/* ==========================================
   SmartVocab CSS Design System (Premium Glassmorphism)
   ========================================== */

:root {
    --bg-main: radial-gradient(ellipse at bottom, #111827 0%, #030712 100%);
    --bg-card: rgba(255, 255, 255, 0.03);
    --border-glass: 1px solid rgba(255, 255, 255, 0.08);
    --shadow-glass: 0 10px 40px 0 rgba(0, 0, 0, 0.4);
    --blur-glass: blur(14px);

    --text-primary: #f3f4f6;
    --text-secondary: #9ca3af;
    --text-muted: #6b7280;

    /* Theme colors */
    --color-primary: #8b5cf6; /* Vibrant violet */
    --color-primary-hover: #a78bfa;
    --color-accent: #06b6d4;  /* Neon cyan */
    
    /* Mastery States (High harmony, non-generic) */
    --color-unknown-text: #a1a1aa;
    --color-unknown-bg: rgba(161, 161, 170, 0.08);
    --color-unknown-border: rgba(161, 161, 170, 0.2);

    --color-l1-text: #fb7185; /* Soft rose-coral */
    --color-l1-bg: rgba(251, 113, 133, 0.1);
    --color-l1-border: rgba(251, 113, 133, 0.25);
    --color-l1-glow: rgba(251, 113, 133, 0.35);

    --color-l2-text: #fbbf24; /* Amber gold */
    --color-l2-bg: rgba(251, 191, 36, 0.1);
    --color-l2-border: rgba(251, 191, 36, 0.25);
    --color-l2-glow: rgba(251, 191, 36, 0.35);

    --color-l3-text: #34d399; /* Emerald green */
    --color-l3-bg: rgba(52, 211, 153, 0.1);
    --color-l3-border: rgba(52, 211, 153, 0.25);
    --color-l3-glow: rgba(52, 211, 153, 0.35);
}

/* Reset & Basics */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Outfit', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background: var(--bg-main);
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    overflow-x: hidden;
}

/* Scrollbar Customization */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}
::-webkit-scrollbar-track {
    background: rgba(0, 0, 0, 0.2);
}
::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.1);
    border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
    background: rgba(255, 255, 255, 0.25);
}

/* App Container */
.app-container {
    width: 100%;
    max-width: 960px;
    margin: 30px auto;
    padding: 0 20px;
    display: flex;
    flex-direction: column;
    gap: 24px;
}

/* Header & Navigation */
.app-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 18px 24px;
    background: var(--bg-card);
    border: var(--border-glass);
    backdrop-filter: var(--blur-glass);
    border-radius: 20px;
    box-shadow: var(--shadow-glass);
}

.logo-area {
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo-icon {
    font-size: 1.5rem;
    filter: drop-shadow(0 0 10px var(--color-primary));
}

.logo-area h1 {
    font-size: 1.4rem;
    font-weight: 700;
    background: linear-gradient(135deg, #fff 30%, #a78bfa 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -0.5px;
}

.badge-version {
    font-size: 0.75rem;
    background: rgba(139, 92, 246, 0.2);
    color: var(--color-primary-hover);
    padding: 2px 8px;
    border-radius: 8px;
    border: 1px solid rgba(139, 92, 246, 0.3);
    font-weight: 500;
}

.app-nav {
    display: flex;
    gap: 8px;
}

.nav-tab {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    padding: 10px 18px;
    border-radius: 12px;
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.nav-tab:hover {
    color: var(--text-primary);
    background: rgba(255, 255, 255, 0.05);
}

.nav-tab.active {
    color: var(--text-primary);
    background: rgba(139, 92, 246, 0.2);
    border: 1px solid rgba(139, 92, 246, 0.3);
    box-shadow: 0 0 15px rgba(139, 92, 246, 0.15);
}

.icon {
    width: 18px;
    height: 18px;
    fill: currentColor;
}

/* Stats Dashboard */
.stats-dashboard {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 16px;
}

.stat-card {
    background: var(--bg-card);
    border: var(--border-glass);
    backdrop-filter: var(--blur-glass);
    border-radius: 20px;
    padding: 16px;
    text-align: center;
    box-shadow: var(--shadow-glass);
    display: flex;
    flex-direction: column;
    justify-content: center;
    position: relative;
    overflow: hidden;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.stat-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: transparent;
}

.stat-card[data-type="all"]::before { background: var(--text-primary); }
.stat-card[data-type="unknown"]::before { background: var(--color-unknown-text); }
.stat-card[data-type="l1"]::before { background: var(--color-l1-text); }
.stat-card[data-type="l2"]::before { background: var(--color-l2-text); }
.stat-card[data-type="l3"]::before { background: var(--color-l3-text); }

.stat-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.5);
}

.stat-num {
    font-size: 1.8rem;
    font-weight: 700;
    line-height: 1.2;
    font-variant-numeric: tabular-nums;
}

.stat-label {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-top: 6px;
    font-weight: 500;
}

/* Specific Mastery Colors */
.color-unknown { color: var(--color-unknown-text); }
.color-l1 { color: var(--color-l1-text); text-shadow: 0 0 10px rgba(251, 113, 133, 0.1); }
.color-l2 { color: var(--color-l2-text); text-shadow: 0 0 10px rgba(251, 191, 36, 0.1); }
.color-l3 { color: var(--color-l3-text); text-shadow: 0 0 10px rgba(52, 211, 153, 0.1); }

/* Panels */
.panel-content {
    display: none;
    animation: fadeIn 0.4s ease-out;
}

.panel-content.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ==========================================
   1. CARD REVIEW MODE STYLING
   ========================================== */

.card-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
    max-width: 600px;
    margin: 0 auto;
}

/* Study Filter Bar */
.study-filter-bar {
    width: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--bg-card);
    border: var(--border-glass);
    border-radius: 16px;
    padding: 12px 20px;
}

.study-filter-bar label {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.study-filter-bar select {
    background: rgba(0, 0, 0, 0.4);
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: var(--text-primary);
    padding: 6px 12px;
    border-radius: 8px;
    font-family: inherit;
    font-size: 0.85rem;
    cursor: pointer;
    outline: none;
}

.queue-counter {
    font-size: 0.85rem;
    color: var(--text-secondary);
    font-weight: 600;
    background: rgba(139, 92, 246, 0.1);
    padding: 4px 10px;
    border-radius: 8px;
    border: 1px solid rgba(139, 92, 246, 0.2);
}

/* 3D Flashcard Structure */
.flashcard-wrapper {
    position: relative;
    width: 100%;
    perspective: 1200px; /* Crucial for 3D depth */
}

.flashcard {
    width: 100%;
    height: 320px;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
    cursor: pointer;
}

.flashcard.flipped {
    transform: rotateY(180deg);
}

.card-face {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden; /* Hide the reverse face during flip */
    border-radius: 28px;
    padding: 40px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.5);
    transition: border-color 0.3s ease;
}

.card-tag {
    position: absolute;
    top: 24px;
    left: 28px;
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 1.5px;
    color: var(--text-muted);
    font-weight: 600;
}

.card-tip {
    position: absolute;
    bottom: 24px;
    font-size: 0.8rem;
    color: var(--text-muted);
    letter-spacing: 0.5px;
    transition: color 0.3s ease;
}

.flashcard:hover .card-tip {
    color: var(--text-secondary);
}

/* Front Face Styles */
.card-front {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.05) 0%, rgba(255, 255, 255, 0.01) 100%);
    border: 1px solid rgba(255, 255, 255, 0.08);
}

.flashcard:hover .card-front {
    border-color: rgba(255, 255, 255, 0.18);
}

.word-text {
    font-size: 2.4rem;
    font-weight: 700;
    letter-spacing: -0.5px;
    color: #fff;
    word-break: break-word;
    max-width: 100%;
    line-height: 1.2;
}

/* Back Face Styles */
.card-back {
    background: linear-gradient(135deg, rgba(139, 92, 246, 0.08) 0%, rgba(6, 182, 212, 0.03) 100%);
    border: 1px solid rgba(139, 92, 246, 0.2);
    transform: rotateY(180deg); /* Start rotated */
}

.translation-text {
    font-size: 1.6rem;
    font-weight: 500;
    color: var(--text-primary);
    line-height: 1.5;
    word-break: break-word;
    max-width: 100%;
}

/* Floating Audio Trigger (Positioned outside the card transforms to avoid mirror/flip bugs) */
.btn-floating-audio {
    position: absolute;
    top: 20px;
    right: 20px;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.06);
    border: 1px solid rgba(255, 255, 255, 0.12);
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 10;
    transition: all 0.2s ease;
}

.btn-floating-audio svg {
    width: 20px;
    height: 20px;
    fill: var(--text-secondary);
    transition: fill 0.2s ease, transform 0.2s ease;
}

.btn-floating-audio:hover {
    background: var(--color-primary);
    border-color: var(--color-primary-hover);
    transform: scale(1.1);
}

.btn-floating-audio:hover svg {
    fill: #fff;
    transform: scale(1.05);
}

/* Keyboard legend info */
.keyboard-legend {
    font-size: 0.78rem;
    color: var(--text-muted);
    background: rgba(0, 0, 0, 0.2);
    padding: 6px 14px;
    border-radius: 10px;
}

.keyboard-legend kbd {
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 4px;
    padding: 1px 5px;
    color: var(--text-secondary);
    font-family: inherit;
    font-size: 0.75rem;
}

/* Action Wrapper */
.card-actions-wrapper {
    width: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 12px;
}

.btn-nav {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: var(--bg-card);
    border: var(--border-glass);
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: all 0.2s ease;
}

.btn-nav svg {
    width: 24px;
    height: 24px;
    fill: var(--text-secondary);
    transition: fill 0.2s ease;
}

.btn-nav:hover {
    background: rgba(255, 255, 255, 0.08);
    transform: scale(1.05);
}

.btn-nav:hover svg {
    fill: #fff;
}

/* Mastery Selection Badges */
.mastery-selectors {
    display: flex;
    gap: 10px;
    flex-grow: 1;
}

.btn-mastery {
    flex: 1;
    padding: 14px 10px;
    border-radius: 16px;
    border: 1px solid transparent;
    font-family: inherit;
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 8px;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
}

.btn-indicator {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: currentColor;
    display: inline-block;
}

/* Specific button styles */
.btn-mastery.m-l1 {
    background: var(--color-l1-bg);
    border-color: var(--color-l1-border);
    color: var(--color-l1-text);
}
.btn-mastery.m-l1:hover {
    background: rgba(251, 113, 133, 0.18);
    box-shadow: 0 0 15px var(--color-l1-glow);
    transform: translateY(-2px);
}

.btn-mastery.m-l2 {
    background: var(--color-l2-bg);
    border-color: var(--color-l2-border);
    color: var(--color-l2-text);
}
.btn-mastery.m-l2:hover {
    background: rgba(251, 191, 36, 0.18);
    box-shadow: 0 0 15px var(--color-l2-glow);
    transform: translateY(-2px);
}

.btn-mastery.m-l3 {
    background: var(--color-l3-bg);
    border-color: var(--color-l3-border);
    color: var(--color-l3-text);
}
.btn-mastery.m-l3:hover {
    background: rgba(52, 211, 153, 0.18);
    box-shadow: 0 0 15px var(--color-l3-glow);
    transform: translateY(-2px);
}

.btn-mastery.active-badge {
    outline: 2px solid #fff;
    outline-offset: -2px;
}

/* ==========================================
   2. LIST VIEW MODE STYLING
   ========================================== */

.list-controls {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 16px;
    margin-bottom: 24px;
}

.search-box {
    position: relative;
    width: 100%;
}

.search-icon {
    position: absolute;
    top: 50%;
    left: 16px;
    transform: translateY(-50%);
    width: 20px;
    height: 20px;
    fill: var(--text-muted);
}

.search-box input {
    width: 100%;
    background: var(--bg-card);
    border: var(--border-glass);
    border-radius: 16px;
    padding: 14px 16px 14px 48px;
    color: #fff;
    font-family: inherit;
    font-size: 0.95rem;
    outline: none;
    transition: all 0.3s ease;
}

.search-box input:focus {
    border-color: var(--color-primary);
    background: rgba(255, 255, 255, 0.05);
    box-shadow: 0 0 15px rgba(139, 92, 246, 0.15);
}

.filter-selectors {
    display: flex;
    gap: 10px;
}

.filter-selectors select {
    background: var(--bg-card);
    border: var(--border-glass);
    color: var(--text-primary);
    padding: 0 18px;
    border-radius: 16px;
    font-family: inherit;
    font-size: 0.9rem;
    outline: none;
    cursor: pointer;
    transition: all 0.3s ease;
}

.filter-selectors select:focus {
    border-color: var(--color-primary);
}

/* Word Cards Grid */
.words-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 16px;
}

.word-list-item {
    background: var(--bg-card);
    border: var(--border-glass);
    border-radius: 20px;
    padding: 18px;
    position: relative;
    display: flex;
    flex-direction: column;
    gap: 12px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.15);
    transition: transform 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}

.word-list-item:hover {
    transform: translateY(-2px);
    border-color: rgba(255,255,255,0.15);
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.3);
}

.item-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.item-word {
    font-size: 1.25rem;
    font-weight: 700;
    color: #fff;
    word-break: break-all;
    flex-grow: 1;
}

.item-audio-btn {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid rgba(255, 255, 255, 0.08);
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: all 0.2s ease;
    margin-left: 8px;
}

.item-audio-btn svg {
    width: 14px;
    height: 14px;
    fill: var(--text-secondary);
}

.item-audio-btn:hover {
    background: var(--color-primary);
    border-color: var(--color-primary-hover);
}

.item-audio-btn:hover svg {
    fill: #fff;
}

/* Flip Reveal Translation Box */
.item-trans-box {
    background: rgba(0, 0, 0, 0.15);
    border-radius: 12px;
    padding: 12px;
    min-height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    border: 1px dashed rgba(255, 255, 255, 0.06);
    transition: all 0.2s ease;
}

.item-trans-box:hover {
    background: rgba(255, 255, 255, 0.02);
    border-color: rgba(255, 255, 255, 0.15);
}

.item-trans-box.revealed {
    background: rgba(139, 92, 246, 0.05);
    border: 1px solid rgba(139, 92, 246, 0.12);
}

.trans-placeholder {
    font-size: 0.8rem;
    color: var(--text-muted);
    font-weight: 500;
}

.trans-content {
    font-size: 0.95rem;
    color: var(--text-primary);
    font-weight: 500;
    text-align: center;
}

/* Footer / State Badge selector */
.item-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 4px;
}

.item-badge {
    font-size: 0.75rem;
    font-weight: 600;
    padding: 3px 10px;
    border-radius: 20px;
    border: 1px solid transparent;
}

.item-badge.status-unknown {
    color: var(--color-unknown-text);
    background: var(--color-unknown-bg);
    border-color: var(--color-unknown-border);
}
.item-badge.status-l1 {
    color: var(--color-l1-text);
    background: var(--color-l1-bg);
    border-color: var(--color-l1-border);
}
.item-badge.status-l2 {
    color: var(--color-l2-text);
    background: var(--color-l2-bg);
    border-color: var(--color-l2-border);
}
.item-badge.status-l3 {
    color: var(--color-l3-text);
    background: var(--color-l3-bg);
    border-color: var(--color-l3-border);
}

/* Inline Mastery Selectors for List */
.item-state-selector {
    display: flex;
    gap: 4px;
}

.btn-state-dot {
    width: 24px;
    height: 24px;
    border-radius: 6px;
    border: 1px solid rgba(255,255,255,0.08);
    background: transparent;
    cursor: pointer;
    font-size: 0.7rem;
    font-weight: bold;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: all 0.2s ease;
}

.btn-state-dot.dot-l1 { color: var(--color-l1-text); }
.btn-state-dot.dot-l1:hover, .btn-state-dot.dot-l1.active { background: var(--color-l1-bg); border-color: var(--color-l1-border); }

.btn-state-dot.dot-l2 { color: var(--color-l2-text); }
.btn-state-dot.dot-l2:hover, .btn-state-dot.dot-l2.active { background: var(--color-l2-bg); border-color: var(--color-l2-border); }

.btn-state-dot.dot-l3 { color: var(--color-l3-text); }
.btn-state-dot.dot-l3:hover, .btn-state-dot.dot-l3.active { background: var(--color-l3-bg); border-color: var(--color-l3-border); }

/* ==========================================
   3. SETTINGS & SYNC MODE STYLING
   ========================================== */

.settings-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 20px;
    max-width: 700px;
    margin: 0 auto;
}

.settings-card {
    background: var(--bg-card);
    border: var(--border-glass);
    border-radius: 24px;
    padding: 24px;
    box-shadow: var(--shadow-glass);
}

.settings-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.settings-desc {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.5;
    margin-bottom: 16px;
}

.settings-note {
    font-size: 0.8rem;
    color: var(--text-muted);
    line-height: 1.4;
    margin-top: 8px;
}

.code-instructions {
    background: rgba(0, 0, 0, 0.3);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 12px;
    padding: 16px;
    font-family: monospace;
    font-size: 0.85rem;
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.code-title {
    color: var(--text-muted);
    font-size: 0.75rem;
    text-transform: uppercase;
    font-family: inherit;
    font-weight: bold;
}

.code-instructions code {
    color: var(--color-accent);
}

/* Backup Actions */
.backup-actions {
    display: flex;
    gap: 12px;
    margin-bottom: 16px;
}

.btn-action {
    background: var(--color-primary);
    color: #fff;
    border: none;
    padding: 12px 20px;
    border-radius: 14px;
    font-family: inherit;
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: all 0.2s ease;
}

.btn-action:hover {
    background: var(--color-primary-hover);
    transform: translateY(-1px);
}

.btn-outline {
    background: transparent;
    border: 1px solid rgba(255,255,255,0.15);
    color: var(--text-secondary);
}

.btn-outline:hover {
    background: rgba(255,255,255,0.04);
    border-color: rgba(255,255,255,0.3);
    color: #fff;
}

.icon-small {
    width: 16px;
    height: 16px;
    fill: currentColor;
}

.backup-result-box {
    display: flex;
    flex-direction: column;
    gap: 8px;
    margin-top: 14px;
    animation: fadeIn 0.3s ease;
}

.backup-result-box label {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.backup-result-box textarea {
    background: rgba(0, 0, 0, 0.4);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 12px;
    color: var(--color-accent);
    font-family: monospace;
    font-size: 0.8rem;
    padding: 12px;
    resize: none;
    height: 80px;
    outline: none;
    cursor: pointer;
}

/* Danger Zone */
.danger-zone {
    border: 1px solid rgba(239, 68, 68, 0.25);
    background: linear-gradient(180deg, rgba(255, 255, 255, 0.02) 0%, rgba(239, 68, 68, 0.02) 100%);
}

.btn-danger {
    background: rgba(239, 68, 68, 0.12);
    border: 1px solid rgba(239, 68, 68, 0.3);
    color: #ef4444;
    padding: 12px 20px;
    border-radius: 14px;
    font-family: inherit;
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: all 0.2s ease;
}

.btn-danger:hover {
    background: #ef4444;
    color: #fff;
    box-shadow: 0 0 15px rgba(239, 68, 68, 0.4);
}

/* ==========================================
   MODAL & OVERLAY SYSTEM
   ========================================== */

.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(8px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    animation: fadeIn 0.25s ease;
}

.modal-box {
    background: #1f2937;
    border: 1px solid rgba(255, 255, 255, 0.12);
    border-radius: 24px;
    padding: 28px;
    width: 90%;
    max-width: 480px;
    box-shadow: 0 20px 50px rgba(0,0,0,0.6);
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.modal-box h3 {
    font-size: 1.25rem;
}

.modal-box p {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.modal-box textarea {
    background: rgba(0, 0, 0, 0.3);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 12px;
    color: #fff;
    padding: 12px;
    font-family: monospace;
    font-size: 0.8rem;
    height: 120px;
    outline: none;
}

.modal-buttons {
    display: flex;
    justify-content: flex-end;
    gap: 10px;
}

.hidden {
    display: none !important;
}

/* ==========================================
   MEDIA QUERIES (MOBILE RESPONSIVE)
   ========================================== */

@media (max-width: 768px) {
    .app-header {
        flex-direction: column;
        gap: 16px;
        align-items: stretch;
        padding: 16px;
    }
    
    .logo-area {
        justify-content: center;
    }

    .app-nav {
        justify-content: center;
    }
    
    .nav-tab {
        padding: 8px 12px;
        font-size: 0.85rem;
    }

    .stats-dashboard {
        grid-template-columns: repeat(3, 1fr);
        gap: 10px;
    }
    
    /* On small screen, first row is total/unknown, second row is mastery levels */
    .stat-card[data-type="all"], .stat-card[data-type="unknown"] {
        grid-column: span 1;
    }
    
    .stat-num {
        font-size: 1.5rem;
    }
    
    .flashcard {
        height: 280px;
    }
    
    .word-text {
        font-size: 2rem;
    }
    
    .translation-text {
        font-size: 1.35rem;
    }

    .card-actions-wrapper {
        gap: 8px;
    }

    .btn-nav {
        width: 44px;
        height: 44px;
    }
    
    .btn-mastery {
        font-size: 0.8rem;
        padding: 12px 6px;
        border-radius: 12px;
    }

    .list-controls {
        grid-template-columns: 1fr;
        gap: 12px;
    }
    
    .filter-selectors {
        width: 100%;
    }
    
    .filter-selectors select {
        flex-grow: 1;
        padding: 12px;
        border-radius: 12px;
    }

    .words-grid {
        grid-template-columns: 1fr;
    }
    
    .keyboard-legend {
        display: none; /* Hide keyboard shortcuts on mobile devices */
    }
}

/* ==========================================
   Vocab List Switcher & Listening Badges
   ========================================== */
.vocab-switcher {
    display: flex;
    gap: 4px;
    background: rgba(0, 0, 0, 0.25);
    padding: 3px;
    border-radius: 10px;
    border: 1px solid rgba(255, 255, 255, 0.05);
    margin-left: 15px;
}

.switch-link {
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--text-secondary);
    text-decoration: none;
    padding: 4px 10px;
    border-radius: 7px;
    transition: all 0.2s ease;
}

.switch-link:hover {
    color: var(--text-primary);
}

.switch-link.active {
    color: #fff;
    background: rgba(139, 92, 246, 0.35);
    border: 1px solid rgba(139, 92, 246, 0.15);
    box-shadow: 0 0 10px rgba(139, 92, 246, 0.2);
}

.card-meta {
    position: absolute;
    top: 24px;
    right: 28px;
    display: flex;
    gap: 8px;
}

.meta-badge {
    font-size: 0.7rem;
    font-weight: 500;
    padding: 2px 8px;
    border-radius: 6px;
    border: 1px solid transparent;
}

.count-badge {
    background: rgba(6, 182, 212, 0.12);
    border-color: rgba(6, 182, 212, 0.25);
    color: var(--color-accent);
}

.years-badge {
    background: rgba(139, 92, 246, 0.12);
    border-color: rgba(139, 92, 246, 0.25);
    color: var(--color-primary-hover);
}

.item-meta {
    display: flex;
    gap: 6px;
    margin-top: -4px;
    margin-bottom: 2px;
}

@media (max-width: 600px) {
    .vocab-switcher {
        margin-left: 5px;
    }
    .switch-link {
        padding: 3px 6px;
        font-size: 0.75rem;
    }
    .card-meta {
        top: 24px;
        left: 28px;
        right: auto;
        margin-top: 24px;
    }
    .card-tag {
        top: 14px;
    }
}