:root {
    --color-bg: #fafafa;
    --color-surface: #ffffff;
    --color-border: #e5e7eb;
    --color-text: #1f2937;
    --color-text-muted: #6b7280;
    --color-accent: #2563eb;
    --color-accent-hover: #1d4ed8;
    --color-accent-soft: #eff6ff;
    --radius: 12px;
    --radius-sm: 6px;
    --shadow-sm: 0 1px 2px rgba(0,0,0,.05);
    --transition: .25s ease;
    --nav-height: 60px;
}

/* 強制所有可點擊元素顯示手形 cursor */
button, 
.btn, 
.btn-primary,
.btn-secondary,
.btn-outline-primary,
.btn-outline-secondary,
.btn-ghost,
.btn-sm,
select, 
.form-select,
input[type="button"],
input[type="submit"],
[onclick],
[role="button"],
.quiz-buttons button,
.toolbar-group button,
.manage-buttons button {
    cursor: pointer !important;
}

button:hover, 
.btn:hover, 
.btn-primary:hover,
.btn-secondary:hover,
.btn-outline-primary:hover,
.btn-outline-secondary:hover,
.btn-ghost:hover,
.btn-sm:hover,
select:hover, 
.form-select:hover,
input[type="button"]:hover,
input[type="submit"]:hover,
[onclick]:hover,
[role="button"]:hover,
.quiz-buttons button:hover,
.toolbar-group button:hover,
.manage-buttons button:hover {
    cursor: pointer !important;
}

/* 確保所有按鈕相關的樣式都有手形 */
* button,
* .btn,
* select,
* .form-select {
    cursor: pointer !important;
}

body.dark-theme {
    --color-bg: #0f172a;
    --color-surface: #1e293b;
    --color-border: #334155;
    --color-text: #e2e8f0;
    --color-text-muted: #94a3b8;
    --color-accent: #3b82f6;
    --color-accent-soft: rgba(59,130,246,0.15);
}

* {
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--color-bg);
    color: var(--color-text);
    margin: 0;
    line-height: 1.6;
    transition: background var(--transition), color var(--transition);
}

.app-navbar {
    background: rgba(255,255,255,0.85);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--color-border);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    height: var(--nav-height);
}

.navbar-brand {
    font-weight: 600;
    color: var(--color-accent)!important;
}

.navbar-nav .nav-link {
    color: var(--color-text)!important;
    font-weight: 500;
    padding: 0.5rem 1rem!important;
    border-radius: var(--radius-sm);
    transition: all var(--transition);
}

.navbar-nav .nav-link:hover,
.navbar-nav .nav-link.active {
    background: var(--color-accent-soft);
    color: var(--color-accent)!important;
}

.container {
    padding-top: calc(var(--nav-height) + 2rem);
    padding-bottom: 2rem;
    min-height: 100vh;
}

.btn {
    border-radius: var(--radius);
    font-weight: 500;
    padding: 0.5rem 1.25rem;
    transition: all var(--transition);
    border: none;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    cursor: pointer !important;
    pointer-events: auto !important;
    position: relative;
    z-index: 100 !important;
}

.btn-primary {
    background: var(--color-accent);
    color: white;
}

.btn-primary:hover {
    background: var(--color-accent-hover);
    color: white;
}

.btn-light {
    background: var(--color-surface);
    color: var(--color-text);
    border: 1px solid var(--color-border);
}

.btn-light:hover {
    background: var(--color-accent-soft);
    color: var(--color-accent);
    border-color: var(--color-accent);
}

.btn-ghost {
    background: transparent;
    border: 1px solid var(--color-border);
    color: var(--color-text);
}

.btn-ghost:hover {
    background: var(--color-accent-soft);
    border-color: var(--color-accent);
    color: var(--color-accent);
}

.flashcard {
    width: 300px;
    height: 400px;
    perspective: 1200px;
    margin: 1.5rem auto 2rem;
    cursor: pointer;
    border-radius: 16px;
    transition: transform 0.2s ease;
    display: block;
}

.flashcard:hover {
    transform: translateY(-2px);
}

.flashcard-inner {
    position: relative;
    width: 100%;
    height: 100%;
    text-align: center;
    transition: transform 0.42s ease;
    transform-style: preserve-3d;
}

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

.flashcard-front, 
.flashcard-back {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 2rem 1rem;
    border-radius: 16px;
    background: var(--color-surface);
    border: 3px solid var(--color-accent);
    backface-visibility: hidden;
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.15);
    transition: all 0.3s ease;
    overflow: visible;
    box-sizing: border-box;
    text-align: center;
}

.flashcard:hover .flashcard-front,
.flashcard:hover .flashcard-back {
    border-color: var(--color-accent-hover);
    box-shadow: 0 6px 20px rgba(37, 99, 235, 0.25);
}

.flashcard-front {
    z-index: 2;
}

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

.card-main-text {
    font-size: 1.6rem;
    font-weight: 600;
    line-height: 1.3;
    margin-bottom: 0.75rem;
    text-align: center;
    word-wrap: break-word;
    overflow-wrap: break-word;
    color: var(--color-text);
    position: relative;
    z-index: 1;
    width: 100%;
    display: block;
}

.pronounce {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    margin-bottom: 1rem;
    font-style: italic;
    text-align: center;
    word-wrap: break-word;
    position: relative;
    z-index: 1;
    width: 100%;
    display: block;
}

.flip-hint {
    font-size: 0.65rem;
    letter-spacing: 1px;
    text-transform: uppercase;
    color: var(--color-accent);
    background: var(--color-accent-soft);
    padding: 0.25rem 0.6rem;
    border-radius: 10px;
    margin-top: 1rem;
    font-weight: 500;
    opacity: 0.7;
    transition: opacity 0.3s ease;
    position: relative;
    z-index: 1;
    display: inline-block;
}

.flashcard:hover .flip-hint {
    opacity: 1;
}

.example-text {
    font-size: 0.85rem;
    color: var(--color-text-muted);
    line-height: 1.4;
    max-width: 90%;
    text-align: center;
    margin-top: 1rem;
}

.card-controls {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-top: 1.5rem;
    flex-wrap: wrap;
    justify-content: center;
    padding: 0 1rem;
    position: relative;
    z-index: 5;
}

.card-controls .btn {
    min-width: 80px;
    flex-shrink: 0;
    pointer-events: auto;
    z-index: 100;
    position: relative;
}

.chip {
    font-size: 0.8rem;
    padding: 0.25rem 0.75rem;
    background: var(--color-accent-soft);
    color: var(--color-accent);
    border-radius: 999px;
    white-space: nowrap;
}

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

.theme-toggle-btn {
    padding: 0.4rem 0.55rem;
    font-size: 0.9rem;
    border: 1px solid var(--color-border);
    background: var(--color-surface);
    color: var(--color-text);
    border-radius: var(--radius-sm);
    transition: all var(--transition);
}

.theme-toggle-btn:hover {
    background: var(--color-accent-soft);
    border-color: var(--color-accent);
}

.toolbar-line {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 0.75rem;
    margin-bottom: 0.75rem;
}

.toolbar-group {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.content-layout {
    display: flex;
    gap: 2rem;
    align-items: flex-start;
}

.primary-area {
    flex: 1 1 auto;
    min-width: 0;
}

.side-area {
    width: 340px;
    flex: 0 0 auto;
}

body.dark-theme .app-navbar {
    background: rgba(30,41,59,0.85);
    border-color: var(--color-border);
}

body.dark-theme .flashcard-front,
body.dark-theme .flashcard-back {
    background: var(--color-surface);
    border-color: var(--color-accent);
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.2);
}

body.dark-theme .flashcard:hover .flashcard-front,
body.dark-theme .flashcard:hover .flashcard-back {
    border-color: var(--color-accent-hover);
    box-shadow: 0 6px 20px rgba(59, 130, 246, 0.3);
}

@media (max-width: 900px) {
    .content-layout {
        flex-direction: column;
    }
    .side-area {
        width: 100%;
    }
}

@media (max-width: 768px) {
    .container {
        padding-left: 1rem;
        padding-right: 1rem;
        padding-top: calc(var(--nav-height) + 1rem);
    }
    
    .flashcard {
        width: 260px !important;
        max-width: 260px !important;
        min-width: 260px !important;
        height: 340px !important;
        min-height: 340px !important;
        margin: 1rem auto 1.5rem;
    }
    
    .flashcard-front,
    .flashcard-back {
        padding: 1.5rem 0.8rem;
    }
    
    .card-main-text {
        font-size: 1.3rem;
    }
    
    .action-toolbar {
        justify-content: stretch;
    }
    
    .action-toolbar .btn {
        flex: 1;
        min-width: 120px;
    }
}

@media (max-width: 576px) {
    .flashcard {
        width: 240px;
        height: 320px;
    }
    
    .flashcard-front,
    .flashcard-back {
        padding: 1.25rem 0.75rem;
    }
    
    .card-main-text {
        font-size: 1.1rem;
    }
}

.text-center { text-align: center; }
.text-muted { color: var(--color-text-muted); }
.mb-3 { margin-bottom: 1rem; }
.d-flex { display: flex; }
.justify-content-center { justify-content: center; }
.gap-2 { gap: 0.5rem; }

/* 確保下拉選單和按鈕可以正常點擊 */
.form-select {
    cursor: pointer !important;
    pointer-events: auto !important;
    z-index: 100 !important;
    position: relative !important;
}

.toolbar-group {
    z-index: 100 !important;
    position: relative !important;
}

.toolbar-group .btn {
    cursor: pointer !important;
    pointer-events: auto !important;
    z-index: 101 !important;
}

.quiz-buttons {
    z-index: 100 !important;
    position: relative !important;
}

.quiz-buttons .btn {
    cursor: pointer !important;
    pointer-events: auto !important;
    z-index: 101 !important;
}

/* 強制所有按鈕和選單可點擊 */
button, select, .btn, .form-select {
    cursor: pointer !important;
    pointer-events: auto !important;
}

button:hover, select:hover, .btn:hover, .form-select:hover {
    cursor: pointer !important;
}

/* 確保沒有元素阻擋點擊 */
.toolbar-line {
    position: relative !important;
    z-index: 1000 !important;
}

.toolbar-line * {
    pointer-events: auto !important;
    cursor: pointer !important;
}

/* 學習進度頁面樣式 */
.stats-summary {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.stat-item {
    background: var(--color-surface);
    padding: 1.5rem;
    border-radius: var(--radius);
    text-align: center;
    box-shadow: var(--shadow-sm);
}

.stat-label {
    font-size: 0.875rem;
    color: var(--color-text-muted);
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--color-accent);
}

.progress-layout {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
}

.mini-progress-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.mini-row {
    display: grid;
    grid-template-columns: 1fr 2fr auto;
    gap: 0.75rem;
    align-items: center;
}

.mini-label {
    font-size: 0.875rem;
    font-weight: 500;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.mini-bar-wrapper {
    height: 8px;
    background: var(--color-border);
    border-radius: 4px;
    overflow: hidden;
}

.mini-bar {
    height: 100%;
    background: var(--color-accent);
    transition: width 0.3s ease;
    border-radius: 4px;
}

.mini-bar.alt {
    background: var(--color-success);
}

.mini-value {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--color-text-muted);
    min-width: 35px;
    text-align: right;
}

.management-panel {
    grid-column: 1 / -1;
}

.manage-buttons {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.chip.overall {
    background: var(--color-accent);
    color: white;
}

.chip.alt {
    background: var(--color-success);
    color: white;
}

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

@media (max-width: 768px) {
    .progress-layout {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    
    .stats-summary {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .mini-row {
        grid-template-columns: 1fr;
        gap: 0.5rem;
        text-align: center;
    }
}