/* ══════════════════════════════════════════════════════════
   study.css — Kavi Quiz Engine Styles
   ══════════════════════════════════════════════════════════ */

/* ── Design Tokens (bridged to theme.css) ────────────── */
:root {
  --kq-bg: var(--kv-bg);
  --kq-surface: var(--kv-surface-alpha);
  --kq-surface-solid: var(--kv-surface);
  --kq-border: var(--kv-border);
  --kq-text: var(--kv-text);
  --kq-text-sub: var(--kv-text-sub);
  --kq-primary: var(--kv-primary-dark);
  --kq-known: #10b981;
  --kq-review: #f59e0b;
  --kq-wrong: #EF4444;
  --kq-purple: #8B5CF6;
  --kq-card-radius: 28px;
  --kq-flip-duration: 0.5s;
  --kq-exit-duration: 320ms;
}

/* ── Panel System ─────────────────────────────────────── */
.kq-panel { display: none; }
.kq-panel.active { display: flex; }

.kq-fullscreen {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  height: 100dvh;
  background: var(--kq-bg);
  z-index: 1000;
  flex-direction: column;
  overflow: hidden;
}

/* ── Loading ──────────────────────────────────────────── */
#kq-loading {
  align-items: center;
  justify-content: center;
  gap: 16px;
}
.kq-spinner {
  width: 40px; height: 40px;
  border: 3px solid var(--kq-border);
  border-top-color: var(--kq-primary);
  border-radius: 50%;
  animation: kq-spin 0.8s linear infinite;
}
@keyframes kq-spin {
  to { transform: rotate(360deg); }
}

/* ── Error ────────────────────────────────────────────── */
#kq-error {
  align-items: center;
  justify-content: center;
  gap: 12px;
  padding: 32px;
  text-align: center;
}
.kq-error-icon { font-size: 48px; color: var(--kq-text-sub); }
.kq-error-msg { color: var(--kq-text); font-size: 16px; font-weight: 600; }
.kq-retry-btn {
  margin-top: 8px;
  padding: 12px 24px;
  background: var(--kq-primary);
  color: #fff;
  border: none;
  border-radius: 12px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
}

/* ── Cover Screen ─────────────────────────────────────── */
#kq-cover {
  flex-direction: column;
}
.kq-cover-header {
  display: flex;
  align-items: center;
  padding: 16px;
}
.kq-cover-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 16px;
  padding: 0 32px;
}
.kq-cover-icon { font-size: 64px; color: var(--kq-primary); }
.kq-cover-title {
  font-size: 28px;
  font-weight: 700;
  color: var(--kq-text);
  text-align: center;
}
.kq-cover-desc {
  font-size: 16px;
  color: var(--kq-text-sub);
  text-align: center;
  line-height: 1.5;
}
.kq-cover-badge {
  display: inline-block;
  padding: 8px 16px;
  background: rgba(16,185,129,0.1);
  color: var(--kq-primary);
  border-radius: 20px;
  font-size: 15px;
  font-weight: 600;
}
.kq-cover-footer {
  padding: 16px 16px 32px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.kq-cover-learn-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 56px;
  border-radius: 16px;
  gap: 8px;
  border: 2px solid var(--kq-primary);
  background: transparent;
  color: var(--kq-primary);
  font-size: 17px;
  font-weight: 700;
  cursor: pointer;
}
.kq-cover-start-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 56px;
  border-radius: 16px;
  gap: 8px;
  background: var(--kq-primary);
  color: #fff;
  border: none;
  font-size: 17px;
  font-weight: 700;
  cursor: pointer;
}

/* ── Close Button ─────────────────────────────────────── */
.kq-close-btn {
  width: 48px; height: 48px;
  border-radius: 24px;
  background: var(--kq-surface-solid);
  border: none;
  color: var(--kq-text);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  font-size: 22px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.15);
  flex-shrink: 0;
}

/* ── Learn Mode ───────────────────────────────────────── */
#kq-learn {
  flex-direction: column;
}
.kq-learn-header {
  display: flex;
  align-items: center;
  padding: 12px 16px;
  gap: 12px;
}
.kq-learn-title {
  flex: 1;
  font-size: 18px;
  font-weight: 700;
  color: var(--kq-text);
  text-align: center;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.kq-learn-switch-btn {
  display: flex;
  align-items: center;
  padding: 8px 12px;
  border-radius: 20px;
  border: 1.5px solid var(--kq-primary);
  background: transparent;
  color: var(--kq-primary);
  font-size: 14px;
  font-weight: 600;
  gap: 4px;
  cursor: pointer;
  flex-shrink: 0;
}
.kq-learn-scroll {
  flex: 1;
  overflow-y: auto;
  padding: 8px 16px 40px;
  -webkit-overflow-scrolling: touch;
}
.kq-learn-card {
  background: var(--kq-surface);
  border: 1px solid var(--kq-border);
  border-radius: 16px;
  padding: 20px;
  margin-bottom: 12px;
}
.kq-learn-card-num {
  font-size: 13px;
  font-weight: 600;
  color: var(--kq-text-sub);
  text-align: center;
  margin-bottom: 8px;
}
.kq-learn-card-q {
  color: var(--kq-text);
  font-size: 16px;
  line-height: 1.5;
}
.kq-learn-divider {
  height: 1px;
  background: var(--kq-border);
  margin: 12px 0;
}
.kq-learn-card-a {
  color: var(--kq-primary);
  font-size: 15px;
  line-height: 1.5;
}
.kq-learn-cta {
  background: rgba(16,185,129,0.07);
  border: 1px solid rgba(16,185,129,0.2);
  border-radius: 16px;
  padding: 24px;
  margin-top: 4px;
  text-align: center;
}
.kq-learn-cta-title {
  font-size: 17px;
  font-weight: 700;
  color: var(--kq-text);
  margin-bottom: 14px;
}
.kq-learn-cta-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 48px;
  padding: 0 24px;
  background: var(--kq-primary);
  color: #fff;
  border: none;
  border-radius: 14px;
  font-size: 16px;
  font-weight: 700;
  gap: 8px;
  cursor: pointer;
}

/* ── Flashcard Mode ───────────────────────────────────── */
#kq-flashcard {
  flex-direction: column;
  position: relative;
}

.kq-fc-chrome {
  position: absolute;
  top: 0; left: 0; right: 0;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  padding: 16px;
  z-index: 30;
  pointer-events: none;
}
.kq-fc-chrome > * { pointer-events: auto; }

.kq-score-counters {
  display: flex;
  align-items: center;
  gap: 3px;
  padding-top: 12px;
}
.kq-score-review { color: var(--kq-review); font-size: 18px; font-weight: 700; }
.kq-score-divider { color: var(--kq-text-sub); font-size: 16px; }
.kq-score-known { color: var(--kq-known); font-size: 18px; font-weight: 700; }

/* Card area */
.kq-card-area {
  flex: 1 1 0%;
  position: relative;
  padding: 8px;
  overflow: hidden;
  min-height: 0;
}

/* Peek cards */
.kq-peek-card {
  position: absolute;
  width: calc(100% - 16px);
  height: calc(100% - 16px);
  background: var(--kq-surface);
  border-radius: var(--kq-card-radius);
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
}
.kq-peek-1 { transform: scale(0.96); top: 16px; opacity: 0.7; }
.kq-peek-2 { transform: scale(0.92); top: 24px; opacity: 0.4; }

/* Active card container */
.kq-card-container {
  width: 100%;
  height: 100%;
  position: absolute;
  inset: 0;
  touch-action: none;
  user-select: none;
  -webkit-user-select: none;
  will-change: transform;
  cursor: grab;
}
.kq-card-container:active { cursor: grabbing; }

/* 3D Flip card */
.kq-card {
  position: absolute;
  width: 100%;
  height: 100%;
  border-radius: var(--kq-card-radius);
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  box-shadow: 0 4px 20px rgba(0,0,0,0.15);
  display: flex;
  flex-direction: column;
  padding: 72px 28px 110px;
  cursor: pointer;
  overflow: hidden;
  transition: transform var(--kq-flip-duration) cubic-bezier(0.4, 0, 0.2, 1);
}
.kq-card-front {
  background: var(--kq-surface);
  transform: perspective(2000px) rotateY(0deg);
}
.kq-card-back {
  background: #1a3a2f;
  transform: perspective(2000px) rotateY(180deg);
}
.kq-card-container.flipped .kq-card-front {
  transform: perspective(2000px) rotateY(180deg);
}
.kq-card-container.flipped .kq-card-back {
  transform: perspective(2000px) rotateY(360deg);
}

.kq-card-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  overflow-y: auto;
  text-align: center;
}
.kq-card-q {
  font-size: 24px;
  font-weight: 600;
  color: var(--kq-text);
  line-height: 1.4;
  text-align: center;
  max-width: 600px;
}
.kq-card-a {
  font-size: 22px;
  font-weight: 600;
  color: var(--kq-known);
  line-height: 1.4;
  text-align: center;
  max-width: 600px;
}
.kq-card-q-context {
  font-size: 13px;
  font-style: italic;
  color: var(--kq-text-sub);
  text-align: center;
  margin-bottom: 16px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.kq-tap-hint {
  text-align: center;
  margin-top: 16px;
}
.kq-tap-hint-text {
  font-size: 13px;
  color: var(--kq-text-sub);
}
.kq-swipe-hint-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 4px;
  margin-top: 4px;
  font-size: 12px;
}

/* Swipe overlays */
.kq-swipe-overlay {
  position: absolute;
  inset: 0;
  border-radius: var(--kq-card-radius);
  pointer-events: none;
  z-index: 10;
  opacity: 0;
  transition: opacity 0.05s linear;
}
.kq-overlay-known { background: var(--kq-known); }
.kq-overlay-review { background: var(--kq-review); }

/* Stamps */
.kq-stamp {
  position: absolute;
  z-index: 12;
  top: 72px;
  font-size: 28px;
  font-weight: 800;
  border: 3px solid;
  border-radius: 8px;
  padding: 4px 12px;
  opacity: 0;
  pointer-events: none;
}
.kq-stamp-known {
  left: 24px;
  color: var(--kq-known);
  border-color: var(--kq-known);
  transform: rotate(12deg);
}
.kq-stamp-review {
  right: 24px;
  color: var(--kq-review);
  border-color: var(--kq-review);
  transform: rotate(-12deg);
}

/* ── Progress Bar ─────────────────────────────────────── */
.kq-progress-bar {
  display: flex;
  gap: 2px;
  margin-bottom: 8px;
  padding: 0;
}
.kq-progress-seg {
  flex: 1;
  height: 2px;
  border-radius: 1px;
  background: var(--kq-border);
  transition: background 0.3s;
}
.kq-progress-seg.known { background: var(--kq-known); }
.kq-progress-seg.review { background: var(--kq-review); }
.kq-progress-seg.current { background: rgba(16,185,129,0.25); }

/* ── Footer Buttons ───────────────────────────────────── */
.kq-fc-footer {
  display: flex;
  padding: 8px 16px 32px;
  gap: 12px;
}
.kq-fc-action-btn {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  height: 56px;
  border-radius: 16px;
  gap: 8px;
  border: none;
  cursor: pointer;
  font-size: 17px;
  font-weight: 600;
}
.kq-btn-review {
  background: #3a2a1a;
  color: var(--kq-review);
}
.kq-btn-known {
  background: #1a3a2f;
  color: var(--kq-known);
}

/* ── Coach Overlay ────────────────────────────────────── */
.kq-coach-overlay {
  position: absolute;
  inset: 0;
  z-index: 50;
  background: rgba(0,0,0,0.6);
  border-radius: var(--kq-card-radius);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 24px;
}
.kq-coach-content {
  display: flex;
  align-items: center;
  gap: 32px;
}
.kq-coach-arrow {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  animation: kq-coach-ping 1s ease-in-out infinite alternate;
}
.kq-coach-arrow-icon {
  font-size: 48px;
}
.kq-coach-arrow-label {
  font-size: 14px;
  font-weight: 600;
}
.kq-coach-title {
  color: #fff;
  font-size: 18px;
  font-weight: 700;
}
.kq-coach-btn {
  background: var(--kq-primary);
  color: #fff;
  border: none;
  padding: 12px 32px;
  border-radius: 24px;
  font-size: 16px;
  font-weight: 700;
  cursor: pointer;
}
@keyframes kq-coach-ping {
  from { transform: scale(1); }
  to   { transform: scale(1.15); }
}

/* ── Idle Nudge ───────────────────────────────────────── */
@keyframes kq-nudge {
  0%   { transform: translateX(0); }
  25%  { transform: translateX(18px); }
  50%  { transform: translateX(0); }
  75%  { transform: translateX(-18px); }
  100% { transform: translateX(0); }
}
.kq-card-container.nudging {
  animation: kq-nudge 0.8s ease-in-out;
}

/* ── Card exit/snapback animations ────────────────────── */
.kq-card-container.exit-right {
  transition: transform var(--kq-exit-duration) cubic-bezier(0.4, 0, 1, 1);
  transform: translateX(120vw) rotate(12deg) !important;
}
.kq-card-container.exit-left {
  transition: transform var(--kq-exit-duration) cubic-bezier(0.4, 0, 1, 1);
  transform: translateX(-120vw) rotate(-12deg) !important;
}
.kq-card-container.exit-down {
  transition: transform var(--kq-exit-duration) cubic-bezier(0.4, 0, 1, 1);
  transform: translateY(120vh) !important;
}
.kq-card-container.snap-back {
  transition: transform 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  transform: translateX(0) translateY(0) rotate(0deg) !important;
}

/* ── Entrance animation ───────────────────────────────── */
.kq-card-container.entrance {
  animation: kq-entrance 0.35s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}
@keyframes kq-entrance {
  from { opacity: 0.6; transform: scale(0.92); }
  to   { opacity: 1;   transform: scale(1); }
}

/* ══════════════════════════════════════════════════════════
   MCQ Mode
   ══════════════════════════════════════════════════════════ */
#kq-mcq {
  flex-direction: column;
}
.kq-quiz-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 16px;
}
.kq-quiz-header-title {
  font-size: 17px;
  font-weight: 700;
  color: var(--kq-text);
}
.kq-timer-badge {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 5px 10px;
  border-radius: 12px;
  background: var(--kq-surface);
  font-size: 13px;
  font-weight: 600;
  color: var(--kq-text-sub);
}
.kq-timer-badge.danger {
  background: rgba(239,68,68,0.12);
  color: var(--kq-wrong);
}

/* Linear progress */
.kq-linear-progress {
  height: 4px;
  margin: 0 16px;
  border-radius: 2px;
  background: var(--kq-border);
  overflow: hidden;
}
.kq-linear-progress-fill {
  height: 100%;
  border-radius: 2px;
  background: var(--kq-primary);
  transition: width 0.3s ease;
}
.kq-progress-label {
  font-size: 12px;
  text-align: center;
  color: var(--kq-text-sub);
  margin: 6px 0 4px;
}

/* Question area */
.kq-question-area {
  flex: 1;
  overflow-y: auto;
  padding: 16px 20px 40px;
  -webkit-overflow-scrolling: touch;
  transition: opacity 0.2s;
}
.kq-question-text {
  font-size: 20px;
  font-weight: 700;
  line-height: 1.4;
  color: var(--kq-text);
  margin-bottom: 24px;
}

/* MCQ Choices */
.kq-choices { display: flex; flex-direction: column; gap: 10px; }
.kq-choice {
  display: flex;
  align-items: center;
  padding: 16px;
  border-radius: 16px;
  border: 1.5px solid var(--kq-border);
  background: var(--kq-surface);
  cursor: pointer;
  transition: all 0.2s;
  color: var(--kq-text);
}
.kq-choice:hover:not(.answered) {
  border-color: rgba(255,255,255,0.15);
}
.kq-choice.answered { pointer-events: none; }
.kq-choice.correct {
  background: rgba(16,185,129,0.1);
  border-color: var(--kq-known);
  color: var(--kq-known);
}
.kq-choice.wrong {
  background: rgba(239,68,68,0.1);
  border-color: var(--kq-wrong);
  color: var(--kq-wrong);
}
.kq-choice.dimmed {
  color: var(--kq-text-sub);
}
.kq-choice-letter {
  width: 32px; height: 32px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-right: 12px;
  font-size: 14px;
  font-weight: 700;
  background: rgba(255,255,255,0.05);
  flex-shrink: 0;
}
.kq-choice.correct .kq-choice-letter { background: rgba(16,185,129,0.2); }
.kq-choice.wrong .kq-choice-letter { background: rgba(239,68,68,0.2); }
.kq-choice-text { flex: 1; font-size: 15px; line-height: 1.45; }
.kq-choice-icon { margin-left: 8px; font-size: 22px; flex-shrink: 0; }

/* ══════════════════════════════════════════════════════════
   True/False Mode
   ══════════════════════════════════════════════════════════ */
#kq-tf {
  flex-direction: column;
}
.kq-tf-area {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 20px;
  transition: opacity 0.2s;
}
.kq-tf-statement-box {
  text-align: center;
  padding: 0 16px;
  margin-bottom: 40px;
}
.kq-tf-icon { font-size: 28px; color: var(--kq-primary); margin-bottom: 16px; }
.kq-tf-statement {
  font-size: 22px;
  font-weight: 700;
  color: var(--kq-text);
  line-height: 1.45;
  text-align: center;
}
.kq-tf-row {
  display: flex;
  gap: 14px;
  padding: 0 8px;
}
.kq-tf-btn {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 24px 0;
  border-radius: 20px;
  border: 2px solid var(--kq-border);
  background: var(--kq-surface);
  cursor: pointer;
  gap: 8px;
  transition: all 0.2s;
  color: var(--kq-text);
}
.kq-tf-btn:hover:not(.answered) {
  border-color: rgba(255,255,255,0.15);
}
.kq-tf-btn.answered { pointer-events: none; }
.kq-tf-btn.correct {
  background: rgba(16,185,129,0.1);
  border-color: var(--kq-known);
  color: var(--kq-known);
}
.kq-tf-btn.wrong {
  background: rgba(239,68,68,0.1);
  border-color: var(--kq-wrong);
  color: var(--kq-wrong);
}
.kq-tf-btn.dimmed {
  color: var(--kq-text-sub);
}
.kq-tf-btn-icon { font-size: 28px; }
.kq-tf-btn-label { font-size: 18px; font-weight: 700; }

/* ══════════════════════════════════════════════════════════
   Results Panel (shared MCQ + TF)
   ══════════════════════════════════════════════════════════ */
.kq-results-panel {
  flex-direction: column;
}
.kq-results-scroll {
  flex: 1;
  overflow-y: auto;
  padding: 24px 20px 40px;
  -webkit-overflow-scrolling: touch;
}
.kq-results-content {
  display: flex;
  flex-direction: column;
  align-items: center;
}
.kq-score-circle {
  width: 140px; height: 140px;
  border-radius: 70px;
  border: 6px solid;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
}
.kq-score-pct { font-size: 36px; font-weight: 800; }
.kq-score-label { font-size: 14px; color: var(--kq-text-sub); margin-top: 2px; }
.kq-score-msg { font-size: 20px; font-weight: 700; color: var(--kq-text); margin-bottom: 24px; }

.kq-review-header {
  font-size: 16px;
  font-weight: 700;
  color: var(--kq-text);
  align-self: flex-start;
  margin: 8px 0 12px;
}
.kq-review-card {
  width: 100%;
  padding: 14px;
  border-radius: 14px;
  border: 1px solid var(--kq-border);
  background: var(--kq-surface);
  margin-bottom: 10px;
}
.kq-review-q { font-size: 15px; font-weight: 600; color: var(--kq-text); margin-bottom: 8px; line-height: 1.45; }
.kq-review-wrong { font-size: 13px; color: var(--kq-wrong); margin-bottom: 4px; }
.kq-review-correct { font-size: 13px; color: var(--kq-known); font-weight: 600; }

.kq-actions-row {
  display: flex;
  gap: 12px;
  margin-top: 24px;
  width: 100%;
}
.kq-action-btn {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 14px 0;
  border-radius: 14px;
  gap: 6px;
  border: none;
  cursor: pointer;
  font-size: 15px;
  font-weight: 600;
}
.kq-action-btn.primary { background: var(--kq-primary); color: #fff; }
.kq-action-btn.secondary {
  background: var(--kq-surface);
  color: var(--kq-text);
  border: 1px solid var(--kq-border);
}

/* ══════════════════════════════════════════════════════════
   Completion Panel (Flashcard)
   ══════════════════════════════════════════════════════════ */
#kq-completion {
  flex-direction: column;
}
.kq-completion-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: 20px;
  animation: kq-slide-up 0.5s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}
@keyframes kq-slide-up {
  from { opacity: 0; transform: translateY(80px); }
  to   { opacity: 1; transform: translateY(0); }
}
.kq-hero-pct {
  font-size: 56px;
  font-weight: 800;
  color: var(--kq-text);
  margin-bottom: 4px;
}
.kq-grade-text {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 20px;
}
.kq-completion-icon {
  width: 80px; height: 80px;
  border-radius: 40px;
  background: #1a3a2f;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
  font-size: 48px;
  color: var(--kq-known);
  animation: kq-bounce-in 0.6s cubic-bezier(0.34, 1.56, 0.64, 1);
}
@keyframes kq-bounce-in {
  from { transform: scale(0); }
  to   { transform: scale(1); }
}
.kq-completion-title {
  font-size: 24px;
  font-weight: 700;
  color: var(--kq-text);
  margin-bottom: 8px;
}
.kq-completion-subtitle {
  font-size: 16px;
  color: var(--kq-text-sub);
  margin-bottom: 24px;
}
.kq-stats-row {
  display: flex;
  gap: 12px;
  width: 100%;
  max-width: 360px;
  margin-bottom: 20px;
}
.kq-stat-box {
  flex: 1;
  text-align: center;
  padding: 16px;
  border-radius: 16px;
}
.kq-stat-box.known { background: #1a3a2f; }
.kq-stat-box.review-box { background: #3a2a1a; }
.kq-stat-num { font-size: 32px; font-weight: 700; }
.kq-stat-label { font-size: 14px; color: var(--kq-text-sub); margin-top: 4px; }
.kq-completion-progress {
  width: 100%;
  max-width: 360px;
  height: 8px;
  border-radius: 4px;
  background: var(--kq-surface);
  overflow: hidden;
  margin-bottom: 24px;
}
.kq-completion-progress-fill {
  height: 100%;
  border-radius: 4px;
  background: var(--kq-known);
  transition: width 1s cubic-bezier(0.33, 1, 0.68, 1);
}
.kq-missed-btn {
  display: flex;
  align-items: center;
  padding: 14px 28px;
  border-radius: 12px;
  background: #3a2a1a;
  color: var(--kq-review);
  border: none;
  gap: 8px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  margin-bottom: 12px;
}
.kq-primary-btn {
  display: flex;
  align-items: center;
  padding: 16px 32px;
  border-radius: 12px;
  background: var(--kq-primary);
  color: #fff;
  border: none;
  gap: 8px;
  font-size: 17px;
  font-weight: 600;
  cursor: pointer;
  margin-bottom: 16px;
}
.kq-done-btn {
  padding: 14px 32px;
  border-radius: 12px;
  border: 1px solid var(--kq-border);
  background: transparent;
  color: var(--kq-text);
  font-size: 17px;
  font-weight: 500;
  cursor: pointer;
}

/* ══════════════════════════════════════════════════════════
   TOC Mode
   ══════════════════════════════════════════════════════════ */
#kq-toc {
  flex-direction: column;
}
.kq-toc-url-row {
  display: flex;
  padding: 0 16px 12px;
  gap: 8px;
}
.kq-toc-url-input {
  flex: 1;
  height: 44px;
  border-radius: 10px;
  border: 1px solid var(--kq-border);
  background: var(--kq-surface);
  color: var(--kq-text);
  padding: 0 12px;
  font-size: 14px;
  font-family: inherit;
  outline: none;
}
.kq-toc-url-input:focus { border-color: var(--kq-purple); }
.kq-toc-load-btn {
  background: var(--kq-purple);
  height: 44px;
  padding: 0 18px;
  border-radius: 10px;
  border: none;
  color: #fff;
  font-weight: 600;
  font-size: 15px;
  cursor: pointer;
}
.kq-toc-list {
  flex: 1;
  overflow-y: auto;
  padding: 0 16px 40px;
  -webkit-overflow-scrolling: touch;
}
.kq-toc-card {
  display: flex;
  align-items: center;
  padding: 14px;
  border-radius: 14px;
  border: 1px solid var(--kq-border);
  background: var(--kq-surface);
  margin-bottom: 10px;
  cursor: pointer;
  transition: border-color 0.2s;
}
.kq-toc-card:hover { border-color: rgba(139,92,246,0.3); }
.kq-toc-card-icon {
  width: 42px; height: 42px;
  border-radius: 10px;
  background: rgba(139,92,246,0.1);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-right: 12px;
  flex-shrink: 0;
  font-size: 22px;
  color: var(--kq-purple);
}
.kq-toc-card-text { flex: 1; margin-right: 8px; }
.kq-toc-card-title { font-size: 15px; font-weight: 600; color: var(--kq-text); margin-bottom: 3px; }
.kq-toc-card-desc { font-size: 13px; color: var(--kq-text-sub); line-height: 1.4; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.kq-toc-chevron { color: var(--kq-text-sub); font-size: 18px; }

/* ── Bottom Sheet (mode picker) ───────────────────────── */
.kq-bottom-sheet-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: 2000;
  display: none;
  align-items: flex-end;
  justify-content: center;
}
.kq-bottom-sheet-overlay.open { display: flex; }
.kq-bottom-sheet {
  background: var(--kq-surface-solid);
  border-radius: 24px 24px 0 0;
  padding: 16px 20px 32px;
  width: 100%;
  max-width: 500px;
  animation: kq-sheet-up 0.3s ease;
}
@keyframes kq-sheet-up {
  from { transform: translateY(100%); }
  to   { transform: translateY(0); }
}
.kq-sheet-handle {
  width: 36px; height: 4px;
  background: rgba(255,255,255,0.2);
  border-radius: 2px;
  margin: 0 auto 16px;
}
.kq-sheet-title {
  font-size: 17px;
  font-weight: 700;
  color: var(--kq-text);
  text-align: center;
  margin-bottom: 4px;
}
.kq-sheet-subtitle {
  font-size: 13px;
  color: var(--kq-text-sub);
  text-align: center;
  margin-bottom: 16px;
}
.kq-sheet-option {
  display: flex;
  align-items: center;
  width: 100%;
  padding: 16px;
  border-radius: 14px;
  border: 1px solid var(--kq-border);
  background: transparent;
  color: var(--kq-text);
  cursor: pointer;
  gap: 12px;
  margin-bottom: 8px;
  font-size: 16px;
  font-weight: 600;
  font-family: inherit;
  transition: background 0.15s;
}
.kq-sheet-option:hover { background: rgba(255,255,255,0.04); }
.kq-sheet-option-icon { font-size: 22px; }
.kq-sheet-cancel {
  width: 100%;
  padding: 14px;
  border-radius: 14px;
  border: none;
  background: rgba(255,255,255,0.06);
  color: var(--kq-text-sub);
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  margin-top: 4px;
  font-family: inherit;
}

/* ══════════════════════════════════════════════════════════
   Explorer Page (study-explore.php)
   ══════════════════════════════════════════════════════════ */
.kq-explore-container {
  min-height: 100vh;
  background: var(--kq-bg);
  padding-bottom: 60px;
}
.kq-explore-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px;
  max-width: 700px;
  margin: 0 auto;
}
.kq-explore-title {
  font-size: 20px;
  font-weight: 700;
  color: var(--kq-text);
}
.kq-explore-subtitle {
  font-size: 14px;
  color: var(--kq-text-sub);
  line-height: 1.5;
  padding: 0 16px 16px;
  max-width: 700px;
  margin: 0 auto;
}
.kq-explore-list {
  max-width: 700px;
  margin: 0 auto;
  padding: 0 16px;
}
.kq-explore-card {
  display: flex;
  align-items: center;
  padding: 14px;
  border-radius: 14px;
  border: 1px solid var(--kq-border);
  background: var(--kq-surface);
  margin-bottom: 10px;
  cursor: pointer;
  transition: border-color 0.2s, transform 0.2s;
  text-decoration: none;
}
.kq-explore-card:hover {
  border-color: rgba(255,255,255,0.12);
  transform: translateY(-2px);
}
.kq-explore-card-icon {
  width: 42px; height: 42px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-right: 12px;
  flex-shrink: 0;
  font-size: 20px;
}
.kq-explore-card-text { flex: 1; margin-right: 8px; }
.kq-explore-card-title { font-size: 15px; font-weight: 600; color: var(--kq-text); margin-bottom: 3px; }
.kq-explore-card-desc { font-size: 13px; color: var(--kq-text-sub); line-height: 1.4; display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden; }
.kq-explore-chevron { color: var(--kq-text-sub); font-size: 18px; }

/* ── Responsive ───────────────────────────────────────── */
@media (max-width: 480px) {
  .kq-card { padding: 60px 20px 100px; }
  .kq-card-q { font-size: 20px; }
  .kq-card-a { font-size: 18px; }
  .kq-question-text { font-size: 18px; }
  .kq-tf-statement { font-size: 20px; }
  .kq-cover-title { font-size: 24px; }
  .kq-hero-pct { font-size: 48px; }
}

/* ── TOC empty/center states ──────────────────────────── */
.kq-center-state {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 32px;
  text-align: center;
  gap: 12px;
}
.kq-center-state-icon { font-size: 48px; color: var(--kq-text-sub); }
.kq-center-state-text { font-size: 15px; color: var(--kq-text-sub); line-height: 1.5; }

/* ── Light mode overrides ── */
[data-theme="light"] .kq-card-back { background: #e6f5ef; }
[data-theme="light"] .kq-stat-box.known { background: #e6f5ef; }
[data-theme="light"] .kq-stat-box.review-box { background: #fef3cd; }
[data-theme="light"] .kq-btn-review { background: #fef3cd; }
[data-theme="light"] .kq-btn-known { background: #e6f5ef; }
[data-theme="light"] .kq-completion-icon { background: #e6f5ef; }
[data-theme="light"] .kq-missed-btn { background: #fef3cd; }
[data-theme="light"] .kq-choice-letter { background: var(--kv-btn-ghost-bg); }
[data-theme="light"] .kq-sheet-handle { background: var(--kv-sheet-handle); }
[data-theme="light"] .kq-sheet-option:hover { background: var(--kv-sheet-option-hover); }
[data-theme="light"] .kq-sheet-cancel { background: var(--kv-sheet-cancel); }