/* ========== TEF Master - Global Design System ========== */
:root {
  --primary: #1a365d;
  --primary-light: #3b82f6;
  --primary-bg: #eff6ff;
  --accent: #8b5cf6;
  --accent-light: #a78bfa;
  --success: #10b981;
  --warning: #f59e0b;
  --danger: #ef4444;
  --text: #1e293b;
  --text-light: #475569;
  --bg: #f8fafc;
  --card: #ffffff;
  --border: #e2e8f0;
  --radius: 12px;
  --shadow: 0 2px 12px rgba(0,0,0,.06);
  --font: 'Segoe UI', system-ui, -apple-system, sans-serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { font-family: var(--font); background: var(--bg); color: var(--text); line-height: 1.7; }

/* ---- Navigation ---- */
.nav {
  background: var(--primary);
  padding: 0;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 10px rgba(0,0,0,.2);
}
.nav-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 1rem;
}
.nav-brand {
  color: #fff;
  font-weight: 800;
  font-size: 1.15rem;
  text-decoration: none;
  padding: .85rem 0;
  display: flex;
  align-items: center;
  gap: .4rem;
  white-space: nowrap;
}
.nav-brand span { font-weight: 400; opacity: .7; font-size: .85rem; }
.nav-links {
  display: flex;
  gap: 0;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}
.nav-links a {
  color: rgba(255,255,255,.75);
  text-decoration: none;
  padding: .85rem .75rem;
  font-size: .82rem;
  font-weight: 600;
  white-space: nowrap;
  border-bottom: 3px solid transparent;
  transition: all .2s;
}
.nav-links a:hover,
.nav-links a.active {
  color: #fff;
  border-bottom-color: var(--accent-light);
  background: rgba(255,255,255,.08);
}
.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: #fff;
  font-size: 1.5rem;
  cursor: pointer;
  padding: .5rem;
}
@media (max-width: 767px) {
  .nav-toggle { display: block; }
  .nav-links {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--primary);
    box-shadow: 0 4px 12px rgba(0,0,0,.2);
  }
  .nav-links.open { display: flex; }
  .nav-links a {
    padding: .75rem 1.2rem;
    border-bottom: 1px solid rgba(255,255,255,.1);
    border-left: 3px solid transparent;
  }
  .nav-links a:hover,
  .nav-links a.active { border-left-color: var(--accent-light); border-bottom-color: rgba(255,255,255,.1); }
}

/* ---- Hero ---- */
.hero {
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  color: #fff;
  padding: 3rem 1.5rem;
  text-align: center;
}
.hero h1 {
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  margin-bottom: .5rem;
  font-weight: 800;
}
.hero p { opacity: .85; font-size: 1.1rem; max-width: 640px; margin: 0 auto; }
.hero .sub { margin-top: .5rem; font-size: .9rem; opacity: .65; }

/* ---- Container ---- */
.container { max-width: 1100px; margin: 0 auto; padding: 1.5rem 1rem; }
.container-narrow { max-width: 840px; margin: 0 auto; padding: 1.5rem 1rem; }

/* ---- Cards ---- */
.card {
  background: var(--card);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1rem;
  box-shadow: var(--shadow);
}
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1rem;
}
.feature-card {
  background: var(--card);
  border-radius: var(--radius);
  padding: 1.5rem;
  box-shadow: var(--shadow);
  border-top: 4px solid var(--primary-light);
  transition: transform .2s, box-shadow .2s;
  text-decoration: none;
  color: var(--text);
  display: block;
}
.feature-card:hover { transform: translateY(-3px); box-shadow: 0 6px 20px rgba(0,0,0,.12); }
.feature-card .icon { font-size: 2.2rem; margin-bottom: .6rem; }
.feature-card h3 { font-size: 1.1rem; margin-bottom: .3rem; color: var(--primary); }
.feature-card p { font-size: .88rem; color: var(--text-light); line-height: 1.5; }
.feature-card .arrow { float: right; color: var(--primary-light); font-weight: bold; }

/* ---- Badges ---- */
.badge {
  display: inline-block;
  padding: 3px 12px;
  border-radius: 20px;
  font-size: .75rem;
  font-weight: 700;
  color: #fff;
}
.badge-a2 { background: var(--success); }
.badge-b1 { background: var(--warning); }
.badge-b2 { background: var(--danger); }
.badge-grammar { background: var(--primary); }
.badge-vocab { background: var(--accent); }
.badge-reading { background: #e67e22; }
.badge-listening { background: #16a085; }

/* ---- Buttons ---- */
.btn {
  display: inline-block;
  padding: .7rem 1.8rem;
  border-radius: 10px;
  font-size: .95rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: all .2s;
  text-decoration: none;
  text-align: center;
}
.btn-primary { background: var(--primary-light); color: #fff; }
.btn-primary:hover { background: #1d4ed8; transform: translateY(-1px); }
.btn-accent { background: var(--accent); color: #fff; }
.btn-accent:hover { background: #6d28d9; }
.btn-outline {
  background: transparent;
  color: var(--primary-light);
  border: 2px solid var(--primary-light);
}
.btn-outline:hover { background: var(--primary-bg); }
.btn-success { background: var(--success); color: #fff; }
.btn-success:hover { background: #16a34a; }
.btn:disabled { background: #ccc; cursor: not-allowed; transform: none; }

/* ---- Pill Filters ---- */
.pill-group {
  display: flex;
  flex-wrap: wrap;
  gap: .4rem;
  justify-content: center;
}
.pill {
  padding: .4rem .9rem;
  border: 2px solid var(--primary-light);
  background: #fff;
  color: var(--primary-light);
  border-radius: 20px;
  cursor: pointer;
  font-size: .82rem;
  font-weight: 600;
  transition: .2s;
}
.pill:hover, .pill.active { background: var(--primary-light); color: #fff; }
.pill-accent { border-color: var(--accent); color: var(--accent); }
.pill-accent:hover, .pill-accent.active { background: var(--accent); color: #fff; }

/* ---- Progress Bar ---- */
.progress-bar { background: #e0e0e0; border-radius: 20px; height: 10px; overflow: hidden; }
.progress-fill { height: 100%; border-radius: 20px; transition: width .5s ease; }
.progress-fill.green { background: linear-gradient(90deg, #22c55e, #4ade80); }
.progress-fill.blue { background: linear-gradient(90deg, var(--primary-light), var(--accent-light)); }

/* ---- Score Ring ---- */
.score-ring {
  width: 140px;
  height: 140px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 1rem auto;
  font-size: 2.2rem;
  font-weight: 800;
  color: #fff;
  box-shadow: 0 4px 16px rgba(0,0,0,.15);
}

/* ---- Stat Cards Row ---- */
.stats-row {
  display: flex;
  gap: .8rem;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}
.stat-card {
  background: var(--card);
  border-radius: 10px;
  padding: .7rem 1.2rem;
  text-align: center;
  min-width: 100px;
  box-shadow: var(--shadow);
}
.stat-card .num { font-size: 1.5rem; font-weight: 800; }
.stat-card .label { font-size: .72rem; color: var(--text-light); margin-top: 2px; }

/* ---- Section Accordion ---- */
.accordion { margin-bottom: .8rem; }
.accordion-header {
  background: var(--card);
  padding: .9rem 1.1rem;
  border-radius: var(--radius);
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: .5rem;
  box-shadow: var(--shadow);
  transition: background .2s;
  user-select: none;
}
.accordion-header:hover { background: #f8fafc; }
.accordion-header .arrow { transition: transform .2s; display: inline-block; font-size: .8rem; }
.accordion-header .arrow.open { transform: rotate(90deg); }
.accordion-body {
  display: none;
  padding: 1rem 1.1rem;
  background: var(--card);
  border-radius: 0 0 var(--radius) var(--radius);
  margin-top: -4px;
}
.accordion-body.show { display: block; }

/* ---- Tables ---- */
.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; font-size: .86rem; }
th { background: #eef2ff; padding: .5rem .7rem; text-align: left; font-weight: 600; border-bottom: 2px solid #c7d2fe; }
td { padding: .45rem .7rem; border-bottom: 1px solid #f1f5f9; }
tr:hover td { background: #fafbff; }

/* ---- Tip/Example/Warning boxes ---- */
.tip-box { background: #fef3c7; border-left: 4px solid var(--warning); padding: .7rem 1rem; border-radius: 0 8px 8px 0; margin: .6rem 0; font-size: .88rem; }
.example-box { background: #f0fdf4; border-left: 4px solid var(--success); padding: .7rem 1rem; border-radius: 0 8px 8px 0; margin: .6rem 0; font-size: .88rem; }
.info-box { background: #eff6ff; border-left: 4px solid var(--primary-light); padding: .7rem 1rem; border-radius: 0 8px 8px 0; margin: .6rem 0; font-size: .88rem; }

/* ---- Footer ---- */
.footer {
  background: var(--primary);
  color: rgba(255,255,255,.7);
  text-align: center;
  padding: 1.5rem 1rem;
  margin-top: 3rem;
  font-size: .85rem;
}
.footer a { color: var(--accent-light); text-decoration: none; }
.footer a:hover { text-decoration: underline; }

/* ---- Conversation Bubble ---- */
.conversation { max-width: 600px; margin: 1rem auto; }
.bubble {
  padding: .7rem 1rem;
  border-radius: 14px;
  margin-bottom: .5rem;
  max-width: 85%;
  font-size: .92rem;
  line-height: 1.5;
  position: relative;
}
.bubble-left {
  background: #eef2ff;
  color: var(--text);
  border-bottom-left-radius: 4px;
  margin-right: auto;
}
.bubble-right {
  background: #fefce8;
  color: var(--text);
  border-bottom-right-radius: 4px;
  margin-left: auto;
}
.bubble-label {
  font-size: .7rem;
  font-weight: 700;
  text-transform: uppercase;
  margin-bottom: 2px;
  color: var(--primary);
}

/* ---- Quiz Specific ---- */
.quiz-options { display: flex; flex-direction: column; gap: .5rem; }
.quiz-opt {
  padding: .85rem 1.1rem;
  border: 2px solid var(--border);
  border-radius: 10px;
  cursor: pointer;
  transition: all .2s;
  font-size: .95rem;
}
.quiz-opt:hover { border-color: var(--primary-light); background: #f0f7ff; }
.quiz-opt.selected { border-color: var(--primary-light); background: var(--primary-bg); font-weight: 500; }
.quiz-opt.correct { border-color: var(--success); background: #e8f8e8; }
.quiz-opt.wrong { border-color: var(--danger); background: #fde8e8; }

/* ---- Utility ---- */
.text-center { text-align: center; }
.mt-1 { margin-top: .5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mb-1 { margin-bottom: .5rem; }
.mb-2 { margin-bottom: 1rem; }
.flex-center { display: flex; justify-content: center; align-items: center; gap: .5rem; }
.gap-1 { gap: .5rem; }
.gap-2 { gap: 1rem; }
.hidden { display: none !important; }

/* ---- Streak / Gamification ---- */
.streak-bar {
  background: var(--card);
  border-radius: var(--radius);
  padding: 1rem 1.2rem;
  display: flex;
  align-items: center;
  gap: 1rem;
  box-shadow: var(--shadow);
  margin-bottom: 1.5rem;
}
.streak-bar .flame { font-size: 2rem; }
.streak-bar .info { flex: 1; }
.streak-bar .days { font-size: 1.3rem; font-weight: 800; color: var(--warning); }
.streak-bar .label { font-size: .8rem; color: var(--text-light); }

.text-muted { color: var(--text-light); font-size: 0.9rem; }

@media print {
  .nav, .footer, .btn, .nav-toggle { display: none; }
  body { background: #fff; }
  .card { box-shadow: none; border: 1px solid #ddd; }
}