/* ============================================
   FLAPPY BIRD PREMIUM - COMPLETE CSS
   Clean, Organized, and Scalable Design System
   ============================================ */

/* ============================================
   1. CSS VARIABLES - Design Tokens
   ============================================ */
:root {
    /* Color Palette - Day Theme */
    --color-primary: hsl(200, 100%, 50%);
    --color-primary-dark: hsl(200, 100%, 40%);
    --color-secondary: hsl(45, 100%, 55%);
    --color-accent: hsl(320, 100%, 60%);
    --color-success: hsl(140, 70%, 50%);
    --color-danger: hsl(0, 80%, 60%);

    /* Background Colors */
    --color-bg-start: hsl(200, 80%, 85%);
    --color-bg-end: hsl(200, 90%, 95%);
    --color-ground: hsl(120, 40%, 35%);

    /* Text Colors */
    --color-text-primary: hsl(220, 20%, 10%);
    --color-text-secondary: hsl(220, 15%, 30%);
    --color-text-light: hsl(0, 0%, 100%);

    /* Shadows & Effects */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.15);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.2);
    --shadow-glow: 0 0 20px rgba(59, 130, 246, 0.5);

    /* Typography */
    --font-primary: 'Outfit', sans-serif;
    --font-secondary: 'Inter', sans-serif;

    /* Spacing Scale */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    --spacing-2xl: 48px;

    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --radius-full: 9999px;

    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-normal: 250ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 400ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* Theme Variations */
body.theme-night {
    --color-bg-start: hsl(230, 30%, 15%);
    --color-bg-end: hsl(230, 40%, 8%);
    --color-ground: hsl(220, 20%, 12%);
    --color-text-primary: hsl(0, 0%, 95%);
    --color-text-secondary: hsl(0, 0%, 70%);
}

body.theme-sunset {
    --color-bg-start: hsl(20, 80%, 60%);
    --color-bg-end: hsl(280, 60%, 40%);
    --color-ground: hsl(30, 50%, 25%);
}

body.theme-neon {
    --color-bg-start: hsl(280, 100%, 10%);
    --color-bg-end: hsl(200, 100%, 5%);
    --color-primary: hsl(300, 100%, 60%);
    --color-secondary: hsl(180, 100%, 50%);
    --color-accent: hsl(60, 100%, 50%);
    --color-ground: hsl(280, 50%, 8%);
}

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

body {
    font-family: var(--font-secondary);
    background: linear-gradient(180deg, var(--color-bg-start) 0%, var(--color-bg-end) 100%);
    color: var(--color-text-primary);
    overflow: hidden;
    width: 100vw;
    height: 100vh;
    transition: background var(--transition-slow);
}

/* ============================================
   3. GAME CONTAINER & CANVAS
   ============================================ */
.game-container {
    position: relative;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.background-layers {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
}

#gameCanvas {
    position: relative;
    z-index: 1;
    box-shadow: var(--shadow-lg);
    border-radius: var(--radius-sm);
}

/* ============================================
   4. OVERLAY SYSTEM (Menus & Dialogs)
   ============================================ */
.overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: none;
    align-items: center;
    justify-content: center;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(10px);
    z-index: 100;
}

.overlay.active {
    display: flex;
}

/* Menu Content - RESPONSIVE */
.menu-content {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.1), rgba(255, 255, 255, 0.05));
    backdrop-filter: blur(20px);
    border: 2px solid rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-xl);
    padding: var(--spacing-lg) var(--spacing-2xl);
    max-width: 600px;
    width: 90%;
    max-height: 95vh;
    overflow-y: auto;
    box-shadow: var(--shadow-lg);
    animation: slideInUp 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(50px) scale(0.9);
    }

    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

/* ============================================
   5. MENU - Title & Branding
   ============================================ */
.game-title {
    text-align: center;
    margin-bottom: var(--spacing-md);
    font-family: var(--font-primary);
    font-weight: 800;
    line-height: 0.9;
}

.title-flappy {
    display: block;
    font-size: clamp(2.5rem, 7vw, 4.5rem);
    background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-shadow: 0 4px 20px rgba(59, 130, 246, 0.5);
    animation: float 3s ease-in-out infinite;
}

.title-bird {
    display: block;
    font-size: clamp(2.5rem, 7vw, 4.5rem);
    background: linear-gradient(135deg, var(--color-secondary), var(--color-danger));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    animation: float 3s ease-in-out infinite 0.3s;
}

.title-premium {
    display: block;
    font-size: clamp(0.875rem, 1.8vw, 1.25rem);
    letter-spacing: 0.3em;
    color: var(--color-accent);
    text-shadow: 0 0 10px var(--color-accent);
    margin-top: var(--spacing-xs);
}

@keyframes float {

    0%,
    100% {
        transform: translateY(0px);
    }

    50% {
        transform: translateY(-10px);
    }
}

/* ============================================
   6. MENU - High Score Display
   ============================================ */
.high-score-display {
    text-align: center;
    margin-bottom: var(--spacing-lg);
    padding: var(--spacing-md);
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.score-label {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: var(--spacing-xs);
}

.score-value {
    font-size: 2.5rem;
    font-weight: 800;
    font-family: var(--font-primary);
    background: linear-gradient(135deg, var(--color-secondary), var(--color-accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* ============================================
   7. MENU - Mode Selector
   ============================================ */
.mode-selector {
    margin-bottom: var(--spacing-lg);
}

.mode-selector h3 {
    text-align: center;
    margin-bottom: var(--spacing-md);
    font-family: var(--font-primary);
    font-size: 1.25rem;
    color: var(--color-text-light);
}

.mode-buttons {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-md);
}

.mode-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: var(--spacing-md);
    background: rgba(255, 255, 255, 0.05);
    border: 2px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-normal);
    font-family: var(--font-secondary);
    color: var(--color-text-light);
    position: relative;
    overflow: hidden;
}

.mode-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
    opacity: 0;
    transition: opacity var(--transition-normal);
}

.mode-btn:hover::before {
    opacity: 0.1;
}

.mode-btn.active {
    border-color: var(--color-primary);
    background: rgba(59, 130, 246, 0.2);
    box-shadow: 0 0 20px rgba(59, 130, 246, 0.3);
}

.mode-btn.active::before {
    opacity: 0.15;
}

.mode-icon {
    font-size: 2rem;
    margin-bottom: var(--spacing-sm);
    position: relative;
    z-index: 1;
}

.mode-name {
    font-weight: 700;
    font-size: 1rem;
    margin-bottom: var(--spacing-xs);
    position: relative;
    z-index: 1;
}

.mode-desc {
    font-size: 0.75rem;
    color: var(--color-text-secondary);
    text-align: center;
    position: relative;
    z-index: 1;
}

/* ============================================
   8. MENU - Start Button
   ============================================ */
.start-btn {
    position: relative;
    width: 100%;
    padding: var(--spacing-lg);
    font-size: 1.5rem;
    font-weight: 700;
    font-family: var(--font-primary);
    color: var(--color-text-light);
    background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
    border: none;
    border-radius: var(--radius-full);
    cursor: pointer;
    overflow: hidden;
    transition: all var(--transition-normal);
    box-shadow: 0 4px 20px rgba(59, 130, 246, 0.4);
    margin-bottom: var(--spacing-lg);
}

.start-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(59, 130, 246, 0.6);
}

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

.btn-glow {
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    animation: btnGlow 3s infinite;
}

@keyframes btnGlow {
    0% {
        left: -100%;
    }

    100% {
        left: 100%;
    }
}

/* ============================================
   9. MENU - Footer Icons
   ============================================ */
.menu-footer {
    display: flex;
    justify-content: space-around;
    gap: var(--spacing-sm);
}

.icon-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm);
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-normal);
    font-size: 1.5rem;
    color: var(--color-text-light);
    flex: 1;
}

.icon-btn:hover {
    background: rgba(255, 255, 255, 0.1);
    transform: translateY(-2px);
}

.btn-label {
    font-size: 0.75rem;
    font-family: var(--font-secondary);
}

/* ============================================
   10. GAME OVER OVERLAY
   ============================================ */
.gameover-content {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.1), rgba(255, 255, 255, 0.05));
    backdrop-filter: blur(20px);
    border: 2px solid rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-xl);
    padding: var(--spacing-2xl);
    max-width: 500px;
    width: 90%;
    box-shadow: var(--shadow-lg);
    animation: slideInUp 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.gameover-title {
    text-align: center;
    font-family: var(--font-primary);
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: var(--spacing-xl);
    background: linear-gradient(135deg, var(--color-danger), var(--color-accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.score-panel {
    display: flex;
    justify-content: space-around;
    margin-bottom: var(--spacing-xl);
}

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

.new-record-badge {
    text-align: center;
    padding: var(--spacing-sm) var(--spacing-md);
    background: linear-gradient(135deg, var(--color-secondary), var(--color-accent));
    border-radius: var(--radius-full);
    margin-bottom: var(--spacing-lg);
    animation: pulse 1s infinite;
}

.new-record-badge.hidden {
    display: none;
}

@keyframes pulse {

    0%,
    100% {
        transform: scale(1);
    }

    50% {
        transform: scale(1.05);
    }
}

.badge-icon {
    font-size: 2rem;
    margin-right: var(--spacing-sm);
}

.badge-text {
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--color-text-light);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
}

.stat-item {
    text-align: center;
    padding: var(--spacing-md);
    background: rgba(255, 255, 255, 0.05);
    border-radius: var(--radius-md);
}

.stat-label {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-xs);
}

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

.gameover-buttons {
    display: flex;
    gap: var(--spacing-md);
}

.retry-btn,
.menu-btn {
    flex: 1;
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: 1.125rem;
    font-weight: 600;
    border: none;
    border-radius: var(--radius-full);
    cursor: pointer;
    transition: all var(--transition-normal);
}

.retry-btn {
    background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
    color: var(--color-text-light);
    box-shadow: 0 4px 16px rgba(59, 130, 246, 0.4);
}

.retry-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(59, 130, 246, 0.6);
}

.menu-btn {
    background: rgba(255, 255, 255, 0.1);
    color: var(--color-text-light);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.menu-btn:hover {
    background: rgba(255, 255, 255, 0.15);
}

/* ============================================
   11. PAUSE OVERLAY
   ============================================ */
.pause-content {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.1), rgba(255, 255, 255, 0.05));
    backdrop-filter: blur(20px);
    border: 2px solid rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-xl);
    padding: var(--spacing-2xl);
    text-align: center;
    min-width: 300px;
}

.pause-title {
    font-family: var(--font-primary);
    font-size: 2rem;
    margin-bottom: var(--spacing-xl);
    color: var(--color-text-light);
}

.resume-btn {
    width: 100%;
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    font-size: 1.125rem;
    font-weight: 600;
    background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
    color: var(--color-text-light);
    border: none;
    border-radius: var(--radius-full);
    cursor: pointer;
    transition: all var(--transition-normal);
}

.resume-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(59, 130, 246, 0.6);
}

/* ============================================
   12. MODALS (Skins, Achievements, Stats)
   ============================================ */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: none;
    align-items: center;
    justify-content: center;
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(10px);
    z-index: 150;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.1), rgba(255, 255, 255, 0.05));
    backdrop-filter: blur(20px);
    border: 2px solid rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-xl);
    padding: var(--spacing-2xl);
    max-width: 700px;
    width: 90%;
    max-height: 80vh;
    overflow-y: auto;
    box-shadow: var(--shadow-lg);
    animation: slideInUp 0.3s ease-out;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.modal-header h2 {
    font-family: var(--font-primary);
    font-size: 1.75rem;
    color: var(--color-text-light);
}

.close-btn {
    background: none;
    border: none;
    font-size: 2rem;
    color: var(--color-text-light);
    cursor: pointer;
    transition: all var(--transition-fast);
    line-height: 1;
    padding: 0;
    width: 32px;
    height: 32px;
}

.close-btn:hover {
    color: var(--color-danger);
    transform: rotate(90deg);
}

/* Skins Grid */
.skins-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    gap: var(--spacing-md);
}

.skin-item {
    padding: var(--spacing-lg);
    background: rgba(255, 255, 255, 0.05);
    border: 2px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-normal);
    text-align: center;
}

.skin-item:hover {
    background: rgba(255, 255, 255, 0.1);
    transform: translateY(-4px);
}

.skin-item.active {
    border-color: var(--color-primary);
    background: rgba(59, 130, 246, 0.2);
    box-shadow: 0 0 20px rgba(59, 130, 246, 0.4);
}

.skin-item.locked {
    opacity: 0.5;
    cursor: not-allowed;
}

.skin-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-sm);
}

.skin-name {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-text-light);
}

.skin-requirement {
    font-size: 0.75rem;
    color: var(--color-text-secondary);
    margin-top: var(--spacing-xs);
}

/* Achievements List */
.achievements-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.achievement-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    transition: all var(--transition-normal);
}

.achievement-item.unlocked {
    border-color: var(--color-success);
    background: rgba(34, 197, 94, 0.1);
}

.achievement-icon {
    font-size: 2.5rem;
    filter: grayscale(100%);
    opacity: 0.5;
}

.achievement-item.unlocked .achievement-icon {
    filter: grayscale(0%);
    opacity: 1;
    animation: bounce 0.5s ease;
}

@keyframes bounce {

    0%,
    100% {
        transform: translateY(0);
    }

    50% {
        transform: translateY(-10px);
    }
}

.achievement-info {
    flex: 1;
}

.achievement-name {
    font-weight: 700;
    font-size: 1rem;
    color: var(--color-text-light);
    margin-bottom: var(--spacing-xs);
}

.achievement-desc {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
}

.achievement-progress {
    font-size: 0.75rem;
    color: var(--color-primary);
    margin-top: var(--spacing-xs);
}

/* Stats Container */
.stats-container {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-lg);
}

.stat-card {
    padding: var(--spacing-lg);
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    text-align: center;
}

.stat-card-value {
    font-size: 2.5rem;
    font-weight: 800;
    font-family: var(--font-primary);
    background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-sm);
}

.stat-card-label {
    font-size: 1rem;
    color: var(--color-text-secondary);
}

/* ============================================
   13. IN-GAME UI
   ============================================ */
.game-ui {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 5;
}

.game-ui.hidden {
    display: none;
}

.top-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-lg);
}

.current-score {
    font-size: 3rem;
    font-weight: 800;
    font-family: var(--font-primary);
    color: var(--color-text-light);
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.5),
        0 0 20px rgba(255, 255, 255, 0.3);
}

.game-mode-indicator {
    padding: var(--spacing-sm) var(--spacing-md);
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-full);
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-text-light);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.pause-btn {
    pointer-events: all;
    width: 48px;
    height: 48px;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-md);
    font-size: 1.5rem;
    color: var(--color-text-light);
    cursor: pointer;
    transition: all var(--transition-normal);
}

.pause-btn:hover {
    background: rgba(0, 0, 0, 0.7);
    transform: scale(1.1);
}

/* Power-up Bar */
.powerup-bar {
    position: absolute;
    bottom: var(--spacing-lg);
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: var(--spacing-sm);
}

.powerup-indicator {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(10px);
    border: 2px solid;
    border-radius: var(--radius-full);
    color: var(--color-text-light);
    font-size: 0.875rem;
    font-weight: 600;
    animation: powerupPulse 1s infinite;
}

@keyframes powerupPulse {

    0%,
    100% {
        transform: scale(1);
    }

    50% {
        transform: scale(1.05);
    }
}

.powerup-indicator.shield {
    border-color: var(--color-primary);
    box-shadow: 0 0 20px rgba(59, 130, 246, 0.5);
}

.powerup-indicator.slowmo {
    border-color: var(--color-accent);
    box-shadow: 0 0 20px rgba(236, 72, 153, 0.5);
}

.powerup-indicator.doublepoints {
    border-color: var(--color-secondary);
    box-shadow: 0 0 20px rgba(251, 191, 36, 0.5);
}

.powerup-indicator.magnet {
    border-color: var(--color-success);
    box-shadow: 0 0 20px rgba(34, 197, 94, 0.5);
}

.powerup-icon {
    font-size: 1.25rem;
}

/* Timer Display */
.timer-display {
    position: absolute;
    top: var(--spacing-lg);
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(10px);
    border: 2px solid var(--color-accent);
    border-radius: var(--radius-full);
    box-shadow: 0 0 20px rgba(236, 72, 153, 0.5);
}

.timer-display.hidden {
    display: none;
}

.timer-label {
    font-size: 1rem;
    font-weight: 600;
    color: var(--color-text-light);
}

.timer-value {
    font-size: 1.5rem;
    font-weight: 800;
    font-family: var(--font-primary);
    color: var(--color-accent);
}

/* ============================================
   14. ACHIEVEMENT NOTIFICATION
   ============================================ */
.achievement-notification {
    position: absolute;
    top: var(--spacing-xl);
    right: var(--spacing-xl);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md) var(--spacing-lg);
    background: linear-gradient(135deg, rgba(34, 197, 94, 0.9), rgba(16, 185, 129, 0.9));
    backdrop-filter: blur(10px);
    border: 2px solid var(--color-success);
    border-radius: var(--radius-md);
    box-shadow: 0 4px 20px rgba(34, 197, 94, 0.5);
    z-index: 200;
    animation: slideInRight 0.5s ease-out;
    max-width: 350px;
}

.achievement-notification.hidden {
    display: none;
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(400px);
    }

    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.notification-icon {
    font-size: 2.5rem;
}

.notification-content {
    flex: 1;
}

.notification-title {
    font-weight: 700;
    font-size: 1.125rem;
    color: var(--color-text-light);
    margin-bottom: var(--spacing-xs);
}

.notification-text {
    font-size: 0.875rem;
    color: rgba(255, 255, 255, 0.9);
}

/* ============================================
   15. SCROLLBAR CUSTOMIZATION
   ============================================ */
.menu-content::-webkit-scrollbar,
.modal-content::-webkit-scrollbar {
    width: 8px;
}

.menu-content::-webkit-scrollbar-track,
.modal-content::-webkit-scrollbar-track {
    background: rgba(255, 255, 255, 0.05);
    border-radius: var(--radius-sm);
}

.menu-content::-webkit-scrollbar-thumb,
.modal-content::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-sm);
}

.menu-content::-webkit-scrollbar-thumb:hover,
.modal-content::-webkit-scrollbar-thumb:hover {
    background: rgba(255, 255, 255, 0.3);
}

/* ============================================
   16. RESPONSIVE DESIGN
   ============================================ */

/* Medium Screens (Tablets) */
@media (max-width: 768px) {
    .menu-content {
        padding: var(--spacing-md) var(--spacing-lg);
        width: 95%;
    }

    .title-flappy,
    .title-bird {
        font-size: clamp(2rem, 6vw, 3.5rem);
    }

    .title-premium {
        font-size: clamp(0.75rem, 1.5vw, 1rem);
    }

    .mode-selector h3 {
        font-size: 1.125rem;
    }

    .start-btn {
        font-size: 1.25rem;
        padding: var(--spacing-md);
    }

    .menu-footer {
        flex-wrap: wrap;
    }

    .icon-btn {
        flex: 1 1 calc(50% - var(--spacing-sm));
    }

    .current-score {
        font-size: 2.5rem;
    }

    .stats-container {
        grid-template-columns: 1fr;
    }
}

/* Small Screens & Short Heights */
@media (max-height: 700px) {
    .menu-content {
        padding: var(--spacing-sm) var(--spacing-md);
        max-height: 98vh;
    }

    .game-title {
        margin-bottom: var(--spacing-sm);
    }

    .high-score-display {
        margin-bottom: var(--spacing-md);
        padding: var(--spacing-sm);
    }

    .mode-selector {
        margin-bottom: var(--spacing-md);
    }

    .start-btn {
        padding: var(--spacing-md);
        margin-bottom: var(--spacing-md);
    }
}

/* Very Small Screens */
@media (max-width: 480px) {
    .mode-buttons {
        grid-template-columns: 1fr;
    }

    .score-panel {
        flex-direction: column;
        gap: var(--spacing-md);
    }

    .stats-grid {
        grid-template-columns: 1fr;
    }

    .skins-grid {
        grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
    }
}

/* Landscape Orientation on Mobile */
@media (max-height: 600px) and (orientation: landscape) {
    .menu-content {
        padding: var(--spacing-xs) var(--spacing-md);
        max-height: 95vh;
    }

    .title-flappy,
    .title-bird {
        font-size: clamp(1.5rem, 5vw, 2.5rem);
    }

    .high-score-display {
        padding: var(--spacing-xs) var(--spacing-sm);
        margin-bottom: var(--spacing-sm);
    }

    .mode-buttons {
        gap: var(--spacing-sm);
    }

    .mode-btn {
        padding: var(--spacing-sm);
    }

    .mode-icon {
        font-size: 1.5rem;
    }
}

/* ============================================
   17. UTILITY CLASSES
   ============================================ */
.hidden {
    display: none !important;
}

.visible {
    display: block !important;
}

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

/* END OF STYLES */