/* ============================================================
   BASIC ENGLISH APP — Styles
   ============================================================ */

:root {
  --bg: #f8f9fa;
  --surface: #ffffff;
  --surface2: #f0f2f5;
  --text: #1a1a2e;
  --text2: #6c757d;
  --border: #dee2e6;
  --primary: #4f8cff;
  --primary-hover: #3a6fd8;
  --success: #2ecc71;
  --danger: #e74c3c;
  --warning: #f39c12;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 2px 8px rgba(0,0,0,.06);
  --shadow-lg: 0 4px 24px rgba(0,0,0,.1);
  --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  --font-mono: 'SF Mono', 'Cascadia Code', 'Consolas', monospace;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
}

/* ---- NAV ---- */
.navbar {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
  height: 60px;
  display: flex;
  align-items: center;
  gap: 8px;
  position: sticky;
  top: 0;
  z-index: 100;
}

.navbar .brand {
  font-weight: 700;
  font-size: 1.1rem;
  margin-right: 24px;
  color: var(--text);
  text-decoration: none;
  letter-spacing: -.02em;
}

.navbar .brand span { color: var(--primary); }

.nav-btn {
  background: none;
  border: none;
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  font-size: .9rem;
  color: var(--text2);
  cursor: pointer;
  transition: all .15s;
  font-family: var(--font);
}

.nav-btn:hover { background: var(--surface2); color: var(--text); }
.nav-btn.active { background: var(--primary); color: #fff; }

/* ---- MAIN ---- */
.main-content {
  max-width: 960px;
  margin: 0 auto;
  padding: 24px 20px;
}

/* ---- HOME ---- */
.home-layout { text-align: center; }

.home-hero {
  padding: 48px 0 32px;
}

.home-hero h1 {
  font-size: 2.5rem;
  font-weight: 800;
  letter-spacing: -.03em;
  margin-bottom: 8px;
}

.home-subtitle {
  font-size: 1.1rem;
  color: var(--text2);
  margin-bottom: 16px;
}

.home-desc {
  max-width: 600px;
  margin: 0 auto;
  color: var(--text2);
  font-size: .95rem;
  line-height: 1.7;
}

.home-cards {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin: 40px 0;
}

.home-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px 28px;
  cursor: pointer;
  transition: all .2s;
  text-align: left;
}

.home-card:hover {
  border-color: var(--primary);
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

.home-card-icon { font-size: 2rem; margin-bottom: 12px; }
.home-card h2 { font-size: 1.2rem; margin-bottom: 8px; }
.home-card p { font-size: .9rem; color: var(--text2); line-height: 1.6; }
.home-card-link {
  display: inline-block;
  margin-top: 12px;
  color: var(--primary);
  font-weight: 600;
  font-size: .9rem;
}

.home-stats {
  display: flex;
  justify-content: center;
  gap: 32px;
  margin-top: 32px;
  padding: 24px 0;
}

.stat { text-align: center; }
.stat-num {
  display: block;
  font-size: 1.8rem;
  font-weight: 800;
  color: var(--primary);
}
.stat-label { font-size: .85rem; color: var(--text2); }

/* ---- CHAT ---- */
.chat-layout {
  display: flex;
  flex-direction: row;
  height: calc(100vh - 108px);
  max-height: 750px;
  gap: 16px;
}

.chat-main {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.chat-settings-bar {
  display: flex;
  gap: 8px;
  padding-bottom: 12px;
  flex-wrap: wrap;
}

.btn-scenario {
  margin-left: auto;
}

/* ---- SCENARIO SIDEBAR ---- */
.scenario-sidebar {
  width: 260px;
  flex-shrink: 0;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.scenario-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  font-weight: 600;
  font-size: .95rem;
  background: var(--surface2);
}

.scenario-close {
  display: none;
  border: none;
  background: transparent;
  font-size: 1.3rem;
  cursor: pointer;
  color: var(--text2);
  line-height: 1;
  padding: 0 4px;
}

.scenario-close:hover {
  color: var(--text);
}

.scenario-list {
  flex: 1;
  overflow-y: auto;
  padding: 8px 0;
}

.scenario-category {
  padding: 10px 16px 6px;
  font-size: .75rem;
  font-weight: 700;
  color: var(--text2);
  text-transform: uppercase;
  letter-spacing: .5px;
  background: var(--surface);
  position: sticky;
  top: 0;
}

.scenario-item {
  padding: 10px 16px;
  cursor: pointer;
  font-size: .88rem;
  border-left: 3px solid transparent;
  transition: all .15s;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.scenario-item:hover {
  background: var(--surface2);
  border-left-color: var(--primary);
}

.scenario-item-en {
  font-size: .75rem;
  color: var(--text2);
}

/* ---- CHAT DIVIDER ---- */
.chat-divider {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 8px 0;
}

.divider-line {
  flex: 1;
  height: 1px;
  background: var(--border);
}

.divider-text {
  font-size: .8rem;
  color: var(--text2);
  font-weight: 600;
  white-space: nowrap;
}

/* ---- MOBILE RESPONSIVE ---- */
@media (max-width: 900px) {
  .chat-layout {
    flex-direction: column;
    position: relative;
  }

  .scenario-sidebar {
    position: fixed;
    top: 60px;
    right: 0;
    bottom: 0;
    width: 280px;
    max-width: 85vw;
    z-index: 200;
    border-radius: 0;
    border-left: 1px solid var(--border);
    transform: translateX(100%);
    transition: transform .25s ease;
    box-shadow: -4px 0 24px rgba(0,0,0,.1);
  }

  .scenario-sidebar.open {
    transform: translateX(0);
  }

  .scenario-close {
    display: block;
  }

  .btn-scenario {
    margin-left: 0;
  }
}

@media (min-width: 901px) {
  .btn-scenario {
    display: none;
  }
}

.chat-settings {
  background: var(--surface2);
  border-radius: var(--radius);
  padding: 16px;
  margin-bottom: 12px;
}

.form-group {
  margin-bottom: 10px;
}

.form-group label {
  display: block;
  font-size: .8rem;
  font-weight: 600;
  color: var(--text2);
  margin-bottom: 4px;
}

.form-group input {
  width: 100%;
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-family: var(--font);
  font-size: .9rem;
  background: var(--surface);
}

.provider-presets {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
}

.provider-presets .btn {
  font-size: .78rem;
  padding: 4px 10px;
}

.chat-messages {
  flex: 1;
  overflow-y: auto;
  padding: 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 12px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.chat-welcome {
  text-align: center;
  padding: 48px 20px;
  color: var(--text2);
}

.chat-welcome p { margin-bottom: 8px; }
.chat-welcome .hint { font-size: .85rem; opacity: .7; }

.chat-message {
  position: relative;
  max-width: 85%;
  padding: 12px 32px 12px 16px;
  border-radius: var(--radius);
  font-size: .93rem;
  line-height: 1.5;
}

.msg-sound {
  position: absolute;
  top: 8px;
  right: 8px;
  cursor: pointer;
  font-size: .75rem;
  opacity: .35;
  transition: opacity .15s, transform .15s;
  user-select: none;
}

.msg-sound:hover { opacity: 1; transform: scale(1.2); }

.chat-message.user {
  align-self: flex-end;
  background: var(--primary);
  color: #fff;
  border-bottom-right-radius: 4px;
}

.chat-message.assistant {
  align-self: flex-start;
  background: var(--surface2);
  border-bottom-left-radius: 4px;
}

.msg-violations {
  font-size: .75rem;
  color: var(--warning);
  margin-top: 6px;
  padding-top: 6px;
  border-top: 1px solid rgba(255,255,255,.2);
}

.chat-message.user .msg-violations { color: #ffd700; }

.chat-input-area { }

.chat-validation {
  font-size: .8rem;
  padding: 4px 0;
  min-height: 24px;
}

.chat-validation.ok { color: var(--success); }
.chat-validation.warning { color: var(--warning); }

.bad-word {
  display: inline-block;
  background: #fff3cd;
  color: #856404;
  padding: 0 6px;
  border-radius: 3px;
  font-size: .8rem;
  font-weight: 600;
}

.chat-input-row {
  display: flex;
  gap: 8px;
}

.chat-input-row textarea {
  flex: 1;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-family: var(--font);
  font-size: .93rem;
  resize: none;
  background: var(--surface);
}

.chat-input-row textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(79,140,255,.15);
}

/* ---- BUTTONS ---- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--text);
  font-size: .85rem;
  font-family: var(--font);
  cursor: pointer;
  transition: all .15s;
  white-space: nowrap;
}

.btn:hover { background: var(--surface2); }
.btn:disabled { opacity: .5; cursor: default; }
.btn-sm { padding: 5px 12px; font-size: .8rem; }
.btn-primary { background: var(--primary); color: #fff; border-color: var(--primary); }
.btn-primary:hover { background: var(--primary-hover); }

/* ---- TEACHING ---- */
.teaching-layout { }

.teaching-tabs {
  display: flex;
  gap: 4px;
  margin-bottom: 20px;
  background: var(--surface2);
  border-radius: var(--radius);
  padding: 4px;
}

.tab-btn {
  flex: 1;
  padding: 10px 16px;
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--text2);
  font-size: .9rem;
  font-family: var(--font);
  cursor: pointer;
  transition: all .15s;
}

.tab-btn.active {
  background: var(--surface);
  color: var(--text);
  font-weight: 600;
  box-shadow: var(--shadow);
}

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

/* ---- WORD CARDS ---- */
.cards-section { }

.cards-controls { margin-bottom: 16px; }

.cards-search input {
  width: 100%;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-family: var(--font);
  font-size: .93rem;
  margin-bottom: 10px;
  background: var(--surface);
}

.cards-search input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(79,140,255,.15);
}

.cards-categories {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.cat-btn {
  padding: 5px 14px;
  border: 1px solid var(--border);
  border-radius: 20px;
  background: var(--surface);
  color: var(--text2);
  font-size: .8rem;
  font-family: var(--font);
  cursor: pointer;
  transition: all .15s;
}

.cat-btn:hover { border-color: var(--cat-color, var(--primary)); color: var(--text); }
.cat-btn.active {
  background: var(--cat-color, var(--primary));
  border-color: var(--cat-color, var(--primary));
  color: #fff;
}

.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
  gap: 8px;
}

.word-card {
  background: var(--surface);
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 12px 8px;
  text-align: center;
  transition: all .15s;
}

.word-card:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow);
}

.word-card-word {
  font-size: .95rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.word-card-cat {
  display: inline-block;
  font-size: .65rem;
  color: #fff;
  padding: 2px 8px;
  border-radius: 10px;
  font-weight: 500;
}

.cards-pagination {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 12px;
  margin-top: 16px;
}

.page-info { font-size: .85rem; color: var(--text2); }

.empty-state {
  text-align: center;
  padding: 48px;
  color: var(--text2);
}

/* ---- WORD MODAL ---- */
.word-modal {
  position: fixed;
  inset: 0;
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
}

.word-modal-overlay {
  position: absolute;
  inset: 0;
  background: rgba(0,0,0,.4);
  animation: fadeIn .2s;
}

.word-modal-content {
  position: relative;
  background: var(--surface);
  border-radius: 16px;
  padding: 40px 48px;
  text-align: center;
  box-shadow: 0 8px 40px rgba(0,0,0,.2);
  z-index: 1;
  animation: popIn .25s cubic-bezier(.2,1.3,.4,1);
  min-width: 240px;
}

.word-modal-close {
  position: absolute;
  top: 10px;
  right: 14px;
  background: none;
  border: none;
  font-size: 1.6rem;
  cursor: pointer;
  color: var(--text2);
  padding: 4px 8px;
  line-height: 1;
}

.word-modal-close:hover { color: var(--text); }

.word-modal-word {
  font-size: 2rem;
  font-weight: 800;
  margin-bottom: 8px;
  line-height: 1.2;
}

.word-sound {
  display: inline-block;
  cursor: pointer;
  font-size: 1.2rem;
  margin-right: 8px;
  color: var(--primary);
  transition: transform .15s;
  vertical-align: middle;
}

.word-sound:hover { transform: scale(1.25); }
.word-sound:active { transform: scale(.95); }

.word-modal-cn {
  font-size: 1.4rem;
  color: var(--primary);
  margin-bottom: 16px;
  font-weight: 600;
}

.word-modal-cat {
  display: inline-block;
  font-size: .75rem;
  color: #fff;
  padding: 4px 14px;
  border-radius: 12px;
  font-weight: 500;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes popIn {
  from { transform: scale(.8); opacity: 0; }
  to { transform: scale(1); opacity: 1; }
}

/* ---- EXERCISES ---- */
.exercises-section { }

.exercises-header { margin-bottom: 20px; }
.exercises-header h3 { font-size: 1.1rem; margin-bottom: 4px; }
.exercises-header p { font-size: .9rem; color: var(--text2); }

.exercise-progress {
  margin-top: 8px;
  font-size: .85rem;
  color: var(--primary);
  font-weight: 600;
}

.exercise-selector {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 16px;
}

.ex-btn {
  padding: 6px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  font-size: .82rem;
  font-family: var(--font);
  cursor: pointer;
  transition: all .15s;
  color: var(--text2);
}

.ex-btn:hover { border-color: var(--primary); color: var(--text); }
.ex-btn.active { background: var(--primary); color: #fff; border-color: var(--primary); }

.exercise-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
}

.ex-title { font-size: 1rem; font-weight: 700; margin-bottom: 4px; }
.ex-desc { font-size: .85rem; color: var(--text2); margin-bottom: 20px; }

.ex-question {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 16px;
  line-height: 1.5;
}

.ex-input-row {
  display: flex;
  gap: 8px;
}

.ex-input-row input {
  flex: 1;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-family: var(--font);
  font-size: .95rem;
  background: var(--surface);
}

.ex-input-row input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(79,140,255,.15);
}

.ex-feedback {
  margin-top: 16px;
  font-size: .95rem;
  font-weight: 600;
  white-space: pre-line;
}

.ex-correct { color: var(--success); }
.ex-wrong { color: var(--danger); }

/* ---- REFERENCE ---- */
.reference-section { }

.reference-section h3 {
  font-size: 1.1rem;
  margin-bottom: 20px;
}

.ref-category {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 22px;
  margin-bottom: 12px;
}

.ref-category h4 {
  font-size: .95rem;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--primary);
}

.ref-category p {
  font-size: .88rem;
  line-height: 1.6;
  color: var(--text2);
}

.ref-category strong { color: var(--text); }
.ref-category em { color: var(--text2); }

/* ---- SPACED REPETITION ---- */
.sr-section { }
.sr-header { margin-bottom: 16px; }
.sr-header h3 { font-size: 1.1rem; margin-bottom: 4px; }
.sr-header p { font-size: .9rem; color: var(--text2); }

.sr-stats {
  display: flex;
  gap: 16px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.sr-stat {
  flex: 1;
  min-width: 80px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 12px;
  text-align: center;
}

.sr-stat-num {
  display: block;
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--primary);
}

.sr-stat-label { font-size: .75rem; color: var(--text2); }

.sr-actions {
  display: flex;
  gap: 8px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.sr-progress {
  height: 6px;
  background: var(--surface2);
  border-radius: 3px;
  margin-bottom: 8px;
  overflow: hidden;
}

.sr-progress-fill {
  height: 100%;
  background: var(--primary);
  border-radius: 3px;
  transition: width .3s;
}

.sr-progress-text {
  text-align: center;
  font-size: .82rem;
  color: var(--text2);
  margin-bottom: 20px;
}

.sr-card {
  position: relative;
  background: var(--surface);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  padding: 48px 32px;
  text-align: center;
  margin-bottom: 20px;
}

.sr-card-word {
  font-size: 2.2rem;
  font-weight: 800;
  margin-bottom: 12px;
  line-height: 1.3;
}

.sr-card-word .word-sound { font-size: 1.4rem; }

.sr-card-cn {
  font-size: 1.3rem;
  color: var(--primary);
  margin-bottom: 8px;
  font-weight: 600;
}

.sr-card-level {
  font-size: .8rem;
  color: var(--text2);
}

.sr-buttons {
  display: flex;
  gap: 12px;
  justify-content: center;
}

.sr-btn-yes {
  background: var(--success) !important;
  color: #fff !important;
  border-color: var(--success) !important;
  font-size: 1.1rem !important;
  padding: 14px 36px !important;
  border-radius: 12px !important;
}

.sr-btn-no {
  background: var(--danger) !important;
  color: #fff !important;
  border-color: var(--danger) !important;
  font-size: 1.1rem !important;
  padding: 14px 36px !important;
  border-radius: 12px !important;
}

.sr-btn-yes:hover { opacity: .85; }
.sr-btn-no:hover { opacity: .85; }

/* Card feedback animations */
.sr-card-known {
  border-color: var(--success) !important;
  animation: pulseKnown .45s ease;
}

.sr-card-unknown {
  border-color: var(--danger) !important;
  animation: pulseUnknown .45s ease;
}

.sr-card-feedback {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%,-50%);
  font-size: 3rem;
  font-weight: 800;
  opacity: .25;
  pointer-events: none;
}

.sr-card-known .sr-card-feedback { color: var(--success); }
.sr-card-unknown .sr-card-feedback { color: var(--danger); }

@keyframes pulseKnown {
  0% { background: #e8f5e9; transform: scale(1); }
  40% { background: #c8e6c9; transform: scale(1.015); }
  100% { background: var(--surface); transform: scale(1); }
}

@keyframes pulseUnknown {
  0% { background: #ffebee; transform: scale(1); }
  40% { background: #ffcdd2; transform: scale(1.015); }
  100% { background: var(--surface); transform: scale(1); }
}

.sr-summary { text-align: center; padding: 24px; }
.sr-summary h3 { font-size: 1.3rem; margin-bottom: 20px; }

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

.sr-summary-stat {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 24px;
  text-align: center;
}

.sr-summary-num {
  display: block;
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--primary);
}

.sr-summary-stat:first-child .sr-summary-num { color: var(--success); }
.sr-summary-stat:nth-child(2) .sr-summary-num { color: var(--danger); }

/* ---- LOADING ---- */
.loading-dots::after {
  content: '';
  animation: dots 1.5s infinite;
}

@keyframes dots {
  0% { content: ''; }
  25% { content: '.'; }
  50% { content: '..'; }
  75% { content: '...'; }
}

.loading-msg { opacity: .6; }

/* ---- RESPONSIVE ---- */
@media (max-width: 640px) {
  .home-cards { grid-template-columns: 1fr; }
  .home-hero h1 { font-size: 1.8rem; }
  .home-stats { flex-wrap: wrap; gap: 16px; }
  .cards-grid { grid-template-columns: repeat(auto-fill, minmax(100px, 1fr)); }
  .exercise-selector { flex-direction: column; }
  .teaching-tabs { flex-direction: column; }
  .chat-message { max-width: 95%; }
  .navbar { padding: 0 12px; overflow-x: auto; }
}

/* ---- SPEECH UNAVAILABLE (Android WebView, WeChat browser, etc.) ---- */
body.speech-unavailable .msg-sound,
body.speech-unavailable .word-sound {
  display: none !important;
}