/* ==========================================================================
   Violet's Phonics Blend Lab & Playground - Modern Design System
   ========================================================================== */

:root {
    --primary: #7928ca;
    --primary-light: #9b51e0;
    --primary-dark: #581c87;
    --accent: #ff0080;
    --accent-gold: #ffb800;
    --accent-gold-dark: #d97706;
    --bg-gradient: linear-gradient(135deg, #f5f0ff 0%, #eadaff 40%, #ffd8f0 100%);
    --card-bg: rgba(255, 255, 255, 0.92);
    --glass-border: rgba(255, 255, 255, 0.6);
    --glass-shadow: 0 12px 36px -6px rgba(121, 40, 202, 0.15), 0 4px 12px rgba(0, 0, 0, 0.05);
    --text-main: #2d1847;
    --text-muted: #6b5c7e;
    --radius-lg: 28px;
    --radius-md: 18px;
    --radius-sm: 10px;
    --font-heading: 'Fredoka', 'Outfit', -apple-system, sans-serif;
    --font-body: 'Outfit', -apple-system, sans-serif;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    -webkit-tap-highlight-color: transparent;
    user-select: none;
}

body {
    min-height: 100vh;
    font-family: var(--font-body);
    color: var(--text-main);
    background: var(--bg-gradient);
    background-attachment: fixed;
    display: flex;
    flex-direction: column;
    overflow-x: hidden;
}

/* --------------------------------------------------------------------------
   Top Navigation & Header
   -------------------------------------------------------------------------- */
.app-header {
    background: rgba(255, 255, 255, 0.75);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 2px solid rgba(255, 255, 255, 0.8);
    position: sticky;
    top: 0;
    z-index: 100;
    padding: 10px 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 4px 20px rgba(121, 40, 202, 0.08);
}

.brand-section {
    display: flex;
    align-items: center;
    gap: 12px;
}

.brand-mascot {
    font-size: 2rem;
    animation: gentleWiggle 4s ease-in-out infinite;
}

.brand-title {
    font-family: var(--font-heading);
    font-size: 1.4rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary) 0%, var(--accent) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -0.5px;
}

.mode-switcher {
    display: flex;
    background: rgba(234, 218, 255, 0.6);
    padding: 4px;
    border-radius: 999px;
    border: 1px solid rgba(255, 255, 255, 0.7);
}

.mode-btn {
    font-family: var(--font-heading);
    font-size: 1rem;
    font-weight: 600;
    padding: 8px 18px;
    border-radius: 999px;
    border: none;
    background: transparent;
    color: var(--text-muted);
    cursor: pointer;
    transition: all 0.25s cubic-bezier(0.34, 1.56, 0.64, 1);
    display: flex;
    align-items: center;
    gap: 6px;
}

.mode-btn:hover {
    color: var(--primary);
}

.mode-btn.active {
    background: #ffffff;
    color: var(--primary);
    box-shadow: 0 4px 12px rgba(121, 40, 202, 0.18);
    transform: scale(1.02);
}

.header-right {
    display: flex;
    align-items: center;
    gap: 12px;
}

/* Star Bank Pill */
.star-bank-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    background: linear-gradient(135deg, #fff9e6 0%, #fff0b3 100%);
    border: 2px solid var(--accent-gold);
    border-radius: 999px;
    padding: 6px 14px;
    cursor: pointer;
    box-shadow: 0 4px 14px rgba(255, 184, 0, 0.25);
    transition: transform 0.2s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.star-bank-btn:hover {
    transform: translateY(-2px) scale(1.04);
}

.star-bank-btn:active {
    transform: translateY(1px) scale(0.98);
}

.star-count {
    font-family: var(--font-heading);
    font-size: 1.15rem;
    font-weight: 700;
    color: #92400e;
}

.header-progress-wrap {
    width: 60px;
    height: 8px;
    background: rgba(0, 0, 0, 0.08);
    border-radius: 999px;
    overflow: hidden;
}

.header-progress-fill {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, #ffb800, #ff69b4);
    border-radius: 999px;
    transition: width 0.4s ease-out;
}

.icon-btn {
    font-family: var(--font-heading);
    font-size: 0.95rem;
    font-weight: 700;
    background: rgba(255, 255, 255, 0.8);
    border: 1.5px solid rgba(121, 40, 202, 0.2);
    border-radius: 999px;
    padding: 6px 12px;
    color: var(--primary);
    cursor: pointer;
    transition: all 0.2s ease;
    min-height: 38px;
    min-width: 38px;
}

.icon-btn:hover {
    background: #ffffff;
    border-color: var(--primary);
    transform: scale(1.05);
}

/* --------------------------------------------------------------------------
   Main Content Layout
   -------------------------------------------------------------------------- */
.main-viewport {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 24px 16px;
    position: relative;
}

/* Views */
.game-view {
    display: none !important;
    width: 100%;
    margin: 0 auto;
}

.game-view.active {
    display: flex !important;
}

#phonicsView.game-view.active {
    max-width: 900px;
    flex-direction: column;
    align-items: center;
}

#runnerView.game-view.active {
    max-width: 1040px;
    width: 100%;
    flex-direction: column;
    align-items: center;
}

/* --------------------------------------------------------------------------
   Phonics Arena
   -------------------------------------------------------------------------- */
.phonics-arena {
    width: 100%;
    background: var(--card-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 2px solid var(--glass-border);
    border-radius: var(--radius-lg);
    box-shadow: var(--glass-shadow);
    padding: 36px 28px;
    display: flex;
    flex-direction: column;
    align-items: center;
    position: relative;
    overflow: hidden;
}

.arena-top-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
    margin-bottom: 24px;
}

.word-category-badge {
    font-family: var(--font-heading);
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--primary);
    background: rgba(121, 40, 202, 0.08);
    border: 1.5px solid rgba(121, 40, 202, 0.2);
    padding: 6px 16px;
    border-radius: 999px;
}

.sound-instruction {
    font-family: var(--font-body);
    font-size: 1rem;
    color: var(--text-muted);
}

/* --------------------------------------------------------------------------
   Tactile 3D Sound Boxes
   -------------------------------------------------------------------------- */
.sound-boxes-container {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 20px;
    margin: 32px 0 20px;
    width: 100%;
    flex-wrap: wrap;
    transition: opacity 0.3s ease, transform 0.3s ease;
}

.sound-boxes-container.fade-slide-out {
    opacity: 0;
    transform: translateY(-20px) scale(0.95);
}

.sound-box-card {
    width: 120px;
    height: 140px;
    background: #ffffff;
    border: 3px solid #7928ca;
    border-bottom: 9px solid #581c87;
    border-radius: 24px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    box-shadow: 0 10px 24px rgba(121, 40, 202, 0.12);
    position: relative;
    transition: transform 0.12s cubic-bezier(0.34, 1.56, 0.64, 1),
                border-color 0.2s ease,
                box-shadow 0.2s ease;
}

.sound-box-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 16px 28px rgba(121, 40, 202, 0.2);
}

.sound-box-card:active {
    transform: translateY(6px);
    border-bottom-width: 3px;
    box-shadow: 0 4px 8px rgba(121, 40, 202, 0.1);
}

.box-letter {
    font-family: var(--font-heading);
    font-size: 5rem;
    line-height: 1;
    font-weight: 700;
    color: #2d1847;
}

.box-tap-hint {
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: #9b51e0;
    margin-top: 4px;
    opacity: 0.7;
}

/* Animations on letter boxes */
.sound-box-card.pop-anim {
    animation: cardPop 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.sound-box-card.active-glow {
    border-color: var(--accent);
    border-bottom-color: #c20063;
    box-shadow: 0 0 25px rgba(255, 0, 128, 0.4);
}

.sound-box-card.sweep-pulse {
    transform: translateY(-8px) scale(1.08);
    border-color: var(--accent-gold);
    border-bottom-color: var(--accent-gold-dark);
    box-shadow: 0 0 30px rgba(255, 184, 0, 0.6);
}

.sound-box-card.blended-word-pop {
    animation: blendCelebration 0.6s cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* --------------------------------------------------------------------------
   Blend Sweep Track & Indicator
   -------------------------------------------------------------------------- */
.sweep-track-container {
    width: 80%;
    max-width: 480px;
    height: 14px;
    background: rgba(121, 40, 202, 0.1);
    border-radius: 999px;
    margin: 12px 0 36px;
    position: relative;
    overflow: visible;
}

.sweep-indicator {
    position: absolute;
    top: -12px;
    left: 0;
    width: 40px;
    height: 40px;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.8rem;
    opacity: 0;
    pointer-events: none;
    transform: translateX(0%);
    filter: drop-shadow(0 4px 10px rgba(255, 184, 0, 0.6));
}

/* --------------------------------------------------------------------------
   Action Buttons
   -------------------------------------------------------------------------- */
.arena-actions {
    display: flex;
    align-items: center;
    gap: 18px;
    flex-wrap: wrap;
    justify-content: center;
}

.btn-game-primary {
    font-family: var(--font-heading);
    font-size: 1.4rem;
    font-weight: 700;
    padding: 16px 36px;
    border-radius: 999px;
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 10px;
    box-shadow: 0 8px 24px rgba(121, 40, 202, 0.25);
    transition: transform 0.15s cubic-bezier(0.34, 1.56, 0.64, 1), box-shadow 0.2s ease;
}

.btn-game-primary:hover {
    transform: translateY(-3px) scale(1.03);
    box-shadow: 0 12px 30px rgba(121, 40, 202, 0.35);
}

.btn-game-primary:active {
    transform: translateY(2px) scale(0.97);
}

.btn-blend {
    background: linear-gradient(135deg, #7928ca 0%, #ff0080 100%);
    color: #ffffff;
}

.btn-read-it {
    background: linear-gradient(135deg, #ffb800 0%, #ff8c00 100%);
    color: #5d2500;
    border: 2px solid #ffffff;
    box-shadow: 0 8px 24px rgba(255, 184, 0, 0.35);
}

.btn-read-it.ready-pulse {
    animation: goldPulse 1.4s infinite;
}

.btn-skip {
    font-family: var(--font-heading);
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text-muted);
    background: transparent;
    border: 2px solid rgba(121, 40, 202, 0.15);
    padding: 14px 24px;
    border-radius: 999px;
    cursor: pointer;
    transition: all 0.2s ease;
}

.btn-skip:hover {
    background: rgba(121, 40, 202, 0.05);
    color: var(--primary);
    border-color: var(--primary);
}

/* --------------------------------------------------------------------------
   Runner View Container
   -------------------------------------------------------------------------- */
#runnerView {
    background: #87CEEB;
    border-radius: var(--radius-lg);
    box-shadow: var(--glass-shadow);
    overflow: hidden;
    position: relative;
    border: 4px solid rgba(255, 255, 255, 0.9);
    width: 100%;
    max-width: 1000px;
    height: 600px;
    max-height: 72vh;
}

.runner-frame {
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
}

#runnerCanvas {
    width: 100% !important;
    height: 100% !important;
    display: block !important;
    object-fit: contain;
}

.runner-controls-hint {
    position: absolute;
    bottom: 12px;
    left: 50%;
    transform: translateX(-50%);
    background: rgba(0, 0, 0, 0.55);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    color: #ffffff;
    padding: 6px 18px;
    border-radius: 999px;
    font-size: 0.85rem;
    font-weight: 600;
    pointer-events: none;
    z-index: 10;
    white-space: nowrap;
}

.runner-start-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(135, 206, 235, 0.95);
    backdrop-filter: blur(6px);
    -webkit-backdrop-filter: blur(6px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 20;
    transition: opacity 0.25s ease;
}

.runner-start-overlay.hidden {
    display: none !important;
}

.runner-splash-card {
    background: rgba(255, 255, 255, 0.96);
    border: 3px solid #ff4d6d;
    border-radius: var(--radius-lg);
    padding: 32px 36px;
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    box-shadow: 0 16px 40px rgba(255, 77, 109, 0.22);
    max-width: 440px;
    width: 90%;
}

.runner-splash-icon {
    font-size: 3.5rem;
    animation: gentleWiggle 3s ease-in-out infinite;
    margin-bottom: 6px;
}

.runner-splash-title {
    font-family: var(--font-heading);
    font-size: 1.8rem;
    color: #c9184a;
    margin-bottom: 6px;
}

.runner-splash-desc {
    color: var(--text-muted);
    font-size: 0.95rem;
    margin-bottom: 16px;
}

.runner-splash-controls {
    display: flex;
    flex-direction: column;
    gap: 6px;
    font-size: 0.85rem;
    font-weight: 600;
    color: #590d22;
    background: #fff0f3;
    padding: 10px 18px;
    border-radius: var(--radius-md);
    margin-bottom: 20px;
    width: 100%;
}

.btn-start-runner {
    font-family: var(--font-heading);
    font-size: 1.3rem;
    font-weight: 700;
    background: linear-gradient(135deg, #ff4d6d 0%, #c9184a 100%);
    color: #ffffff;
    border: none;
    padding: 14px 34px;
    border-radius: 999px;
    cursor: pointer;
    box-shadow: 0 8px 24px rgba(201, 24, 74, 0.35);
    display: flex;
    align-items: center;
    gap: 10px;
    transition: transform 0.15s cubic-bezier(0.34, 1.56, 0.64, 1), box-shadow 0.2s ease;
}

.btn-start-runner:hover {
    transform: translateY(-3px) scale(1.04);
    box-shadow: 0 12px 30px rgba(201, 24, 74, 0.45);
}

.btn-start-runner:active {
    transform: translateY(2px) scale(0.97);
}

/* --------------------------------------------------------------------------
   Goal Modal (Kid Facing)
   -------------------------------------------------------------------------- */
.modal-backdrop {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(45, 24, 71, 0.6);
    backdrop-filter: blur(8px);
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 200;
}

.modal-backdrop.active {
    display: flex;
}

.goal-card {
    background: #ffffff;
    border-radius: var(--radius-lg);
    padding: 36px 32px;
    width: 90%;
    max-width: 440px;
    text-align: center;
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.2);
    position: relative;
    border: 3px solid #ffb800;
}

.goal-badge {
    font-size: 3rem;
    margin-bottom: 12px;
}

.goal-title {
    font-family: var(--font-heading);
    font-size: 1.6rem;
    color: var(--text-main);
    margin-bottom: 8px;
}

.goal-count {
    font-family: var(--font-heading);
    font-size: 1.3rem;
    font-weight: 700;
    color: #d97706;
    margin-bottom: 18px;
}

.goal-bar-wrap {
    width: 100%;
    height: 18px;
    background: #fef3c7;
    border-radius: 999px;
    overflow: hidden;
    margin-bottom: 24px;
    border: 1px solid #fde68a;
}

.goal-bar-fill {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, #ffb800, #ff69b4);
    border-radius: 999px;
    transition: width 0.5s ease;
}

.btn-close-modal {
    font-family: var(--font-heading);
    font-size: 1.1rem;
    font-weight: 700;
    background: var(--primary);
    color: #ffffff;
    border: none;
    padding: 12px 28px;
    border-radius: 999px;
    cursor: pointer;
}

/* --------------------------------------------------------------------------
   Parent Admin Modal
   -------------------------------------------------------------------------- */
.admin-modal-backdrop {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(18, 11, 28, 0.85);
    backdrop-filter: blur(12px);
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 300;
}

.admin-modal-backdrop.active {
    display: flex;
}

.admin-modal-card {
    background: #1c1427;
    color: #f3e8ff;
    border: 1px solid rgba(168, 85, 247, 0.3);
    border-radius: var(--radius-lg);
    width: 92%;
    max-width: 680px;
    max-height: 85vh;
    overflow-y: auto;
    padding: 30px;
    box-shadow: 0 25px 60px rgba(0, 0, 0, 0.6);
}

.admin-modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid rgba(168, 85, 247, 0.2);
    padding-bottom: 16px;
    margin-bottom: 20px;
}

.admin-modal-header h2 {
    font-family: var(--font-heading);
    font-size: 1.4rem;
    color: #e9d5ff;
}

.admin-close-btn {
    background: transparent;
    border: none;
    color: #c084fc;
    font-size: 2rem;
    cursor: pointer;
    line-height: 1;
}

.admin-tabs {
    display: flex;
    gap: 8px;
    margin-bottom: 24px;
    border-bottom: 1px solid rgba(168, 85, 247, 0.2);
    padding-bottom: 10px;
    flex-wrap: wrap;
}

.admin-tab {
    background: transparent;
    border: 1px solid rgba(168, 85, 247, 0.3);
    color: #c084fc;
    padding: 8px 16px;
    border-radius: 999px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 600;
    transition: all 0.2s ease;
}

.admin-tab.active {
    background: #9333ea;
    color: #ffffff;
    border-color: #9333ea;
}

.admin-tab-content {
    display: none;
}

.admin-tab-content.active {
    display: block;
}

.admin-stat-card {
    background: rgba(147, 51, 234, 0.15);
    border: 1px solid rgba(147, 51, 234, 0.3);
    border-radius: var(--radius-md);
    padding: 16px 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 1.2rem;
    margin-bottom: 20px;
}

.admin-stat-card strong {
    font-size: 1.6rem;
    color: #fbbf24;
}

.admin-section {
    margin-bottom: 24px;
}

.admin-section h3,
.admin-tab-content h3 {
    font-size: 1.05rem;
    color: #d8b4fe;
    margin-bottom: 12px;
}

.admin-row {
    display: flex;
    gap: 10px;
    margin-bottom: 12px;
    flex-wrap: wrap;
}

.admin-input {
    background: rgba(30, 20, 44, 0.8);
    border: 1px solid rgba(168, 85, 247, 0.4);
    color: #ffffff;
    padding: 10px 14px;
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    flex: 1;
    min-width: 140px;
}

.admin-input:focus {
    outline: none;
    border-color: #c084fc;
}

.admin-btn {
    padding: 10px 20px;
    border-radius: var(--radius-sm);
    border: none;
    font-weight: 600;
    cursor: pointer;
    transition: opacity 0.2s ease;
}

.admin-btn:hover {
    opacity: 0.9;
}

.admin-btn-primary {
    background: #9333ea;
    color: #ffffff;
}

.admin-btn-success {
    background: #059669;
    color: #ffffff;
}

.admin-btn-danger {
    background: #dc2626;
    color: #ffffff;
}

/* Ledger List */
.admin-ledger-list {
    max-height: 300px;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.admin-ledger-item {
    background: rgba(30, 20, 44, 0.7);
    border: 1px solid rgba(168, 85, 247, 0.2);
    border-radius: var(--radius-sm);
    padding: 10px 14px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.ledger-left {
    display: flex;
    flex-direction: column;
}

.ledger-reason {
    font-weight: 600;
    color: #e9d5ff;
}

.ledger-time {
    font-size: 0.75rem;
    color: #a855f7;
}

.ledger-right {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
}

.ledger-delta {
    font-weight: 700;
    font-size: 1rem;
}

.ledger-delta.delta-pos {
    color: #34d399;
}

.ledger-delta.delta-neg {
    color: #f87171;
}

.ledger-balance {
    font-size: 0.75rem;
    color: #a855f7;
}

.admin-empty {
    color: #a855f7;
    font-style: italic;
    padding: 20px;
    text-align: center;
}

.admin-categories-list {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.admin-checkbox-label {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 0.95rem;
    color: #e9d5ff;
    cursor: pointer;
}

.admin-chips-container {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    margin-top: 10px;
}

.admin-chip {
    background: rgba(147, 51, 234, 0.25);
    border: 1px solid rgba(168, 85, 247, 0.4);
    padding: 4px 10px;
    border-radius: 999px;
    font-size: 0.85rem;
    display: flex;
    align-items: center;
    gap: 6px;
}

.admin-chip-remove {
    background: transparent;
    border: none;
    color: #f87171;
    font-size: 1.1rem;
    cursor: pointer;
    line-height: 1;
}

.admin-form-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
    margin-bottom: 16px;
}

.admin-form-group label {
    font-size: 0.9rem;
    color: #c084fc;
}

/* --------------------------------------------------------------------------
   Confetti Canvas
   -------------------------------------------------------------------------- */
#confettiCanvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    pointer-events: none;
    z-index: 500;
}

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */
.app-footer {
    padding: 16px;
    text-align: center;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.footer-version {
    cursor: pointer;
    display: inline-block;
    padding: 2px 8px;
    border-radius: 4px;
}

/* --------------------------------------------------------------------------
   Keyframe Animations
   -------------------------------------------------------------------------- */
@keyframes cardPop {
    0% { transform: scale(1); }
    40% { transform: scale(0.92) translateY(6px); }
    70% { transform: scale(1.08) translateY(-6px); }
    100% { transform: scale(1) translateY(0); }
}

@keyframes blendCelebration {
    0% { transform: scale(1); }
    50% { transform: scale(1.06) translateY(-4px); }
    100% { transform: scale(1) translateY(0); }
}

@keyframes goldPulse {
    0% { box-shadow: 0 0 0 0 rgba(255, 184, 0, 0.7); transform: scale(1); }
    50% { box-shadow: 0 0 0 14px rgba(255, 184, 0, 0); transform: scale(1.03); }
    100% { box-shadow: 0 0 0 0 rgba(255, 184, 0, 0); transform: scale(1); }
}

@keyframes gentleWiggle {
    0%, 100% { transform: rotate(0deg); }
    25% { transform: rotate(-6deg); }
    75% { transform: rotate(6deg); }
}

/* --------------------------------------------------------------------------
   Responsive Breakpoints
   -------------------------------------------------------------------------- */
@media (max-width: 640px) {
    .app-header {
        flex-direction: column;
        gap: 12px;
        padding: 12px 14px;
    }

    .header-right {
        width: 100%;
        justify-content: space-between;
    }

    .sound-box-card {
        width: 85px;
        height: 105px;
        border-radius: 16px;
    }

    .box-letter {
        font-size: 3.5rem;
    }

    .btn-game-primary {
        font-size: 1.15rem;
        padding: 14px 26px;
        width: 100%;
        justify-content: center;
    }
}