/* ==========================================================================
   Flashcard & Study Session Stylesheet - Zen Minimalism / Apple / Notion Style
   ========================================================================== */

/* --------------------------------------------------------------------------
   1. 3D Flashcard Study Overlay & Ambient Layout (Full-Screen Focus)
   -------------------------------------------------------------------------- */
.study-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  width: 100vw;
  height: 100vh;
  height: 100dvh;
  background: var(--bg-primary);
  z-index: 5000;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  user-select: none;
  -webkit-user-select: none;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transform: scale(0.985);
  transition: opacity 0.18s cubic-bezier(0.16, 1, 0.3, 1), transform 0.18s cubic-bezier(0.16, 1, 0.3, 1), visibility 0.18s;
  will-change: opacity, transform;
}

.study-overlay.active {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transform: scale(1);
}

/* --------------------------------------------------------------------------
   Top Ultra-thin 2.5px Progress Line Track
   -------------------------------------------------------------------------- */
.study-progress-line-track {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 2.5px;
  background: transparent;
  z-index: 5050;
}

.study-progress-line-fill {
  height: 100%;
  background: linear-gradient(90deg, #6366f1, #8b5cf6, #3b82f6);
  transition: width 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

/* --------------------------------------------------------------------------
   Minimalist & Premium Header Bar
   -------------------------------------------------------------------------- */
.study-header-bar {
  padding: 12px clamp(8px, 2.5vw, 16px) 6px clamp(8px, 2.5vw, 16px);
  display: flex;
  justify-content: center;
  align-items: center;
  width: 100%;
  max-width: 100vw;
  box-sizing: border-box;
  background: transparent;
  position: relative;
  z-index: 20;
  flex-shrink: 0;
  overflow: hidden;
}

.study-header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  max-width: 500px;
  gap: clamp(4px, 1.2vw, 8px);
  box-sizing: border-box;
}

/* Unified Modern Action Buttons */
.btn-study-exit,
.btn-study-icon {
  width: 36px;
  height: 36px;
  border-radius: 11px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  outline: none;
  transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
  padding: 0;
  flex-shrink: 0;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.04);
}

.btn-study-exit:hover,
.btn-study-icon:hover {
  background: var(--bg-hover, rgba(0, 0, 0, 0.05));
  color: var(--text-primary);
  border-color: var(--border-hover, var(--border));
  transform: translateY(-1px);
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.08);
}

.btn-study-exit:active,
.btn-study-icon:active {
  transform: scale(0.93);
}

/* Nút Thoát Phiên Học (Esc) - Tinh tế, chuyển đỏ nhẹ nhàng khi hover */
#btn-study-close.btn-study-exit:hover {
  background: rgba(239, 68, 68, 0.1);
  color: #ef4444;
  border-color: rgba(239, 68, 68, 0.3);
}

[data-theme="dark"] #btn-study-close.btn-study-exit:hover {
  background: rgba(239, 68, 68, 0.18);
  color: #f87171;
  border-color: rgba(239, 68, 68, 0.4);
}

/* Nút Tự Động Phát / Auto-Play */
#btn-study-autoplay.btn-study-icon:hover {
  background: rgba(99, 102, 241, 0.1);
  color: #6366f1;
  border-color: rgba(99, 102, 241, 0.3);
}

[data-theme="dark"] #btn-study-autoplay.btn-study-icon:hover {
  background: rgba(99, 102, 241, 0.18);
  color: #818cf8;
  border-color: rgba(99, 102, 241, 0.4);
}

#btn-study-autoplay.btn-study-icon.active {
  color: #ffffff !important;
  background: var(--primary, #4f46e5) !important;
  border-color: var(--primary, #4f46e5) !important;
  box-shadow: 0 0 14px rgba(99, 102, 241, 0.5);
  animation: pulseAutoplay 2s infinite ease-in-out;
}

@keyframes pulseAutoplay {
  0%, 100% { transform: scale(1); box-shadow: 0 0 0 0 rgba(99, 102, 241, 0.5); }
  50% { transform: scale(1.06); box-shadow: 0 0 0 6px rgba(99, 102, 241, 0); }
}

/* Nút Chuyển Đổi Chế Độ Học (Flashcard / Quiz) */
.btn-study-mode-switch:hover {
  background: rgba(236, 72, 153, 0.1);
  color: #ec4899;
  border-color: rgba(236, 72, 153, 0.3);
}

[data-theme="dark"] .btn-study-mode-switch:hover {
  background: rgba(236, 72, 153, 0.18);
  color: #f472b6;
  border-color: rgba(236, 72, 153, 0.4);
}

/* Study Mode Toggle Group inside Drawer */
.study-mode-toggle-group {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  padding: 3px;
  border-radius: 10px;
}

[data-theme="dark"] .study-mode-toggle-group {
  background: #1e293b;
  border-color: rgba(255, 255, 255, 0.12);
}

.btn-mode-pill {
  border: none;
  background: transparent;
  color: var(--text-secondary);
  font-size: 0.78rem;
  font-weight: 700;
  padding: 5px 10px;
  border-radius: 7px;
  cursor: pointer;
  transition: all 0.2s ease;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-family: inherit;
}

.btn-mode-pill.active {
  background: var(--primary, #4f46e5);
  color: #ffffff;
  box-shadow: 0 2px 8px rgba(99, 102, 241, 0.35);
}

/* Nút Chuyển Đổi Theme */
#btn-study-theme.btn-study-icon:hover {
  background: rgba(245, 158, 11, 0.1);
  color: #d97706;
  border-color: rgba(245, 158, 11, 0.3);
}

[data-theme="dark"] #btn-study-theme.btn-study-icon:hover {
  background: rgba(245, 158, 11, 0.18);
  color: #fbbf24;
  border-color: rgba(245, 158, 11, 0.4);
}

/* Nút Tùy Chọn Hiển Thị Menu 3 Chấm */
#btn-study-menu.btn-study-icon:hover {
  background: rgba(14, 165, 233, 0.1);
  color: #0284c7;
  border-color: rgba(14, 165, 233, 0.3);
}

[data-theme="dark"] #btn-study-menu.btn-study-icon:hover {
  background: rgba(14, 165, 233, 0.18);
  color: #38bdf8;
  border-color: rgba(14, 165, 233, 0.4);
}

/* Middle Live Study Timer Capsule - Centered & Premium */
.study-header-center {
  display: flex;
  align-items: center;
  justify-content: center;
  flex: 1;
  min-width: 0;
}

.study-header-pill {
  height: 36px;
  padding: 0 14px;
  border-radius: 11px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.04);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  user-select: none;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  flex-shrink: 0;
  white-space: nowrap;
  box-sizing: border-box;
}

[data-theme="dark"] .study-header-pill {
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.25);
}

/* Thống kê thời gian học hôm nay */
.study-timer-pill {
  font-family: inherit;
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: 0.01em;
  transition: all 0.25s ease;
}

.study-timer-pill .timer-digits {
  font-family: var(--font-mono, monospace);
  font-variant-numeric: tabular-nums;
  color: var(--text-primary);
  font-weight: 700;
}

.study-timer-pill.is-idle {
  opacity: 0.7;
}

.study-timer-pill.is-idle .timer-digits {
  color: var(--text-secondary);
}

.study-header-right {
  display: flex;
  align-items: center;
  gap: clamp(3px, 1vw, 6px);
  flex-shrink: 0;
}

/* --------------------------------------------------------------------------
   2. Study Body Wrapper & Studio Canvas (One-Focus Zen Layout)
   -------------------------------------------------------------------------- */
.study-body-wrapper {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  width: 100%;
  max-width: 520px;
  margin: 0 auto;
  padding: 8px 16px 20px 16px;
  gap: 16px;
  box-sizing: border-box;
  min-height: 0;
  position: relative;
  z-index: 10;
}

/* --------------------------------------------------------------------------
   1.5. Study Pomodoro Focus Tracker Bar (Nằm giữa header và flashcard)
   -------------------------------------------------------------------------- */
.study-pomodoro-bar {
  width: 100%;
  max-width: 480px;
  background: var(--bg-card, #ffffff);
  border: 1px solid var(--border, rgba(0, 0, 0, 0.08));
  border-radius: 14px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.03);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  position: relative;
  z-index: 5;
  transition: all 0.2s ease;
  user-select: none;
  flex-shrink: 0;
  margin-bottom: -4px;
}

[data-theme="dark"] .study-pomodoro-bar {
  background: rgba(19, 27, 46, 0.85);
  border-color: rgba(255, 255, 255, 0.09);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.3);
}

.pomodoro-bar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 6px 12px;
  gap: 8px;
}

.pomodoro-timer-side {
  display: flex;
  align-items: center;
  gap: 5px;
}

.pomodoro-badge-icon {
  font-size: 0.95rem;
  line-height: 1;
}

.pomodoro-time-display {
  font-size: 0.86rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  color: var(--text-primary);
  letter-spacing: 0.02em;
}

.btn-pomodoro-control {
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 2px 4px;
  border-radius: 6px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: background 0.15s ease, transform 0.1s ease;
}

.btn-pomodoro-control:hover {
  background: rgba(0, 0, 0, 0.05);
}

[data-theme="dark"] .btn-pomodoro-control:hover {
  background: rgba(255, 255, 255, 0.08);
}

.btn-pomodoro-control:active {
  transform: scale(0.92);
}

.pomodoro-btn-icon {
  font-size: 0.7rem;
  line-height: 1;
}

.pomodoro-stats-side {
  display: flex;
  align-items: center;
  gap: 4px;
  background: rgba(99, 102, 241, 0.08);
  padding: 3px 10px;
  border-radius: 99px;
  font-size: 0.74rem;
  font-weight: 700;
  color: var(--text-secondary);
}

[data-theme="dark"] .pomodoro-stats-side {
  background: rgba(99, 102, 241, 0.18);
  color: #cbd5e1;
}

.pomodoro-stats-lbl {
  font-size: 0.72rem;
  font-weight: 600;
}

.pomodoro-count-number {
  font-size: 0.84rem;
  font-weight: 850;
  color: #4f46e5;
  font-variant-numeric: tabular-nums;
}

[data-theme="dark"] .pomodoro-count-number {
  color: #818cf8;
}

.pomodoro-stats-unit {
  font-size: 0.7rem;
  font-weight: 600;
  color: var(--text-muted);
}

.pomodoro-actions-side {
  display: flex;
  align-items: center;
  gap: 6px;
}

.pomodoro-select-wrapper {
  position: relative;
  display: inline-flex;
  align-items: center;
}

.pomodoro-select {
  appearance: none;
  -webkit-appearance: none;
  background: rgba(0, 0, 0, 0.04);
  border: 1px solid var(--border, rgba(0, 0, 0, 0.08));
  border-radius: 8px;
  padding: 3px 18px 3px 8px;
  font-size: 0.72rem;
  font-weight: 750;
  color: var(--text-primary);
  cursor: pointer;
  outline: none;
  transition: all 0.15s ease;
}

[data-theme="dark"] .pomodoro-select {
  background: rgba(255, 255, 255, 0.06);
  border-color: rgba(255, 255, 255, 0.1);
  color: #e2e8f0;
}

.pomodoro-select:hover {
  border-color: var(--primary, #6366f1);
}

.select-chevron {
  position: absolute;
  right: 5px;
  pointer-events: none;
  font-size: 0.65rem;
  color: var(--text-muted);
}

.btn-pomodoro-reset {
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 4px;
  border-radius: 6px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--text-muted);
  transition: all 0.15s ease;
}

.btn-pomodoro-reset:hover {
  color: var(--text-primary);
  background: rgba(0, 0, 0, 0.05);
  transform: rotate(-45deg);
}

[data-theme="dark"] .btn-pomodoro-reset:hover {
  background: rgba(255, 255, 255, 0.08);
  color: #ffffff;
}

.btn-pomodoro-reset:active {
  transform: scale(0.9) rotate(-90deg);
}

.pomodoro-progress-bar {
  height: 2.5px;
  width: 100%;
  background: rgba(99, 102, 241, 0.1);
  position: relative;
  overflow: hidden;
}

.pomodoro-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, #ef4444 0%, #f59e0b 50%, #10b981 100%);
  transition: width 1s linear;
}

.study-pomodoro-bar.is-paused .pomodoro-progress-fill {
  opacity: 0.5;
}

.flashcard-stage {
  width: 100%;
  flex: 0 0 auto;
  height: clamp(380px, 58vh, 480px);
  min-height: 350px;
  perspective: 1200px;
  display: flex;
  align-items: center;
  justify-content: center;
  box-sizing: border-box;
  contain: layout style;
}

.flashcard-3d-wrapper {
  width: 100%;
  height: 100%;
  position: relative;
  border-radius: 24px;
  transform-style: preserve-3d;
  -webkit-transform-style: preserve-3d;
  transition: transform 0.28s cubic-bezier(0.2, 0.8, 0.2, 1);
  cursor: pointer;
  will-change: transform;
  outline: none;
  box-shadow: 0 4px 20px -2px rgba(15, 23, 42, 0.08), 0 2px 6px -1px rgba(15, 23, 42, 0.04);
}

[data-theme="dark"] .flashcard-3d-wrapper {
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.45);
}

.flashcard-3d-wrapper.flipped {
  transform: rotateY(180deg);
}

.flashcard-3d-wrapper.no-transition {
  transition: none !important;
  -webkit-transition: none !important;
}

@keyframes cardEnterSubtle {
  0% { opacity: 0.9; transform: translateY(4px); }
  100% { opacity: 1; transform: translateY(0); }
}

.flashcard-stage.card-enter-anim {
  animation: cardEnterSubtle 0.16s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

/* Mặt trước & Mặt sau Flashcard */
.flashcard-face {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  border-radius: 24px;
  overflow: hidden;
  padding: clamp(20px, 3.8vh, 32px) clamp(20px, 5vw, 32px);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  background: var(--bg-card);
  border: 1.5px solid var(--border);
  box-sizing: border-box;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  box-shadow: 0 10px 30px -6px rgba(99, 102, 241, 0.08), 0 4px 12px rgba(0, 0, 0, 0.03);
}

[data-theme="light"] .flashcard-face {
  background: linear-gradient(180deg, #ffffff 0%, #f8fafc 100%);
  border: 1.5px solid #cbd5e1;
}

[data-theme="dark"] .flashcard-face {
  background: linear-gradient(180deg, #182236 0%, #0f172a 100%);
  border: 1.5px solid rgba(99, 102, 241, 0.3);
  box-shadow: 0 14px 40px rgba(0, 0, 0, 0.5), 0 0 20px rgba(99, 102, 241, 0.12);
}

.flashcard-face.face-front {
  transform: rotateY(0deg);
  align-items: center;
}

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

/* --------------------------------------------------------------------------
   Top Bar Status Badges
   -------------------------------------------------------------------------- */
.card-top-bar {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-shrink: 0;
  z-index: 10;
  margin-bottom: 4px;
}

.card-status-badge {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-size: 0.88rem;
  font-weight: 750;
  color: var(--text-muted);
}

.card-status-badge .status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--text-muted);
}

.card-status-badge.state-new { color: #6366f1; }
.card-status-badge.state-new .status-dot { background: #6366f1; box-shadow: 0 0 8px rgba(99, 102, 241, 0.6); }

.card-status-badge.state-learning { color: #d97706; }
.card-status-badge.state-learning .status-dot { background: #f59e0b; box-shadow: 0 0 8px rgba(245, 158, 11, 0.6); }

.card-status-badge.state-review { color: #059669; }
.card-status-badge.state-review .status-dot { background: #10b981; box-shadow: 0 0 8px rgba(16, 185, 129, 0.6); }

.card-status-badge.state-relearning { color: #dc2626; }
.card-status-badge.state-relearning .status-dot { background: #ef4444; box-shadow: 0 0 8px rgba(239, 68, 68, 0.6); }

[data-theme="dark"] .card-status-badge.state-new { color: #a5b4fc; }
[data-theme="dark"] .card-status-badge.state-learning { color: #fbbf24; }
[data-theme="dark"] .card-status-badge.state-review { color: #34d399; }
[data-theme="dark"] .card-status-badge.state-relearning { color: #f87171; }

.card-front-top-right {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.card-badges-row {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.card-pos-pill {
  font-size: 0.86rem;
  font-weight: 750;
  text-transform: lowercase;
  letter-spacing: 0.02em;
  padding: 4px 12px;
  border-radius: 99px;
  background: #f1f5f9;
  color: #475569;
  border: 1px solid #e2e8f0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  line-height: 1.2;
}

.card-leech-badge {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-size: 0.82rem;
  font-weight: 750;
  padding: 4px 10px;
  border-radius: 99px;
  background: rgba(245, 158, 11, 0.14);
  color: #d97706;
  border: 1px solid rgba(245, 158, 11, 0.35);
  animation: pulseLeech 2s infinite ease-in-out;
}

[data-theme="dark"] .card-leech-badge {
  background: rgba(245, 158, 11, 0.2);
  color: #fbbf24;
  border-color: rgba(245, 158, 11, 0.45);
}

@keyframes pulseLeech {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.82; transform: scale(0.97); }
}

.card-reps-badge {
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--text-muted);
}

[data-theme="dark"] .card-pos-pill {
  background: rgba(255, 255, 255, 0.08);
  color: #94a3b8;
  border-color: rgba(255, 255, 255, 0.14);
}

/* --------------------------------------------------------------------------
   Card Front Face: Clean Centered Typography & Hero Speaker Button
   -------------------------------------------------------------------------- */
.card-word-center {
  text-align: center;
  margin: auto 0;
  flex-shrink: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 14px;
  width: 100%;
}

/* Nút Loa Ở Trên Đầu Từ Tiếng Anh - Sinh động, Gradient & Glow */
.card-speaker-hero {
  width: 52px;
  height: 52px;
  border-radius: 50%;
  background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #d946ef 100%);
  border: none;
  color: #ffffff;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  outline: none;
  transition: all 0.22s cubic-bezier(0.16, 1, 0.3, 1);
  padding: 0;
  box-shadow: 0 6px 18px rgba(99, 102, 241, 0.35), 0 2px 6px rgba(139, 92, 246, 0.25);
  margin-bottom: 4px;
}

[data-theme="dark"] .card-speaker-hero {
  background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #d946ef 100%);
  color: #ffffff;
  box-shadow: 0 6px 20px rgba(99, 102, 241, 0.5), 0 0 15px rgba(217, 70, 239, 0.3);
}

.card-speaker-hero:hover {
  transform: scale(1.1) translateY(-2px);
  box-shadow: 0 8px 24px rgba(99, 102, 241, 0.5), 0 4px 10px rgba(217, 70, 239, 0.35);
}

[data-theme="dark"] .card-speaker-hero:hover {
  transform: scale(1.1) translateY(-2px);
  box-shadow: 0 8px 28px rgba(99, 102, 241, 0.65), 0 0 22px rgba(217, 70, 239, 0.45);
}

.card-speaker-hero:active {
  transform: scale(0.95);
}

.card-speaker-hero.playing {
  background: linear-gradient(135deg, #4f46e5 0%, #7c3aed 100%);
  color: #ffffff;
  animation: speakerPulse 1s infinite alternate;
}

[data-theme="dark"] .card-speaker-hero.playing {
  background: linear-gradient(135deg, #4f46e5 0%, #7c3aed 100%);
  color: #ffffff;
}

@keyframes speakerPulse {
  0% { transform: scale(1); box-shadow: 0 0 0 0 rgba(99, 102, 241, 0.5); }
  100% { transform: scale(1.08); box-shadow: 0 0 0 10px rgba(99, 102, 241, 0); }
}

.card-word-title {
  font-size: clamp(2.5rem, 7vw, 3.5rem);
  font-weight: 800;
  letter-spacing: -0.025em;
  color: #0f172a;
  margin: 0;
  line-height: 1.15;
  text-wrap: balance;
}

[data-theme="dark"] .card-word-title {
  color: #ffffff;
  text-shadow: 0 2px 12px rgba(0, 0, 0, 0.4);
}

.card-word-title.word-len-md { font-size: clamp(2.1rem, 5.8vw, 2.8rem); }
.card-word-title.word-len-lg { font-size: clamp(1.7rem, 4.6vw, 2.3rem); }
.card-word-title.word-len-xl { font-size: clamp(1.45rem, 3.8vw, 1.9rem); }

.card-meta-row {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}

.card-word-phonetic {
  font-size: clamp(1.15rem, 3.4vw, 1.35rem);
  color: #4338ca;
  font-weight: 600;
  font-family: var(--font-mono);
  background: rgba(99, 102, 241, 0.1);
  border: 1.5px solid rgba(99, 102, 241, 0.25);
  padding: 6px 20px;
  border-radius: 99px;
  letter-spacing: 0.03em;
  line-height: 1.3;
}

[data-theme="dark"] .card-word-phonetic {
  color: #c7d2fe;
  background: rgba(99, 102, 241, 0.2);
  border-color: rgba(99, 102, 241, 0.38);
}

.card-pos-inline {
  font-size: 0.92rem;
  color: #64748b;
  font-style: italic;
  font-weight: 600;
}

[data-theme="dark"] .card-pos-inline {
  color: #94a3b8;
}

.card-bottom-bar {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
}

.card-hint-text {
  font-size: 0.88rem;
  color: var(--text-muted);
  font-weight: 650;
}

/* --------------------------------------------------------------------------
   Card Back Face: Clean Meaning & Italic Example
   -------------------------------------------------------------------------- */
.card-back-context-word {
  display: inline-flex;
  align-items: center;
  gap: 10px;
}

.back-word-label {
  font-weight: 800;
  font-size: clamp(1.18rem, 3.4vw, 1.36rem);
  color: #4338ca;
  letter-spacing: -0.015em;
  line-height: 1.2;
}

[data-theme="dark"] .back-word-label {
  color: #a5b4fc;
}

.card-back-badges {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.card-pos-tag {
  font-size: 0.8rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  padding: 4px 10px;
  border-radius: 99px;
  background: rgba(16, 185, 129, 0.12);
  color: #059669;
  border: 1.5px solid rgba(16, 185, 129, 0.3);
  line-height: 1.2;
}

[data-theme="dark"] .card-pos-tag {
  background: rgba(16, 185, 129, 0.2);
  color: #34d399;
  border-color: rgba(16, 185, 129, 0.4);
}

.card-cefr-tag {
  font-size: 0.8rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  padding: 4px 10px;
  border-radius: 99px;
  background: rgba(249, 115, 22, 0.12);
  color: #ea580c;
  border: 1.5px solid rgba(249, 115, 22, 0.3);
  line-height: 1.2;
}

[data-theme="dark"] .card-cefr-tag {
  background: rgba(249, 115, 22, 0.2);
  color: #fb923c;
  border-color: rgba(249, 115, 22, 0.4);
}

.btn-card-audio-mini {
  background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
  border: none;
  color: #ffffff;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  min-width: 34px;
  min-height: 34px;
  border-radius: 50%;
  transition: all 0.18s cubic-bezier(0.16, 1, 0.3, 1);
  padding: 0;
  box-shadow: 0 2px 8px rgba(99, 102, 241, 0.3);
}

[data-theme="dark"] .btn-card-audio-mini {
  background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
  color: #ffffff;
  box-shadow: 0 2px 10px rgba(99, 102, 241, 0.45);
}

.btn-card-audio-mini:hover {
  transform: scale(1.1);
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.5);
}

.btn-card-audio-mini:active {
  transform: scale(0.94);
}

.card-back-center {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  margin: auto 0;
  width: 100%;
  gap: 14px;
  text-align: center;
  padding: 4px 0;
}

.card-meaning-hero {
  width: 100%;
}

.card-back-meaning {
  font-size: clamp(2.1rem, 6vw, 2.85rem);
  font-weight: 750;
  color: #0d9488;
  line-height: 1.25;
  margin: 0;
  text-wrap: balance;
  letter-spacing: -0.015em;
}

[data-theme="dark"] .card-back-meaning {
  color: #2dd4bf;
  text-shadow: 0 2px 14px rgba(45, 212, 191, 0.3);
}

.card-back-meaning.meaning-len-lg {
  font-size: clamp(1.6rem, 4.6vw, 2.15rem);
}

.card-back-def-box {
  width: 100%;
  text-align: left;
  background: rgba(99, 102, 241, 0.06);
  border-left: 4px solid #6366f1;
  border-radius: 12px;
  padding: 10px 14px;
  box-sizing: border-box;
}

[data-theme="dark"] .card-back-def-box {
  background: rgba(99, 102, 241, 0.12);
  border-left-color: #818cf8;
}

.card-back-def {
  font-size: clamp(0.98rem, 2.5vw, 1.12rem);
  font-weight: 500;
  color: #334155;
  line-height: 1.5;
  margin: 0;
}

[data-theme="dark"] .card-back-def {
  color: #cbd5e1;
}

.card-back-example {
  width: 100%;
  background: rgba(241, 245, 249, 0.9);
  border-left: 4px solid #8b5cf6;
  border-radius: 14px;
  padding: 12px 16px;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 6px;
  text-align: left;
  box-sizing: border-box;
}

[data-theme="dark"] .card-back-example {
  background: rgba(30, 41, 59, 0.75);
  border-left-color: #a78bfa;
}

.example-top-header {
  display: inline-flex;
  align-items: center;
  justify-content: flex-start;
  gap: 10px;
  width: 100%;
  margin-bottom: 4px;
}

.example-label-tag {
  font-size: 0.8rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: #6366f1;
  background: rgba(99, 102, 241, 0.12);
  padding: 4px 10px;
  border-radius: 8px;
  line-height: 1.2;
}

[data-theme="dark"] .example-label-tag {
  color: #a5b4fc;
  background: rgba(99, 102, 241, 0.22);
}

.btn-example-audio {
  background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
  border: none;
  color: #ffffff;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 30px;
  min-width: 30px;
  min-height: 30px;
  border-radius: 50%;
  transition: all 0.18s cubic-bezier(0.16, 1, 0.3, 1);
  padding: 0;
  flex-shrink: 0;
  box-shadow: 0 2px 6px rgba(99, 102, 241, 0.3);
}

[data-theme="dark"] .btn-example-audio {
  background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
  color: #ffffff;
  box-shadow: 0 2px 8px rgba(99, 102, 241, 0.45);
}

.btn-example-audio:hover {
  transform: scale(1.1);
  box-shadow: 0 3px 10px rgba(99, 102, 241, 0.45);
}

.btn-example-audio:active {
  transform: scale(0.94);
}

.card-example-en {
  font-style: normal;
  font-size: clamp(1.06rem, 2.8vw, 1.22rem);
  font-weight: 500;
  color: #334155;
  line-height: 1.55;
  margin: 0;
  text-align: left;
  width: 100%;
}

[data-theme="dark"] .card-example-en {
  color: #cbd5e1;
}

.example-highlight {
  color: #4f46e5;
  font-weight: 750;
  font-style: normal;
  text-decoration: underline;
  text-decoration-color: rgba(99, 102, 241, 0.4);
  text-underline-offset: 3px;
  background: transparent;
  padding: 0 1px;
}

[data-theme="dark"] .example-highlight {
  color: #818cf8;
  text-decoration-color: rgba(129, 140, 248, 0.5);
  background: transparent;
}

.card-example-vi {
  font-size: clamp(0.96rem, 2.5vw, 1.08rem);
  font-weight: 500;
  color: #0d9488;
  line-height: 1.5;
  margin: 0;
  text-align: left;
  width: 100%;
}

[data-theme="dark"] .card-example-vi {
  color: #5eead4;
}

/* --------------------------------------------------------------------------
   4. Cụm Nút Điều Khiển & 4 Nút Chấm Điểm Nổi Bật Tinh Tế
   -------------------------------------------------------------------------- */
.study-bottom-controls {
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  margin-top: 4px;
}

/* Nút Lật Thẻ */
.front-flip-control {
  width: 100%;
  display: none;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transform: translateY(4px);
  transition: opacity 0.18s ease, transform 0.18s ease;
}

.front-flip-control.visible {
  display: flex;
  opacity: 1;
  transform: translateY(0);
}

.btn-main-flip {
  width: 100%;
  min-height: 58px;
  padding: 14px 24px;
  border-radius: 18px;
  background: linear-gradient(135deg, #4f46e5 0%, #7c3aed 50%, #6366f1 100%);
  border: none;
  color: #ffffff;
  font-size: 1.15rem;
  font-weight: 800;
  letter-spacing: 0.015em;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
  touch-action: manipulation;
  outline: none;
  box-shadow: 0 8px 22px rgba(79, 70, 229, 0.4), 0 2px 6px rgba(124, 58, 237, 0.25);
}

.btn-main-flip:hover {
  background: linear-gradient(135deg, #4338ca 0%, #6d28d9 50%, #4f46e5 100%);
  box-shadow: 0 10px 28px rgba(79, 70, 229, 0.52), 0 4px 10px rgba(124, 58, 237, 0.35);
  transform: translateY(-2px);
}

.btn-main-flip:active {
  transform: scale(0.98);
}

/* Khóa thời gian suy nghĩ 2.5s ở Mặt trước (Active Recall Phase) */
.btn-main-flip.is-locked {
  background: var(--bg-card, rgba(0, 0, 0, 0.05));
  border: 1px solid var(--border);
  color: var(--text-secondary);
  box-shadow: none;
  cursor: not-allowed;
  opacity: 0.9;
  transform: none;
}

[data-theme="dark"] .btn-main-flip.is-locked {
  background: rgba(255, 255, 255, 0.06);
  border-color: rgba(255, 255, 255, 0.12);
  color: var(--text-secondary);
}

.btn-main-flip.is-locked:hover {
  background: var(--bg-card, rgba(0, 0, 0, 0.05));
  box-shadow: none;
  transform: none;
}

.btn-main-flip .flip-countdown-badge {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-family: var(--font-mono);
  font-size: 0.98rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: 0.01em;
}

.btn-main-flip .flip-countdown-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--primary, #4f46e5);
  box-shadow: 0 0 8px rgba(99, 102, 241, 0.6);
  animation: timerDotPulse 1.2s infinite ease-in-out;
}

.btn-main-flip.shake-cue {
  animation: shakeCueAnim 0.35s ease-in-out;
}

@keyframes shakeCueAnim {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-4px); }
  50% { transform: translateX(4px); }
  75% { transform: translateX(-2px); }
}

/* Cụm 4 Nút Đánh Giá Anki/FSRS */
.fsrs-buttons-grid {
  display: none;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
  width: 100%;
  opacity: 0;
  transform: translateY(4px);
  transition: opacity 0.18s ease, transform 0.18s ease;
}

.fsrs-buttons-grid.visible {
  display: grid;
  opacity: 1;
  transform: translateY(0);
}

.btn-fsrs-rating {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2px;
  min-height: 58px;
  padding: 8px 4px;
  border-radius: 16px;
  cursor: pointer;
  transition: all 0.18s cubic-bezier(0.16, 1, 0.3, 1);
  touch-action: manipulation;
  outline: none;
  user-select: none;
  -webkit-user-select: none;
  border: none;
  color: #ffffff;
}

.btn-fsrs-rating:hover {
  transform: translateY(-2px);
}

.btn-fsrs-rating:active {
  transform: scale(0.95);
}

.btn-fsrs-rating .fsrs-rating-title {
  font-size: 1.05rem;
  font-weight: 850;
  line-height: 1.1;
  color: #ffffff;
  letter-spacing: 0.01em;
}

.btn-fsrs-rating .fsrs-badge-interval {
  font-size: 0.82rem;
  font-family: var(--font-mono, monospace);
  font-weight: 750;
  color: rgba(255, 255, 255, 0.95);
  line-height: 1.1;
}

/* 1. Nút Lại (Again) - Đỏ chuẩn đậm đơn sắc */
.btn-fsrs-rating.again {
  background: #ef4444;
  box-shadow: 0 4px 14px rgba(239, 68, 68, 0.38);
}
.btn-fsrs-rating.again:hover {
  background: #dc2626;
  box-shadow: 0 6px 18px rgba(239, 68, 68, 0.48);
}
.btn-fsrs-rating.again:active {
  background: #b91c1c;
}

/* 2. Nút Khó (Hard) - Cam / Hổ phách chuẩn đậm đơn sắc */
.btn-fsrs-rating.hard {
  background: #f59e0b;
  box-shadow: 0 4px 14px rgba(245, 158, 11, 0.38);
}
.btn-fsrs-rating.hard:hover {
  background: #d97706;
  box-shadow: 0 6px 18px rgba(245, 158, 11, 0.48);
}
.btn-fsrs-rating.hard:active {
  background: #b45309;
}

/* 3. Nút Tốt (Good) - Xanh lá ngọc lục bảo chuẩn đậm đơn sắc */
.btn-fsrs-rating.good {
  background: #10b981;
  box-shadow: 0 4px 14px rgba(16, 185, 129, 0.38);
}
.btn-fsrs-rating.good:hover {
  background: #059669;
  box-shadow: 0 6px 18px rgba(16, 185, 129, 0.48);
}
.btn-fsrs-rating.good:active {
  background: #047857;
}

/* 4. Nút Dễ (Easy) - Xanh dương chuẩn đậm đơn sắc */
.btn-fsrs-rating.easy {
  background: #3b82f6;
  box-shadow: 0 4px 14px rgba(59, 130, 246, 0.38);
}
.btn-fsrs-rating.easy:hover {
  background: #2563eb;
  box-shadow: 0 6px 18px rgba(59, 130, 246, 0.48);
}
.btn-fsrs-rating.easy:active {
  background: #1d4ed8;
}


/* --------------------------------------------------------------------------
   6. Study Preferences Drawer (Menu 3 Chấm)
   -------------------------------------------------------------------------- */
.study-prefs-drawer {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 6000;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: opacity 0.2s ease, visibility 0.2s ease;
}

.study-prefs-drawer.active {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
}

.study-prefs-backdrop {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.65);
  backdrop-filter: blur(8px);
}

.study-prefs-content {
  position: relative;
  z-index: 10;
  width: 90%;
  max-width: 440px;
  max-height: 85vh;
  overflow-y: auto;
  scrollbar-width: thin;
  background: var(--bg-card, #131b2e);
  border: 1px solid var(--border, rgba(255, 255, 255, 0.12));
  border-radius: 22px;
  padding: 22px;
  box-shadow: 0 24px 60px rgba(0, 0, 0, 0.5);
  transform: scale(0.94);
  transition: transform 0.25s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.study-prefs-drawer.active .study-prefs-content {
  transform: scale(1);
}

[data-theme="light"] .study-prefs-content {
  background: #ffffff;
  border: 1px solid #e2e8f0;
  box-shadow: 0 20px 50px rgba(15, 23, 42, 0.16);
}

.prefs-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 8px;
}

.prefs-title-wrap {
  display: flex;
  align-items: center;
  gap: 8px;
}

.prefs-title {
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--text-primary);
  margin: 0;
}

.btn-prefs-close {
  background: transparent;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 4px;
  border-radius: 8px;
  transition: all 0.2s ease;
}

.btn-prefs-close:hover {
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-primary);
}

.prefs-desc {
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.45;
  margin-bottom: 16px;
}

.prefs-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 18px;
}

.pref-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 10px 14px;
  border-radius: 12px;
  background: var(--bg-tertiary, #1e293b);
  border: 1px solid var(--border, rgba(255, 255, 255, 0.06));
  cursor: pointer;
  transition: all 0.15s ease;
  min-height: 52px;
  box-sizing: border-box;
}

[data-theme="light"] .pref-item {
  background: #f8fafc;
  border-color: #e2e8f0;
}

.pref-item:hover {
  background: rgba(99, 102, 241, 0.08);
  border-color: rgba(99, 102, 241, 0.25);
}

.pref-info {
  display: flex;
  flex-direction: column;
  gap: 2px;
  flex: 1;
  min-width: 0;
}

.pref-label {
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--text-primary);
  display: inline-flex;
  align-items: center;
  gap: 4px;
  line-height: 1.25;
}

.autoplay-setting-label {
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--text-primary);
  display: inline-flex;
  align-items: center;
  gap: 2px;
}

.flag-icon-vn {
  width: 18px;
  height: 12px;
  border-radius: 2.5px;
  vertical-align: -1.5px;
  display: inline-block;
  margin-right: 5px;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
  flex-shrink: 0;
}

.pref-sub {
  font-size: 0.74rem;
  color: var(--text-muted);
  line-height: 1.3;
}

/* Custom Checkbox Toggle Switch */
.toggle-checkbox {
  appearance: none;
  -webkit-appearance: none;
  width: 42px;
  height: 24px;
  border-radius: 99px;
  background: rgba(148, 163, 184, 0.3);
  position: relative;
  cursor: pointer;
  outline: none;
  transition: background 0.25s ease;
  flex-shrink: 0;
  margin: 0;
}

.toggle-checkbox::before {
  content: '';
  position: absolute;
  top: 2px;
  left: 2px;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: #ffffff;
  transition: transform 0.25s cubic-bezier(0.34, 1.56, 0.64, 1);
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.25);
}

.toggle-checkbox:checked {
  background: var(--primary, #6366f1);
}

.toggle-checkbox:checked::before {
  transform: translateX(18px);
}

/* Custom Select Dropdown in Prefs Drawer */
.pref-select-dropdown {
  background: var(--bg-card, #131b2e);
  color: var(--text-primary);
  border: 1px solid var(--border, rgba(255, 255, 255, 0.15));
  border-radius: 10px;
  padding: 6px 10px;
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  outline: none;
  transition: all 0.2s ease;
  font-family: inherit;
  min-width: 140px;
  max-width: 175px;
  flex-shrink: 0;
}

[data-theme="light"] .pref-select-dropdown {
  background: #ffffff;
  border-color: #cbd5e1;
}

.pref-select-dropdown:hover,
.pref-select-dropdown:focus {
  border-color: var(--primary, #6366f1);
  box-shadow: 0 0 0 2px rgba(99, 102, 241, 0.2);
}

/* Thao Tác Thẻ Hiện Tại trong Drawer */
.prefs-card-actions-section {
  margin: 14px 0 16px 0;
  padding-top: 14px;
  border-top: 1px solid var(--border, rgba(255, 255, 255, 0.08));
}

.prefs-section-subtitle {
  font-size: 0.78rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin: 0 0 10px 0;
}

.prefs-actions-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

.btn-study-card-action {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: 12px;
  background: var(--bg-tertiary, #1e293b);
  border: 1px solid var(--border, rgba(255, 255, 255, 0.08));
  color: var(--text-primary);
  cursor: pointer;
  text-align: left;
  transition: all 0.2s ease;
}

[data-theme="light"] .btn-study-card-action {
  background: #f8fafc;
  border-color: #e2e8f0;
}

.btn-study-card-action:hover {
  background: rgba(99, 102, 241, 0.1);
  border-color: var(--primary, #6366f1);
  transform: translateY(-1px);
}

.btn-study-card-action .action-icon {
  font-size: 1.25rem;
  flex-shrink: 0;
}

.btn-study-card-action .action-text {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.btn-study-card-action .action-title {
  font-size: 0.84rem;
  font-weight: 750;
  color: var(--text-primary);
  line-height: 1.2;
}

.btn-study-card-action .action-desc {
  font-size: 0.7rem;
  color: var(--text-muted);
  line-height: 1.2;
}

.prefs-footer {
  display: flex;
  justify-content: center;
}

.btn-reset-prefs {
  background: transparent;
  border: 1px dashed var(--border, rgba(255, 255, 255, 0.2));
  color: var(--text-secondary);
  font-size: 0.8rem;
  font-weight: 700;
  padding: 8px 16px;
  border-radius: 10px;
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-reset-prefs:hover {
  border-color: var(--primary, #6366f1);
  color: var(--primary, #6366f1);
  background: rgba(99, 102, 241, 0.08);
}

/* --------------------------------------------------------------------------
   6. Study Auto-Play Customization Popover Modal
   -------------------------------------------------------------------------- */
.study-autoplay-modal {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 6000;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: opacity 0.2s ease, visibility 0.2s ease;
}

.study-autoplay-modal.active {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
}

.study-autoplay-backdrop {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.65);
  backdrop-filter: blur(8px);
}

.study-autoplay-content {
  position: relative;
  z-index: 10;
  width: 90%;
  max-width: 440px;
  max-height: 85vh;
  overflow-y: auto;
  scrollbar-width: thin;
  background: var(--bg-card, #131b2e);
  border: 1px solid var(--border, rgba(255, 255, 255, 0.12));
  border-radius: 22px;
  padding: 22px;
  box-shadow: 0 24px 60px rgba(0, 0, 0, 0.5);
  transform: scale(0.94);
  transition: transform 0.25s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.study-autoplay-modal.active .study-autoplay-content {
  transform: scale(1);
}

[data-theme="light"] .study-autoplay-content {
  background: #ffffff;
  border: 1px solid #e2e8f0;
  box-shadow: 0 20px 50px rgba(15, 23, 42, 0.16);
}

.autoplay-modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 8px;
}

.autoplay-title-wrap {
  display: flex;
  align-items: center;
  gap: 8px;
}

.autoplay-modal-icon {
  font-size: 1.25rem;
}

.autoplay-modal-title {
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--text-primary);
  margin: 0;
}

.btn-autoplay-modal-close {
  background: transparent;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 4px;
  border-radius: 8px;
  transition: all 0.2s ease;
}

.btn-autoplay-modal-close:hover {
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-primary);
}

[data-theme="light"] .btn-autoplay-modal-close:hover {
  background: rgba(0, 0, 0, 0.06);
}

.autoplay-modal-desc {
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.45;
  margin-bottom: 16px;
}

.autoplay-settings-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 18px;
}

.autoplay-setting-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 10px 14px;
  border-radius: 12px;
  background: var(--bg-tertiary, #1e293b);
  border: 1px solid var(--border, rgba(255, 255, 255, 0.06));
  transition: background 0.15s ease;
}

.autoplay-setting-item.clickable {
  cursor: pointer;
}

[data-theme="light"] .autoplay-setting-item {
  background: #f8fafc;
  border-color: #e2e8f0;
}

.autoplay-setting-item:hover {
  background: rgba(99, 102, 241, 0.08);
}

.autoplay-setting-info {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.autoplay-setting-label {
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--text-primary);
}

.autoplay-setting-sub {
  font-size: 0.74rem;
  color: var(--text-muted);
}

/* Stepper Controls */
.stepper-wrap {
  display: inline-flex;
  align-items: center;
  background: var(--bg-primary, rgba(0, 0, 0, 0.15));
  border: 1px solid var(--border, rgba(255, 255, 255, 0.1));
  border-radius: 10px;
  padding: 2px;
  gap: 2px;
  flex-shrink: 0;
}

[data-theme="light"] .stepper-wrap {
  background: #ffffff;
  border-color: #cbd5e1;
}

.btn-stepper {
  width: 28px;
  height: 28px;
  border-radius: 7px;
  border: none;
  background: var(--bg-secondary, rgba(255, 255, 255, 0.08));
  color: var(--text-primary);
  font-size: 1.05rem;
  font-weight: 800;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.15s ease;
}

[data-theme="light"] .btn-stepper {
  background: #f1f5f9;
}

.btn-stepper:hover {
  background: var(--primary, #6366f1);
  color: #ffffff;
}

.btn-stepper:active {
  transform: scale(0.9);
}

.stepper-value {
  min-width: 44px;
  text-align: center;
  font-family: var(--font-mono);
  font-weight: 800;
  font-size: 0.88rem;
  color: var(--text-primary);
}

.autoplay-modal-footer {
  display: flex;
  margin-top: 4px;
}

.btn-autoplay-main-action {
  width: 100%;
  min-height: 46px;
  border-radius: 14px;
  border: none;
  font-size: 0.98rem;
  font-weight: 800;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
  background: linear-gradient(135deg, #6366f1, #4f46e5);
  color: #ffffff;
  box-shadow: 0 4px 14px rgba(99, 102, 241, 0.35);
}

.btn-autoplay-main-action:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 18px rgba(99, 102, 241, 0.45);
}

.btn-autoplay-main-action:active {
  transform: scale(0.97);
}

.btn-autoplay-main-action.is-pause {
  background: linear-gradient(135deg, #f59e0b, #d97706);
  box-shadow: 0 4px 14px rgba(245, 158, 11, 0.35);
}

.btn-autoplay-main-action.is-pause:hover {
  box-shadow: 0 6px 18px rgba(245, 158, 11, 0.45);
}

/* --------------------------------------------------------------------------
   6. Study Session Summary Modal
   -------------------------------------------------------------------------- */
.study-summary-dialog {
  text-align: center;
  padding: 34px 28px 24px 28px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  width: 100%;
  max-width: 500px !important;
  border-radius: 24px;
  background: var(--bg-card, #131b2e);
  border: 1px solid var(--border, rgba(255, 255, 255, 0.1));
  box-shadow: 0 24px 60px rgba(0, 0, 0, 0.5);
  animation: modalPopIn 0.25s cubic-bezier(0.34, 1.56, 0.64, 1);
}

[data-theme="light"] .study-summary-dialog {
  background: #ffffff;
  border: 1px solid #e2e8f0;
  box-shadow: 0 24px 60px rgba(15, 23, 42, 0.16);
}

.summary-hero-badge {
  width: 76px;
  height: 76px;
  border-radius: 50%;
  background: linear-gradient(135deg, #fef08a, #f59e0b);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 12px 30px rgba(245, 158, 11, 0.35);
}

.summary-trophy-icon { font-size: 2.4rem; }
.summary-title { font-size: 1.4rem; font-weight: 800; color: var(--text-primary); margin-top: 2px; }
.summary-subtitle { font-size: 0.9rem; color: var(--text-secondary); line-height: 1.4; margin-top: -6px; }

.summary-stats-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  width: 100%;
}

.summary-stat-box {
  background: var(--bg-tertiary, #1e293b);
  border: 1px solid var(--border, rgba(255, 255, 255, 0.08));
  border-radius: 14px;
  padding: 12px 16px;
  display: flex;
  flex-direction: column;
  align-items: center;
}

[data-theme="light"] .summary-stat-box {
  background: #f8fafc;
  border: 1px solid #e2e8f0;
}

.summary-stat-num {
  font-size: 1.75rem;
  font-weight: 800;
  font-family: var(--font-mono, monospace);
  color: var(--text-primary);
}

.summary-stat-box.retention .summary-stat-num { color: #10b981; }

.summary-stat-lbl {
  font-size: 0.74rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  margin-top: 2px;
}

.summary-progression-section {
  display: flex;
  flex-direction: column;
  gap: 8px;
  width: 100%;
  text-align: left;
}

.summary-sec-header {
  font-size: 0.76rem;
  font-weight: 750;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.summary-progression-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px;
  width: 100%;
}

.progression-pill-card {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: 12px;
  background: var(--bg-tertiary, #1e293b);
  border: 1px solid var(--border, rgba(255, 255, 255, 0.08));
  box-sizing: border-box;
}

[data-theme="light"] .progression-pill-card {
  background: #f8fafc;
  border-color: #e2e8f0;
}

.prog-icon {
  font-size: 1.25rem;
  line-height: 1;
  flex-shrink: 0;
}

.prog-info {
  display: flex;
  flex-direction: column;
  gap: 1px;
  min-width: 0;
}

.prog-label {
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--text-muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.prog-val {
  font-size: 0.95rem;
  font-weight: 800;
  color: var(--text-primary);
  font-family: var(--font-mono, monospace);
  letter-spacing: -0.01em;
}

.prog-new .prog-val { color: #10b981; }
.prog-strengthened .prog-val { color: #6366f1; }
.prog-recovered .prog-val { color: #06b6d4; }
.prog-relearn .prog-val { color: #f59e0b; }

.summary-insight-banner {
  width: 100%;
  display: flex;
  align-items: flex-start;
  gap: 8px;
  padding: 10px 12px;
  border-radius: 12px;
  background: rgba(99, 102, 241, 0.08);
  border: 1px solid rgba(99, 102, 241, 0.2);
  text-align: left;
  box-sizing: border-box;
}

[data-theme="light"] .summary-insight-banner {
  background: rgba(99, 102, 241, 0.06);
  border-color: rgba(99, 102, 241, 0.22);
}

.insight-icon {
  font-size: 1.05rem;
  flex-shrink: 0;
  margin-top: 1px;
}

.insight-text {
  font-size: 0.8rem;
  color: var(--text-secondary);
  line-height: 1.4;
  font-weight: 500;
}

.summary-actions { width: 100%; margin-top: 4px; }

.btn-summary-home-btn {
  width: 100%;
  min-height: 48px;
  padding: 12px 20px;
  border-radius: 12px;
  font-size: 0.96rem;
  font-weight: 700;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  cursor: pointer;
}

/* --------------------------------------------------------------------------
   7. Responsive Layout Optimization (Mobile & Desktop)
   -------------------------------------------------------------------------- */
@media (max-width: 520px) {
  .study-body-wrapper {
    padding: 6px 12px 18px 12px;
    gap: 14px;
    justify-content: center;
  }
  
  .card-speaker-hero {
    width: 46px;
    height: 46px;
    margin-bottom: 0px;
  }

  .card-speaker-hero svg {
    width: 21px;
    height: 21px;
  }

  .flashcard-stage {
    height: clamp(370px, 56vh, 440px);
    min-height: 340px;
  }

  .flashcard-face {
    padding: 18px 16px;
    border-radius: 22px;
  }

  .card-pos-pill {
    font-size: 0.82rem;
    padding: 3px 9px;
  }

  .card-word-title {
    font-size: clamp(2.4rem, 8.5vw, 3.2rem);
  }

  .card-word-title.word-len-md { font-size: clamp(2rem, 7vw, 2.55rem); }
  .card-word-title.word-len-lg { font-size: clamp(1.65rem, 5.8vw, 2.1rem); }
  .card-word-title.word-len-xl { font-size: clamp(1.4rem, 4.8vw, 1.75rem); }

  .card-word-phonetic {
    font-size: clamp(1.1rem, 4vw, 1.28rem);
  }

  .card-back-meaning {
    font-size: clamp(2.15rem, 7.5vw, 2.75rem);
  }

  .card-back-meaning.meaning-len-lg {
    font-size: clamp(1.7rem, 5.8vw, 2.15rem);
  }

  .card-back-def {
    font-size: 1.04rem;
    line-height: 1.48;
  }

  .card-example-en {
    font-size: 1.05rem;
    line-height: 1.48;
  }

  .card-example-vi {
    font-size: 0.95rem;
  }

  /* Nút bấm to, rõ, êm tay và dễ chạm trên Mobile */
  .btn-main-flip {
    min-height: 60px;
    font-size: 1.18rem;
    border-radius: 16px;
    font-weight: 800;
  }

  .fsrs-buttons-grid {
    gap: 8px;
  }

  .btn-fsrs-rating {
    min-height: 62px;
    padding: 10px 2px;
    border-radius: 14px;
    gap: 3px;
  }

  .btn-fsrs-rating .fsrs-rating-title {
    font-size: 1.02rem;
    font-weight: 800;
  }

  .btn-fsrs-rating .fsrs-badge-interval {
    font-size: 0.82rem;
    font-weight: 750;
  }

  .study-summary-dialog {
    padding: 22px 16px;
    max-width: 92% !important;
    gap: 10px;
  }

  .summary-fsrs-breakdown {
    grid-template-columns: repeat(2, 1fr);
    gap: 6px;
  }
}

@media (max-width: 380px) {
  .study-header-bar {
    padding: 10px 8px 4px 8px;
  }
  .study-header-inner {
    gap: 4px;
  }
  .btn-study-exit,
  .btn-study-icon {
    width: 32px;
    height: 32px;
    border-radius: 9px;
  }
  .btn-study-exit svg,
  .btn-study-icon svg {
    width: 15px;
    height: 15px;
  }
  .btn-study-mode-switch span {
    font-size: 0.95rem !important;
  }
  .study-header-pill {
    height: 32px;
    padding: 0 6px;
    border-radius: 9px;
    gap: 3px;
  }
  .study-progress-pill {
    font-size: 0.78rem;
  }
  .study-timer-pill {
    font-size: 0.76rem;
    gap: 3px;
  }
  .study-timer-pill .timer-icon {
    font-size: 0.75rem;
  }
  .study-header-right {
    gap: 3px;
  }
}

@media (min-width: 860px) {
  .study-header-inner {
    max-width: 680px;
  }

  .study-body-wrapper {
    max-width: 620px;
    padding: 8px 20px 20px 20px;
    gap: 16px;
  }

  .flashcard-stage {
    max-width: 620px;
    height: clamp(400px, 58vh, 490px);
  }

  .flashcard-face {
    border-radius: 26px;
    padding: 22px 28px;
  }

  .card-word-title {
    font-size: clamp(2.7rem, 3.8vw, 3.6rem);
  }

  .card-back-meaning {
    font-size: clamp(2.35rem, 3.2vw, 3.2rem);
  }
}

/* ==========================================================================
   GỢI Ý NGỮ CẢNH KHUYẾT TỪ & AUDIO BLIND WAVEFORM
   ========================================================================== */
.card-cloze-hint-container {
  display: flex;
  justify-content: center;
  width: 100%;
  padding: 4px 12px;
  box-sizing: border-box;
}

.card-cloze-pill {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  max-width: 95%;
  background: rgba(99, 102, 241, 0.08);
  border: 1px dashed rgba(99, 102, 241, 0.35);
  border-radius: 14px;
  padding: 6px 14px;
  box-sizing: border-box;
  user-select: none;
  cursor: pointer;
  transition: all 0.2s ease;
}

.card-cloze-pill:hover {
  background: rgba(99, 102, 241, 0.14);
  border-color: rgba(99, 102, 241, 0.5);
  transform: translateY(-1px);
}

.card-cloze-pill .cloze-icon {
  font-size: 0.9rem;
  flex-shrink: 0;
}

.card-cloze-pill .cloze-text {
  font-size: 0.8rem;
  font-style: italic;
  line-height: 1.35;
  color: var(--text-secondary, #475569);
  text-align: center;
  word-break: break-word;
}

[data-theme="dark"] .card-cloze-pill {
  background: rgba(99, 102, 241, 0.15);
  border-color: rgba(99, 102, 241, 0.4);
}

[data-theme="dark"] .card-cloze-pill .cloze-text {
  color: #cbd5e1;
}

/* Audio Blind Mode Layout */
.card-audio-blind-wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  margin: 10px 0;
  width: 100%;
}

.audio-wave-visualizer {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  height: 36px;
}

.audio-wave-visualizer span {
  display: inline-block;
  width: 5px;
  height: 8px;
  background: linear-gradient(180deg, #6366f1 0%, #a855f7 100%);
  border-radius: 99px;
  animation: audioWaveBounce 1s ease-in-out infinite alternate;
}

.audio-wave-visualizer span:nth-child(1) { animation-delay: 0.1s; }
.audio-wave-visualizer span:nth-child(2) { animation-delay: 0.3s; }
.audio-wave-visualizer span:nth-child(3) { animation-delay: 0.5s; }
.audio-wave-visualizer span:nth-child(4) { animation-delay: 0.2s; }
.audio-wave-visualizer span:nth-child(5) { animation-delay: 0.4s; }

@keyframes audioWaveBounce {
  0% { height: 6px; opacity: 0.4; }
  100% { height: 32px; opacity: 1; }
}

.audio-blind-prompt {
  font-size: 0.76rem;
  font-weight: 750;
  letter-spacing: 0.02em;
  color: #0284c7;
  background: rgba(14, 165, 233, 0.12);
  padding: 4px 12px;
  border-radius: 99px;
}

[data-theme="dark"] .audio-blind-prompt {
  color: #38bdf8;
  background: rgba(14, 165, 233, 0.2);
}