/* ===== Reset & Base ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --primary: #6C63FF;
  --primary-light: #A89CFF;
  --primary-dark: #4B44CC;
  --secondary: #FF6584;
  --accent: #43D9AD;
  --bg: #0F0F1A;
  --bg2: #1A1A2E;
  --bg3: #16213E;
  --card: #1E1E35;
  --card2: #252542;
  --text: #EAEAF5;
  --text2: #A0A0C0;
  --text3: #6060A0;
  --border: #2E2E50;
  --success: #43D9AD;
  --danger: #FF6584;
  --warning: #FFD166;
  --shadow: 0 8px 32px rgba(0,0,0,0.4);
  --radius: 16px;
  --radius-sm: 10px;
  --transition: 0.3s cubic-bezier(0.4,0,0.2,1);
}

html { scroll-behavior: smooth; }

body {
  font-family: 'Segoe UI', 'Noto Sans KR', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  overflow-x: hidden;
}

/* ===== Background Particles ===== */
.bg-particles {
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  pointer-events: none;
  z-index: 0;
  overflow: hidden;
}
.particle {
  position: absolute;
  border-radius: 50%;
  opacity: 0.08;
  animation: floatParticle linear infinite;
}

@keyframes floatParticle {
  0% { transform: translateY(100vh) rotate(0deg); opacity: 0; }
  10% { opacity: 0.08; }
  90% { opacity: 0.08; }
  100% { transform: translateY(-100px) rotate(720deg); opacity: 0; }
}

/* ===== App Layout ===== */
#app {
  position: relative;
  z-index: 1;
  max-width: 900px;
  margin: 0 auto;
  padding: 20px 16px 60px;
}

/* ===== Header ===== */
.app-header {
  text-align: center;
  padding: 40px 0 32px;
}

.logo-icon {
  font-size: 3rem;
  margin-bottom: 10px;
  display: block;
  animation: bounce 2s ease infinite;
}

@keyframes bounce {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
}

.app-title {
  font-size: 2.2rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--primary-light), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 6px;
}

.app-subtitle {
  color: var(--text2);
  font-size: 0.95rem;
}

/* ===== Day Badge ===== */
.day-info {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  margin: 20px 0 28px;
  flex-wrap: wrap;
}

.day-badge {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: white;
  padding: 8px 22px;
  border-radius: 50px;
  font-weight: 700;
  font-size: 1rem;
  box-shadow: 0 4px 15px rgba(108,99,255,0.4);
}

.date-badge {
  background: var(--card);
  border: 1px solid var(--border);
  color: var(--text2);
  padding: 8px 18px;
  border-radius: 50px;
  font-size: 0.88rem;
}

/* ===== Day Selector ===== */
.day-selector-section {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 20px;
  margin-bottom: 24px;
}

.day-selector-label {
  font-size: 0.85rem;
  color: var(--text2);
  margin-bottom: 12px;
  display: block;
}

.day-selector-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.day-btn {
  width: 36px;
  height: 36px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--bg2);
  color: var(--text2);
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
}

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

.day-btn.active {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: white;
  border-color: var(--primary);
  box-shadow: 0 3px 10px rgba(108,99,255,0.5);
}

.day-btn.completed {
  border-color: var(--accent);
  color: var(--accent);
}

/* ===== Tab Navigation ===== */
.tab-nav {
  display: flex;
  gap: 6px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 50px;
  padding: 6px;
  margin-bottom: 28px;
}

.tab-btn {
  flex: 1;
  padding: 10px 16px;
  border-radius: 50px;
  border: none;
  background: transparent;
  color: var(--text2);
  font-size: 0.88rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
}

.tab-btn.active {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: white;
  box-shadow: 0 3px 12px rgba(108,99,255,0.4);
}

.tab-btn:hover:not(.active) {
  color: var(--text);
  background: var(--card2);
}

/* ===== Section Panels ===== */
.panel { display: none; }
.panel.active { display: block; animation: fadeIn 0.3s ease; }

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

/* ===== Word List Panel ===== */
.word-list-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
}

.word-count-badge {
  background: var(--card2);
  border: 1px solid var(--border);
  color: var(--text2);
  padding: 4px 14px;
  border-radius: 50px;
  font-size: 0.82rem;
}

.word-cards-grid {
  display: grid;
  gap: 14px;
}

.word-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 24px;
  cursor: pointer;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.word-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 4px;
  height: 100%;
  background: linear-gradient(180deg, var(--primary), var(--accent));
  border-radius: 4px 0 0 4px;
}

.word-card:hover {
  transform: translateX(4px);
  border-color: var(--primary);
  box-shadow: var(--shadow);
}

.word-card.known {
  background: rgba(67,217,173,0.08);
  border-color: rgba(67,217,173,0.3);
}

.word-card.known::before {
  background: var(--accent);
}

.word-header {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 6px;
}

.word-text {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--text);
}

.word-pron {
  font-size: 0.85rem;
  color: var(--primary-light);
  font-style: italic;
}

.word-pos-badge {
  margin-left: auto;
  background: rgba(108,99,255,0.15);
  color: var(--primary-light);
  padding: 2px 10px;
  border-radius: 50px;
  font-size: 0.75rem;
}

.word-meaning {
  font-size: 1rem;
  color: var(--accent);
  font-weight: 600;
  margin-bottom: 8px;
}

.word-example {
  font-size: 0.9rem;
  color: var(--text2);
  line-height: 1.5;
}

.word-example-ko {
  font-size: 0.82rem;
  color: var(--text3);
  margin-top: 3px;
}

.word-actions {
  display: flex;
  gap: 8px;
  margin-top: 12px;
}

.btn-know {
  display: flex;
  align-items: center;
  gap: 5px;
  padding: 6px 14px;
  border-radius: 50px;
  border: 1px solid var(--accent);
  background: transparent;
  color: var(--accent);
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}

.btn-know:hover, .btn-know.active {
  background: var(--accent);
  color: var(--bg);
}

.btn-speak {
  display: flex;
  align-items: center;
  gap: 5px;
  padding: 6px 14px;
  border-radius: 50px;
  border: 1px solid var(--primary-light);
  background: transparent;
  color: var(--primary-light);
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}

.btn-speak:hover {
  background: var(--primary-light);
  color: var(--bg);
}

/* ===== Flashcard Panel ===== */
.flashcard-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 24px;
}

.flashcard-progress {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 10px;
}

.progress-bar-wrap {
  flex: 1;
  height: 6px;
  background: var(--card2);
  border-radius: 50px;
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), var(--accent));
  border-radius: 50px;
  transition: width 0.4s ease;
}

.progress-text {
  font-size: 0.85rem;
  color: var(--text2);
  white-space: nowrap;
}

.flashcard-wrap {
  width: 100%;
  max-width: 540px;
  perspective: 1200px;
}

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

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

.card-face {
  position: absolute;
  inset: 0;
  border-radius: var(--radius);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  padding: 36px;
  box-shadow: var(--shadow);
}

.card-front {
  background: linear-gradient(135deg, var(--bg2), var(--card));
  border: 1px solid var(--border);
}

.card-back {
  background: linear-gradient(135deg, rgba(108,99,255,0.2), rgba(67,217,173,0.1));
  border: 1px solid rgba(108,99,255,0.4);
  transform: rotateY(180deg);
}

.card-hint {
  position: absolute;
  top: 16px;
  right: 20px;
  font-size: 0.75rem;
  color: var(--text3);
}

.card-word {
  font-size: 2.4rem;
  font-weight: 800;
  color: var(--text);
  text-align: center;
  margin-bottom: 12px;
}

.card-pron {
  font-size: 1rem;
  color: var(--primary-light);
  font-style: italic;
  margin-bottom: 8px;
}

.card-tag {
  background: rgba(108,99,255,0.2);
  color: var(--primary-light);
  padding: 4px 14px;
  border-radius: 50px;
  font-size: 0.78rem;
}

.card-meaning {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--accent);
  text-align: center;
  margin-bottom: 14px;
}

.card-example {
  font-size: 0.92rem;
  color: var(--text2);
  text-align: center;
  line-height: 1.6;
}

.card-example-ko {
  font-size: 0.82rem;
  color: var(--text3);
  text-align: center;
  margin-top: 6px;
}

.flashcard-controls {
  display: flex;
  gap: 12px;
  width: 100%;
  max-width: 540px;
}

.fc-btn {
  flex: 1;
  padding: 14px;
  border-radius: var(--radius-sm);
  border: none;
  font-size: 0.95rem;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}

.fc-btn-wrong {
  background: rgba(255,101,132,0.15);
  color: var(--danger);
  border: 1px solid rgba(255,101,132,0.3);
}
.fc-btn-wrong:hover { background: var(--danger); color: white; }

.fc-btn-correct {
  background: rgba(67,217,173,0.15);
  color: var(--accent);
  border: 1px solid rgba(67,217,173,0.3);
}
.fc-btn-correct:hover { background: var(--accent); color: var(--bg); }

.fc-btn-flip {
  background: rgba(108,99,255,0.15);
  color: var(--primary-light);
  border: 1px solid rgba(108,99,255,0.3);
}
.fc-btn-flip:hover { background: var(--primary); color: white; }

.flashcard-result {
  display: none;
  text-align: center;
  padding: 40px 20px;
  animation: fadeIn 0.4s ease;
}

.result-emoji { font-size: 4rem; margin-bottom: 16px; }
.result-title { font-size: 1.6rem; font-weight: 800; margin-bottom: 8px; }
.result-subtitle { color: var(--text2); margin-bottom: 24px; }

.result-stats {
  display: flex;
  gap: 16px;
  justify-content: center;
  margin-bottom: 24px;
  flex-wrap: wrap;
}

.stat-box {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 16px 28px;
  text-align: center;
}

.stat-num { font-size: 2rem; font-weight: 800; }
.stat-label { font-size: 0.8rem; color: var(--text2); margin-top: 4px; }
.stat-correct .stat-num { color: var(--accent); }
.stat-wrong .stat-num { color: var(--danger); }

.btn-restart {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: white;
  border: none;
  padding: 14px 32px;
  border-radius: 50px;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: 0 4px 15px rgba(108,99,255,0.4);
}

.btn-restart:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(108,99,255,0.5); }

/* ===== Quiz Panel ===== */
.quiz-section { max-width: 600px; margin: 0 auto; }

.quiz-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
}

.quiz-score {
  display: flex;
  align-items: center;
  gap: 6px;
  background: var(--card);
  border: 1px solid var(--border);
  padding: 6px 16px;
  border-radius: 50px;
  font-size: 0.9rem;
  font-weight: 700;
}

.score-icon { font-size: 1rem; }

.quiz-progress { font-size: 0.85rem; color: var(--text2); }

.quiz-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  margin-bottom: 20px;
  box-shadow: var(--shadow);
}

.quiz-type-badge {
  display: inline-block;
  background: rgba(108,99,255,0.2);
  color: var(--primary-light);
  padding: 4px 14px;
  border-radius: 50px;
  font-size: 0.78rem;
  margin-bottom: 20px;
}

.quiz-question {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 6px;
  text-align: center;
}

.quiz-sub {
  font-size: 0.88rem;
  color: var(--text2);
  text-align: center;
  margin-bottom: 28px;
}

.quiz-options {
  display: grid;
  gap: 10px;
}

.option-btn {
  padding: 14px 20px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--bg2);
  color: var(--text);
  font-size: 0.95rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
  text-align: left;
  display: flex;
  align-items: center;
  gap: 12px;
}

.option-label {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--card2);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.78rem;
  font-weight: 700;
  flex-shrink: 0;
}

.option-btn:hover:not(:disabled) {
  background: rgba(108,99,255,0.1);
  border-color: var(--primary);
  transform: translateX(4px);
}

.option-btn.correct {
  background: rgba(67,217,173,0.15);
  border-color: var(--accent);
  color: var(--accent);
}

.option-btn.wrong {
  background: rgba(255,101,132,0.15);
  border-color: var(--danger);
  color: var(--danger);
}

.option-btn:disabled { cursor: default; }

.quiz-feedback {
  padding: 14px 18px;
  border-radius: var(--radius-sm);
  margin-top: 16px;
  font-size: 0.9rem;
  font-weight: 500;
  display: none;
  align-items: flex-start;
  gap: 10px;
}

.quiz-feedback.show { display: flex; animation: fadeIn 0.2s ease; }
.quiz-feedback.correct-fb { background: rgba(67,217,173,0.12); color: var(--accent); border: 1px solid rgba(67,217,173,0.3); }
.quiz-feedback.wrong-fb { background: rgba(255,101,132,0.12); color: var(--danger); border: 1px solid rgba(255,101,132,0.3); }

.btn-next-quiz {
  width: 100%;
  padding: 14px;
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: white;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
  display: none;
}

.btn-next-quiz.show { display: block; animation: fadeIn 0.2s ease; }
.btn-next-quiz:hover { opacity: 0.9; transform: translateY(-2px); }

/* ===== Progress Panel ===== */
.progress-section { max-width: 700px; margin: 0 auto; }

.progress-overview {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  margin-bottom: 28px;
}

.overview-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  text-align: center;
}

.overview-icon { font-size: 2rem; margin-bottom: 8px; }
.overview-num { font-size: 1.8rem; font-weight: 800; margin-bottom: 4px; }
.overview-label { font-size: 0.78rem; color: var(--text2); }
.ov-green .overview-num { color: var(--accent); }
.ov-purple .overview-num { color: var(--primary-light); }
.ov-orange .overview-num { color: var(--warning); }

.heatmap-section {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 20px;
}

.heatmap-title {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 16px;
  color: var(--text);
}

.heatmap-grid {
  display: grid;
  grid-template-columns: repeat(10, 1fr);
  gap: 6px;
}

.heatmap-cell {
  aspect-ratio: 1;
  border-radius: 5px;
  background: var(--bg2);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.68rem;
  color: var(--text3);
  cursor: pointer;
  transition: var(--transition);
  position: relative;
}

.heatmap-cell:hover { transform: scale(1.15); z-index: 2; }
.heatmap-cell.today { border-color: var(--primary); }
.heatmap-cell.visited { background: rgba(108,99,255,0.25); border-color: rgba(108,99,255,0.4); color: var(--primary-light); }
.heatmap-cell.completed-day { background: rgba(67,217,173,0.2); border-color: rgba(67,217,173,0.4); color: var(--accent); }

.daily-progress-list {
  display: grid;
  gap: 10px;
}

.progress-item {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 14px 18px;
  display: flex;
  align-items: center;
  gap: 14px;
  cursor: pointer;
  transition: var(--transition);
}

.progress-item:hover {
  border-color: var(--primary);
  background: var(--card2);
}

.pi-day {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  background: var(--bg2);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.85rem;
  flex-shrink: 0;
}

.pi-day.today { background: var(--primary); color: white; border-color: var(--primary); }
.pi-day.done { background: rgba(67,217,173,0.15); color: var(--accent); border-color: var(--accent); }

.pi-info { flex: 1; }
.pi-title { font-size: 0.9rem; font-weight: 600; margin-bottom: 4px; }
.pi-bar { height: 4px; background: var(--bg2); border-radius: 50px; overflow: hidden; }
.pi-fill { height: 100%; background: linear-gradient(90deg, var(--primary), var(--accent)); border-radius: 50px; }

.pi-pct {
  font-size: 0.82rem;
  color: var(--text2);
  font-weight: 600;
  flex-shrink: 0;
}

/* ===== Responsive ===== */
@media (max-width: 600px) {
  .app-title { font-size: 1.7rem; }
  .flashcard { height: 270px; }
  .card-word { font-size: 1.9rem; }
  .card-meaning { font-size: 1.3rem; }
  .progress-overview { grid-template-columns: 1fr 1fr; }
  .tab-btn { font-size: 0.78rem; padding: 9px 8px; }
  .heatmap-grid { grid-template-columns: repeat(6, 1fr); }
}