:root {
    --primary-glow: #00e5ff;
    --secondary-glow: #ff00e5;
    --background-dark: #0a0e22;
    --text-main: #e0eaff;
    --text-secondary: #a0b3d8;
    --glass-bg: rgba(20, 30, 70, 0.6);
    --glass-bg-strong: rgba(20, 30, 70, 0.8);
    --border-color: rgba(0, 229, 255, 0.3);
    --border-hover: rgba(0, 229, 255, 0.6);
    --correct-color: #00ff88;
    --incorrect-color: #ff4444;
    --warning-color: #ffdc00;
    --card-radius: 16px;
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
}

/* === Global Styles === */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    background-color: var(--background-dark);
    color: var(--text-main);
    font-family: 'Noto Sans TC', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    margin: 0;
    padding: 0;
    min-height: 100vh;
    overflow-x: hidden;
    line-height: 1.6;
}

#sci-fi-background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
}

a {
    color: var(--primary-glow);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--secondary-glow);
}

/* === Layout === */
.page-wrapper {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.main-content {
    flex: 1;
    max-width: 900px;
    width: 100%;
    margin: 0 auto;
    padding: 2rem 1.5rem;
}

/* === Shared Background Animation === */
@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

/* === Header & Navigation === */
.view-header {
    width: 100%;
    max-width: 900px;
    margin: 0 auto 2rem auto;
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 0 1.5rem;
}

.breadcrumb {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.875rem;
    color: var(--text-secondary);
    flex-wrap: wrap;
}

.breadcrumb a {
    color: var(--text-secondary);
}

.breadcrumb a:hover {
    color: var(--primary-glow);
}

.breadcrumb-separator {
    color: var(--border-color);
}

.back-btn {
    background: var(--glass-bg);
    border: 1px solid var(--border-color);
    color: var(--text-main);
    padding: 0.625rem 1.25rem;
    border-radius: 10px;
    cursor: pointer;
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all var(--transition-fast);
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    white-space: nowrap;
}

.back-btn:hover {
    background-color: rgba(0, 229, 255, 0.1);
    border-color: var(--primary-glow);
    color: var(--primary-glow);
}

.view-header h1,
.view-header h2 {
    margin: 0;
    font-size: 1.5rem;
    font-weight: 600;
    background: linear-gradient(135deg, var(--primary-glow), var(--secondary-glow));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* === Homepage Specific === */
.main-header {
    text-align: center;
    margin-bottom: 3rem;
    padding: 1rem;
    animation: fadeInUp 0.8s ease;
}

@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.main-header .logo {
    display: inline-flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
}

.main-header .logo-icon {
    font-size: 2.5rem;
    animation: float 3s ease-in-out infinite;
}

.main-header h1 {
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-bottom: 0.5rem;
}

.main-header .tagline {
    font-size: 1.125rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.section-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
    padding-left: 0.5rem;
}

.section-header::before {
    content: '';
    width: 4px;
    height: 1.5rem;
    background: linear-gradient(180deg, var(--primary-glow), var(--secondary-glow));
    border-radius: 2px;
}

.section-header h2 {
    font-size: 1.375rem;
    font-weight: 600;
    color: var(--text-main);
}

/* === Unified Card Component === */
.card {
    background: var(--glass-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--card-radius);
    padding: 1.75rem;
    text-align: center;
    transition: all var(--transition-normal);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    text-decoration: none;
    color: inherit;
    display: flex;
    flex-direction: column;
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, transparent, var(--primary-glow), transparent);
    opacity: 0;
    transition: opacity var(--transition-normal);
}

.card:hover {
    transform: translateY(-6px);
    box-shadow: 0 12px 40px rgba(0, 229, 255, 0.15);
    border-color: var(--border-hover);
}

.card:hover::before {
    opacity: 1;
}

.card-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    display: block;
    animation: float 4s ease-in-out infinite;
}

.card:nth-child(2n) .card-icon {
    animation-delay: 1s;
}

.card:nth-child(3n) .card-icon {
    animation-delay: 2s;
}

.card h3 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-main);
    margin-bottom: 0.5rem;
}

.card p {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    line-height: 1.6;
    flex: 1;
}

/* Featured card variant */
.card.featured {
    border-left: 4px solid var(--primary-glow);
    grid-column: span 1;
}

.card.featured:hover {
    border-left-color: var(--secondary-glow);
}

/* === Vocab & Library Pages === */
.content-wrapper {
    width: 100%;
    max-width: 750px;
    margin: 0 auto;
}

.vocab-card {
    background: var(--glass-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1.5rem;
    margin-bottom: 1rem;
    backdrop-filter: blur(10px);
    transition: all var(--transition-fast);
    animation: fadeInUp 0.4s ease backwards;
}

.vocab-card:hover {
    border-color: var(--border-hover);
    box-shadow: 0 4px 20px rgba(0, 229, 255, 0.1);
}

.vocab-card:last-child {
    margin-bottom: 0;
}

.vocab-card.is-playing {
    border-color: #00e5ff;
    box-shadow: 0 0 0 2px rgba(0, 229, 255, 0.6), 0 8px 32px rgba(0, 229, 255, 0.25);
    transform: translateY(-2px);
}

.vocab-row {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 1rem;
    flex-wrap: wrap;
}

.vocab-main {
    flex: 1;
    min-width: 200px;
}

.vocab-word {
    font-size: 1.75rem;
    font-weight: 600;
    color: var(--text-main);
    display: inline-flex;
    align-items: baseline;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.vocab-phon {
    font-size: 1rem;
    color: var(--primary-glow);
    font-family: 'Inter', monospace;
}

.vocab-pos {
    display: inline-block;
    background: rgba(0, 229, 255, 0.15);
    color: var(--primary-glow);
    padding: 0.25rem 0.625rem;
    border-radius: 6px;
    font-size: 0.75rem;
    font-weight: 500;
    margin-left: 0.5rem;
}

.vocab-mean {
    font-size: 1.0625rem;
    margin-top: 0.625rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

.vocab-ex {
    font-size: 0.9375rem;
    line-height: 1.7;
    margin-top: 0.75rem;
    padding-top: 0.75rem;
    border-top: 1px solid var(--border-color);
    color: var(--text-secondary);
    opacity: 0.9;
}

.vocab-ex strong {
    color: var(--text-main);
}

.playable-text {
    cursor: pointer;
    transition: color var(--transition-fast);
    position: relative;
}

.playable-text:hover {
    color: var(--primary-glow);
}

.playable-text::after {
    content: '🔊';
    margin-left: 0.375rem;
    font-size: 0.875em;
    opacity: 0.5;
    transition: opacity var(--transition-fast);
}

.playable-text:hover::after {
    opacity: 1;
}

.play-icon {
    margin-left: 0.375rem;
    font-size: 0.875em;
    filter: grayscale(50%);
    transition: filter var(--transition-fast);
}

.playable-text:hover .play-icon {
    filter: grayscale(0%);
}

.repeat-all-bar {
    text-align: center;
    margin-top: 2rem;
}

.repeat-btn-all {
    background: linear-gradient(135deg, var(--secondary-glow), #cc00b3);
    color: white;
    border: none;
    border-radius: 12px;
    padding: 1rem 2rem;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.repeat-btn-all:hover {
    transform: scale(1.02);
    box-shadow: 0 6px 20px rgba(255, 0, 229, 0.3);
}

.repeat-btn-all:active {
    transform: scale(0.98);
}

/* === Library Page Specific === */
.date-group {
    background: var(--glass-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    margin-bottom: 1rem;
    backdrop-filter: blur(10px);
    overflow: hidden;
    animation: fadeInUp 0.4s ease backwards;
}

.date-group summary {
    padding: 1.25rem 1.5rem;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    list-style: none;
    transition: background var(--transition-fast);
}

.date-group summary::-webkit-details-marker {
    display: none;
}

.date-group summary:hover {
    background: rgba(0, 229, 255, 0.05);
}

.date-group summary::after {
    content: '▼';
    font-size: 0.75rem;
    color: var(--primary-glow);
    transition: transform var(--transition-fast);
}

.date-group[open] summary::after {
    transform: rotate(180deg);
}

.date-title {
    font-size: 1.0625rem;
    font-weight: 600;
    color: var(--text-main);
}

.word-count {
    font-size: 0.8125rem;
    color: var(--text-secondary);
    background: rgba(0, 229, 255, 0.1);
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
}

.date-group-content {
    padding: 0 1.5rem 1.5rem 1.5rem;
    border-top: 1px solid var(--border-color);
}

.date-group .vocab-card {
    background: none;
    border: none;
    border-bottom: 1px solid var(--border-color);
    border-radius: 0;
    padding: 1rem 0;
    margin-bottom: 0;
    backdrop-filter: none;
    box-shadow: none;
}

.date-group .vocab-card:hover {
    border-color: var(--border-color);
    box-shadow: none;
    transform: none;
}

.date-group .vocab-card:last-child {
    border-bottom: none;
}

/* === Game Components === */
.game-controls {
    display: flex;
    justify-content: center;
    gap: 0.75rem;
    margin: 1.5rem 0;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border-radius: 10px;
    font-size: 0.9375rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    border: none;
    text-decoration: none;
    white-space: nowrap;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-glow), #00b3cc);
    color: var(--background-dark);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0, 229, 255, 0.3);
    color: var(--background-dark);
}

.btn-secondary {
    background: var(--glass-bg);
    border: 1px solid var(--border-color);
    color: var(--text-main);
}

.btn-secondary:hover {
    border-color: var(--primary-glow);
    background: rgba(0, 229, 255, 0.1);
    color: var(--primary-glow);
}

.btn-accent {
    background: linear-gradient(135deg, var(--secondary-glow), #cc00b3);
    color: white;
}

.btn-accent:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(255, 0, 229, 0.3);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none !important;
}

.feedback {
    text-align: center;
    min-height: 2.5rem;
    font-size: 1.125rem;
    font-weight: 500;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.feedback.correct {
    color: var(--correct-color);
}

.feedback.incorrect {
    color: var(--incorrect-color);
}

/* Flashcard Game */
.flashcard-container {
    perspective: 1000px;
    display: flex;
    justify-content: center;
    margin: 2rem 0;
}

.flashcard {
    width: 100%;
    max-width: 380px;
    height: 450px;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.7s cubic-bezier(0.4, 0, 0.2, 1);
    cursor: pointer;
}

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

.flashcard-face {
    padding: 2.5rem;
    box-sizing: border-box;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    background: var(--glass-bg-strong);
    border: 1px solid var(--border-color);
    border-radius: var(--card-radius);
    backdrop-filter: blur(15px);
}

.flashcard-face--back {
    transform: rotateY(180deg);
}

.flashcard-word {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.flashcard-phon {
    font-size: 1.125rem;
    color: var(--primary-glow);
    margin-bottom: 1.5rem;
}

.flashcard-mean {
    font-size: 1.125rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

.flashcard-ex {
    margin-top: 1.5rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-color);
    font-size: 0.9375rem;
    color: var(--text-secondary);
}

#progress-indicator {
    text-align: center;
    margin-bottom: 1rem;
    color: var(--text-secondary);
    font-size: 0.9375rem;
}

/* Spelling Bee Game */
.prompt-area {
    text-align: center;
    margin-bottom: 2rem;
}

.prompt-area h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

.prompt-area p {
    color: var(--primary-glow);
    font-family: 'Inter', monospace;
}

.input-area {
    display: flex;
    justify-content: center;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

#spelling-input,
#cloze-input,
#answer-input {
    font-size: 1.5rem;
    padding: 0.75rem 1.5rem;
    min-width: 280px;
    max-width: 100%;
    background: rgba(0, 0, 0, 0.3);
    border: 2px solid var(--border-color);
    color: var(--text-main);
    border-radius: 10px;
    font-family: 'Inter', monospace;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

#spelling-input:focus,
#cloze-input:focus,
#answer-input:focus {
    outline: none;
    border-color: var(--primary-glow);
    box-shadow: 0 0 0 3px rgba(0, 229, 255, 0.15);
}

#spelling-input.correct,
#cloze-input.correct,
#answer-input.correct {
    border-color: var(--correct-color);
    box-shadow: 0 0 0 3px rgba(0, 255, 136, 0.15);
}

#spelling-input.incorrect,
#cloze-input.incorrect,
#answer-input.incorrect {
    border-color: var(--incorrect-color);
    box-shadow: 0 0 0 3px rgba(255, 68, 68, 0.15);
}

/* Matching Game */
.grid-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: 12px;
    max-width: 700px;
    margin: 2rem auto;
}

.match-card {
    aspect-ratio: 1;
    min-height: 100px;
    background: var(--glass-bg);
    border: 1px solid var(--border-color);
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: all var(--transition-fast);
    border-radius: 10px;
    padding: 1rem;
    text-align: center;
}

.match-card .text {
    opacity: 0;
    transition: opacity var(--transition-fast);
    font-size: 0.9375rem;
    line-height: 1.4;
}

.match-card.flipped {
    background: linear-gradient(135deg, rgba(0, 229, 255, 0.2), rgba(0, 229, 255, 0.05));
    border-color: var(--primary-glow);
}

.match-card.flipped .text {
    opacity: 1;
    color: var(--text-main);
}

.match-card.matched {
    background: linear-gradient(135deg, rgba(0, 255, 136, 0.2), rgba(0, 255, 136, 0.05));
    border-color: var(--correct-color);
    visibility: visible;
}

.match-card.matched .text {
    opacity: 1;
    color: var(--correct-color);
}

.game-stats {
    text-align: center;
    color: var(--text-secondary);
    font-size: 1rem;
}

.game-stats span {
    color: var(--primary-glow);
    font-weight: 600;
}

/* Cloze Game */
.cloze-sentence {
    font-size: 1.25rem;
    text-align: center;
    margin: 2rem auto;
    max-width: 700px;
    line-height: 2;
}

.cloze-blank {
    display: inline-block;
    min-width: 120px;
    border-bottom: 3px solid var(--primary-glow);
    margin: 0 0.5rem;
    padding-bottom: 0.25rem;
    vertical-align: bottom;
    position: relative;
}

.cloze-blank.filled {
    border-bottom-color: var(--correct-color);
    background: rgba(0, 255, 136, 0.1);
    border-radius: 4px;
}

/* Quiz */
.quiz-view {
    display: none;
    animation: fadeInUp 0.3s ease;
}

.quiz-view.active {
    display: block;
    text-align: center;
}

.quiz-setup {
    max-width: 400px;
    margin: 0 auto;
}

.quiz-setup label {
    display: block;
    margin-bottom: 1rem;
    text-align: left;
    font-size: 0.9375rem;
    color: var(--text-secondary);
}

.quiz-setup select {
    width: 100%;
    margin-top: 0.5rem;
    padding: 0.75rem 1rem;
    background: var(--glass-bg);
    border: 1px solid var(--border-color);
    color: var(--text-main);
    border-radius: 10px;
    font-family: inherit;
    font-size: 1rem;
}

#question-container {
    font-size: 1.5rem;
    margin: 2rem 0;
    min-height: 100px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.question-word {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.question-mean {
    color: var(--text-secondary);
    font-size: 1.125rem;
}

#results-details {
    max-width: 600px;
    margin: 0 auto;
    text-align: left;
}

.result-item {
    padding: 1rem;
    background: var(--glass-bg);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    margin-bottom: 0.75rem;
    display: flex;
    align-items: center;
    gap: 1rem;
}

.result-item.correct {
    border-color: var(--correct-color);
}

.result-item.incorrect {
    border-color: var(--incorrect-color);
}

.result-icon {
    font-size: 1.5rem;
    flex-shrink: 0;
}

.result-content {
    flex: 1;
}

.result-word {
    font-weight: 600;
    font-size: 1.125rem;
}

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

.result-answer.correct {
    color: var(--correct-color);
}

.result-answer.incorrect {
    color: var(--incorrect-color);
}

/* Grammar */
.grammar-section {
    margin-bottom: 2.5rem;
}

.grammar-section h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    color: var(--text-main);
}

.grammar-section h3::before {
    content: '';
    width: 4px;
    height: 1.5rem;
    background: linear-gradient(180deg, var(--primary-glow), var(--secondary-glow));
    border-radius: 2px;
}

.topic-list {
    list-style: none;
    padding: 0;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 0.75rem;
}

.topic-list li a {
    display: block;
    padding: 1rem 1.25rem;
    background: var(--glass-bg);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    color: var(--text-main);
    transition: all var(--transition-fast);
    position: relative;
    overflow: hidden;
}

.topic-list li a::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 3px;
    background: linear-gradient(180deg, var(--primary-glow), var(--secondary-glow));
    transform: scaleY(0);
    transform-origin: bottom;
    transition: transform var(--transition-normal);
}

.topic-list li a:hover {
    background: rgba(0, 229, 255, 0.1);
    border-color: var(--border-hover);
    transform: translateX(4px);
}

.topic-list li a:hover::before {
    transform: scaleY(1);
    transform-origin: top;
}

.topic-list li a.coming-soon {
    opacity: 0.5;
    cursor: not-allowed;
}

.topic-list li a.coming-soon:hover {
    transform: none;
    background: var(--glass-bg);
}

.topic-list li a.coming-soon::after {
    content: '🚧';
    margin-left: 0.5rem;
    font-size: 0.875rem;
}

/* Footer */
.site-footer {
    text-align: center;
    padding: 2rem 1.5rem;
    border-top: 1px solid var(--border-color);
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-top: auto;
}

.site-footer a {
    color: var(--text-secondary);
}

.site-footer a:hover {
    color: var(--primary-glow);
}

/* Loading State */
.loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 200px;
    gap: 1rem;
    color: var(--text-secondary);
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border-color);
    border-top-color: var(--primary-glow);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Error State */
.error-message {
    text-align: center;
    padding: 3rem;
    background: var(--glass-bg);
    border: 1px solid var(--incorrect-color);
    border-radius: var(--card-radius);
    color: var(--incorrect-color);
}

.error-message h3 {
    margin-bottom: 0.5rem;
}

/* Responsive */
@media (max-width: 640px) {
    .main-content {
        padding: 1.5rem 1rem;
    }
    
    .view-header {
        padding: 0 1rem;
        flex-wrap: wrap;
    }
    
    .view-header h1,
    .view-header h2 {
        font-size: 1.25rem;
    }
    
    .card-grid {
        grid-template-columns: 1fr;
    }
    
    .vocab-word {
        font-size: 1.5rem;
    }
    
    .flashcard {
        height: 400px;
    }
    
    .grid-container {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .topic-list {
        grid-template-columns: 1fr;
    }
    
    .input-area {
        flex-direction: column;
        align-items: center;
    }
    
    #spelling-input,
    #cloze-input,
    #answer-input {
        width: 100%;
        min-width: auto;
    }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    .flashcard {
        transition: none;
    }
    
    .card-icon {
        animation: none;
    }
}

/* Print */
@media print {
    #sci-fi-background,
    .view-header,
    .game-controls,
    .repeat-all-bar,
    .btn,
    #global-stop-btn {
        display: none !important;
    }
    
    body {
        background: white;
        color: black;
    }
    
    .vocab-card,
    .date-group,
    .card {
        border: 1px solid #ccc;
        background: white;
        box-shadow: none;
    }
}

.repeat-icon {
    margin-left: 0.375rem;
    font-size: 0.875em;
    filter: grayscale(50%);
    transition: filter var(--transition-fast);
}
.playable-text:hover .repeat-icon {
    filter: grayscale(0%);
}

/* === 課本單字：版本切換 + 單元標題 === */
.version-switch {
    display: flex;
    gap: 0.5rem;
    justify-content: center;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}
.version-btn {
    background: var(--glass-bg);
    border: 1px solid var(--border-color);
    color: var(--text-main);
    padding: 0.5rem 1.25rem;
    border-radius: 999px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all var(--transition-fast);
    white-space: nowrap;
}
.version-btn:hover {
    border-color: var(--primary-glow);
    color: var(--primary-glow);
}
.version-btn.active {
    background: rgba(0, 229, 255, 0.15);
    border-color: var(--primary-glow);
    color: var(--primary-glow);
    font-weight: 600;
}
.unit-title {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--primary-glow);
    margin: 1rem 0 0.5rem;
    padding-left: 0.5rem;
    border-left: 3px solid var(--primary-glow);
}

/* === 課本單字：單元再收納一層 === */
.unit-group {
    background: rgba(20, 30, 70, 0.35);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    margin: 0.75rem 0;
    overflow: hidden;
}
.unit-group summary {
    padding: 0.75rem 1rem;
    cursor: pointer;
    list-style: none;
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-main);
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: background var(--transition-fast);
}
.unit-group summary::-webkit-details-marker { display: none; }
.unit-group summary:hover { background: rgba(0, 229, 255, 0.05); }
.unit-group summary::after {
    content: '▼';
    font-size: 0.7rem;
    color: var(--primary-glow);
    transition: transform var(--transition-fast);
}
.unit-group[open] summary::after { transform: rotate(180deg); }
.unit-group .unit-wordlist { padding: 0 1rem 1rem 1rem; }
.unit-word-count {
    font-size: 0.75rem;
    color: var(--text-secondary);
    background: rgba(0, 229, 255, 0.1);
    padding: 0.2rem 0.6rem;
    border-radius: 20px;
}

/* 單元播放全部按鈕 */
.unit-play-all {
    background: rgba(0, 229, 255, 0.15);
    border: 1px solid var(--primary-glow);
    color: var(--primary-glow);
    padding: 0.25rem 0.75rem;
    border-radius: 999px;
    cursor: pointer;
    font-size: 0.75rem;
    font-weight: 500;
    white-space: nowrap;
    transition: all var(--transition-fast);
}
.unit-play-all:hover {
    background: rgba(0, 229, 255, 0.25);
}
.unit-play-all:disabled {
    opacity: 0.6;
    cursor: default;
}

/* === 全域固定停止播放按鈕樣式 (置於右下角) === */
#global-stop-btn {
    position: fixed !important;
    bottom: 30px !important;
    right: 30px !important;
    z-index: 999999 !important;
    background-color: #ff6b6b !important;
    color: white !important;
    border: none !important;
    padding: 12px 20px !important;
    border-radius: 30px !important;
    font-weight: 700 !important;
    font-size: 1rem !important;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.4) !important;
    cursor: pointer !important;
    display: block !important;
    transition: transform 0.2s, background-color 0.2s !important;
}

#global-stop-btn:hover {
    background-color: #ff5252 !important;
    transform: scale(1.08) !important;
}