right {
        gap: var(--spacing-xs);
    }
    
    .level-display,
    .moves-needed-display {
        font-size: var(--font-size-xs);
        height: 38px;
        padding: 0 10px;
        letter-spacing: 0.5px;
    }
    
    .moves-needed-display {
        min-width: 75px;
        font-size: 0.65rem;
    }
    
    .btn-icon {
        width: 38px;
        height: 38px;
        min-width: 38px;
        min-height: 38px;
    }
    
    .btn-icon svg {
        width: 21px;
        height: 21px;
    }
    
    .start-modal {
        max-width: 90%;
        padding: var(--spacing-md) var(--spacing-sm);
    }
    
    .logo-title {
        font-size: var(--font-size-lg);
        letter-spacing: 1.5px;
    }
    
    .logo-subtitle {
        font-size: var(--font-size-xs);
        letter-spacing: 1.5px;
    }
    
    .game-instructions {
        margin-bottom: var(--spacing-sm);
    }
    
    .game-instructions .instructions-title {
        font-size: var(--font-size-sm);
        margin-bottom: var(--spacing-sm);
        padding-bottom: var(--spacing-xs);
    }
    
    .game-instructions .instructions-content {
        font-size: var(--font-size-xs);
        padding: var(--spacing-xs);
        line-height: 1.5;
    }
    
    .instructions-modal {
        max-width: 90%;
        padding: var(--spacing-md);
    }
    
    .instructions-title {
        font-size: var(--font-size-xl);
    }
    
    .instructions-content {
        font-size: var(--font-size-sm);
    }
    
    .win-title,
    .game-over-title {
        font-size: var(--font-size-2xl);
    }
    
    .win-subtitle,
    .game-over-subtitle {
        font-size: var(--font-size-sm);
    }
    
    .btn {
        font-size: var(--font-size-xs);
        padding: 9px 18px;
    }
    
    .btn-large {
        font-size: var(--font-size-sm);
        padding: 11px 28px;
        letter-spacing: 1px;
    }
    
    /* Reduce shadow complexity on mobile for better performance */
    canvas {
        box-shadow: 
            0 0 30px rgba(0, 242, 255, 0.12),
            0 4px 20px rgba(0, 0, 0, 0.4),
            0 1px 4px rgba(0, 0, 0, 0.3);
    }
}

/* ============================================
   SMALL MOBILE (≤480px)
   ============================================ */
@media screen and (max-width: 480px) {
    :root {
        --font-size-3xl: 1.5rem;
        --font-size-5xl: 2rem;
        --spacing-lg: 1rem;
        --spacing-md: 0.875rem;
        --spacing-sm: 0.75rem;
    }
    
    html {
        font-size: 15px;
    }
    
    #game-container {
        padding: var(--spacing-xs);
    }
    
    .ui-layer {
        padding: var(--spacing-xs);
    }
    
    .ui-header {
        gap: var(--spacing-xs);
    }
    
    .ui-header-left,
    .ui-header-right {
        gap: 4px;
    }
    
    .level-display,
    .moves-needed-display {
        font-size: 0.7rem;
        height: 36px;
        padding: 0 8px;
        letter-spacing: 0.3px;
    }
    
    .moves-needed-display {
        min-width: 70px;
        font-size: 0.6rem;
    }
    
    .btn-icon {
        width: 36px;
        height: 36px;
        min-width: 36px;
        min-height: 36px;
    }
    
    .btn-icon svg {
        width: 20px;
        height: 20px;
    }
    
    .start-modal {
        max-width: 95%;
        padding: var(--spacing-sm) var(--spacing-xs);
        border-radius: var(--radius-sm);
    }
    
    .logo-container {
        padding-bottom: var(--spacing-sm);
        margin-bottom: var(--spacing-sm);
    }
    
    .logo-title {
        font-size: var(--font-size-base);
        letter-spacing: 1px;
        margin-bottom: var(--spacing-xs);
    }
    
    .logo-subtitle {
        font-size: 0.65rem;
        letter-spacing: 1px;
    }
    
    .game-instructions {
        margin-bottom: var(--spacing-sm);
    }
    
    .game-instructions .instructions-title {
        font-size: var(--font-size-xs);
        margin-bottom: var(--spacing-xs);
        padding-bottom: var(--spacing-xs);
        letter-spacing: 1px;
    }
    
    .game-instructions .instructions-content {
        font-size: 0.7rem;
        padding: var(--spacing-xs) 0 0;
        line-height: 1.5;
    }
    
    .game-instructions .instructions-content p {
        margin-bottom: var(--spacing-xs);
    }
    
    .start-buttons {
        margin-top: var(--spacing-sm);
        padding-top: var(--spacing-sm);
        gap: var(--spacing-xs);
    }
    
    .instructions-modal {
        max-width: 95%;
        padding: var(--spacing-sm);
        gap: var(--spacing-sm);
    }
    
    .instructions-title {
        font-size: var(--font-size-lg);
        margin-bottom: var(--spacing-xs);
    }
    
    .instructions-content {
        font-size: var(--font-size-xs);
        line-height: 1.5;
    }
    
    .instructions-content p {
        margin-bottom: var(--spacing-xs);
    }
    
    .win-title,
    .game-over-title {
        font-size: var(--font-size-2xl);
        letter-spacing: 0.05em;
        margin-bottom: var(--spacing-xs);
    }
    
    .win-subtitle,
    .game-over-subtitle {
        font-size: var(--font-size-xs);
        margin-bottom: var(--spacing-sm);
    }
    
    .btn {
        font-size: var(--font-size-xs);
        padding: 8px 16px;
        border-radius: var(--radius-sm);
    }
    
    .btn-large {
        font-size: var(--font-size-xs);
        padding: 10px 24px;
        letter-spacing: 0.5px;
    }
    
    canvas {
        border-radius: var(--radius-sm);
    }
}

/* ============================================
   LANDSCAPE MOBILE (orientation: landscape)
   ============================================ */
@media screen and (orientation: landscape) and (max-height: 640px) {
    :root {
        --spacing-lg: 1rem;
        --spacing-md: 0.75rem;
    }
    
    #game-container {
        padding: var(--spacing-xs);
        justify-content: center;
    }
    
    .ui-layer {
        padding: var(--spacing-xs) var(--spacing-sm);
    }
    
    .level-display,
    .moves-needed-display {
        height: 36px;
        font-size: var(--font-size-xs);
        padding: 0 8px;
    }
    
    .moves-needed-display {
        min-width: 70px;
        font-size: 0.65rem;
    }
    
    .btn-icon {
        width: 36px;
        height: 36px;
        min-width: 36px;
        min-height: 36px;
    }
    
    .btn-icon svg {
        width: 20px;
        height: 20px;
    }
    
    .start-modal {
        max-width: 55%;
        max-height: 90vh;
        overflow-y: auto;
        padding: var(--spacing-sm);
    }
    
    .logo-container {
        padding-bottom: var(--spacing-xs);
        margin-bottom: var(--spacing-xs);
    }
    
    .logo-title {
        font-size: var(--font-size-lg);
        letter-spacing: 1px;
        margin-bottom: var(--spacing-xs);
    }
    
    .logo-subtitle {
        font-size: var(--font-size-xs);
    }
    
    .game-instructions {
        margin-bottom: var(--spacing-xs);
    }
    
    .game-instructions .instructions-title {
        font-size: var(--font-size-xs);
        margin-bottom: var(--spacing-xs);
        padding-bottom: var(--spacing-xs);
    }
    
    .game-instructions .instructions-content {
        font-size: 0.7rem;
        padding: var(--spacing-xs) 0 0;
    }
    
    .game-instructions .instructions-content p {
        margin-bottom: 6px;
    }
    
    .start-buttons {
        margin-top: var(--spacing-xs);
        padding-top: var(--spacing-xs);
        gap: var(--spacing-xs);
    }
    
    .instructions-modal {
        max-width: 85%;
        max-height: 90vh;
        overflow-y: auto;
        padding: var(--spacing-sm);
        gap: var(--spacing-xs);
    }
    
    .instructions-title {
        font-size: var(--font-size-lg);
        margin-bottom: var(--spacing-xs);
    }
    
    .instructions-content {
        font-size: var(--font-size-xs);
    }
    
    .instructions-content p {
        margin-bottom: var(--spacing-xs);
    }
    
    .win-title,
    .game-over-title {
        font-size: var(--font-size-xl);
        margin-bottom: var(--spacing-xs);
    }
    
    .win-subtitle,
    .game-over-subtitle {
        font-size: var(--font-size-xs);
        margin-bottom: var(--spacing-xs);
    }
    
    .btn-large {
        font-size: var(--font-size-xs);
        padding: 8px 20px;
    }
    
    /* Compress canvas padding for landscape */
    canvas {
        max-height: 85vh;
    }
}

/* Additional landscape optimization for very small heights */
@media screen and (orientation: landscape) and (max-height: 500px) {
    .ui-layer {
        padding: 4px var(--spacing-xs);
    }
    
    .level-display,
    .moves-needed-display {
        height: 32px;
        font-size: 0.65rem;
        padding: 0 6px;
    }
    
    .moves-needed-display {
        min-width: 65px;
        font-size: 0.55rem;
    }
    
    .btn-icon {
        width: 32px;
        height: 32px;
        min-width: 32px;
        min-height: 32px;
    }
    
    .btn-icon svg {
        width: 18px;
        height: 18px;
    }
    
    .start-modal,
    .instructions-modal {
        max-height: 95vh;
        padding: var(--spacing-xs);
    }
    
    .logo-title {
        font-size: var(--font-size-base);
        margin-bottom: 4px;
    }
    
    .logo-subtitle {
        font-size: 0.65rem;
    }
    
    .win-title,
    .game-over-title {
        font-size: var(--font-size-lg);
    }
}

/* High DPI displays */
@media (-webkit-min-device-pixel-ratio: 2), (min-resolution: 192dpi) {
    canvas {
        image-rendering: -webkit-optimize-contrast;
        image-rendering: crisp-edges;
    }
}

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