/* =====================================================
   THẦY STEVEN NGUYEN – GIA SƯ TOÁN | LANDING PAGE
   style.css – Project 1
   ===================================================== */

/* ── 1. RESET & ROOT VARIABLES ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --mint:       #34d399;
  --mint-dark:  #059669;
  --blue:       #60a5fa;
  --blue-dark:  #2563eb;
  --amber:      #f59e0b;
  --amber-dark: #d97706;
  --white:      #ffffff;
  --gray-50:    #f9fafb;
  --gray-100:   #f3f4f6;
  --gray-200:   #e5e7eb;
  --gray-400:   #9ca3af;
  --gray-600:   #4b5563;
  --gray-700:   #374151;
  --gray-900:   #111827;
  --shadow-sm:  0 1px 3px rgba(0,0,0,.08);
  --shadow-md:  0 4px 16px rgba(0,0,0,.10);
  --shadow-lg:  0 12px 40px rgba(0,0,0,.14);
  --radius:     14px;
  --radius-lg:  22px;
  --transition: .25s ease;
}

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', sans-serif;
  font-size: 16px;
  color: var(--gray-700);
  background: var(--white);
  overflow-x: hidden;
}

h1,h2,h3,h4,h5 { font-family: 'Montserrat', sans-serif; color: var(--gray-900); line-height: 1.25; }
a { text-decoration: none; color: inherit; transition: color var(--transition); }
img { max-width: 100%; height: auto; display: block; }
ul { list-style: none; }

.container { max-width: 1160px; margin: 0 auto; padding: 0 20px; }
.section-pad { padding: 90px 0; }
.bg-light { background: var(--gray-50); }

/* ── 2. TYPOGRAPHY HELPERS ── */
.section-label {
  display: inline-block;
  font-size: .78rem;
  font-weight: 600;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--mint-dark);
  background: rgba(52,211,153,.12);
  padding: 5px 14px;
  border-radius: 50px;
  margin-bottom: 14px;
}

.section-title {
  font-size: clamp(1.75rem, 3.5vw, 2.4rem);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 16px;
}

.section-desc {
  font-size: 1.05rem;
  color: var(--gray-600);
  max-width: 600px;
  line-height: 1.7;
}

.section-header { text-align: center; margin-bottom: 54px; }
.section-header .section-desc { margin: 0 auto; }

.highlight { color: var(--mint-dark); }
.accent-text { color: var(--amber); }

/* ── 3. BUTTONS ── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 26px;
  border-radius: 50px;
  font-family: 'Montserrat', sans-serif;
  font-weight: 600;
  font-size: .95rem;
  cursor: pointer;
  border: 2px solid transparent;
  transition: all var(--transition);
  white-space: nowrap;
}

.btn-primary {
  background: linear-gradient(135deg, var(--mint), var(--mint-dark));
  color: var(--white);
  box-shadow: 0 4px 20px rgba(52,211,153,.35);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 8px 28px rgba(52,211,153,.45); }

.btn-outline {
  background: transparent;
  color: var(--gray-900);
  border-color: var(--gray-200);
}
.btn-outline:hover { border-color: var(--mint); color: var(--mint-dark); background: rgba(52,211,153,.06); }

.btn-lg { padding: 15px 32px; font-size: 1rem; }
.btn-full { width: 100%; justify-content: center; }
.btn-nav {
  background: linear-gradient(135deg, var(--mint), var(--mint-dark));
  color: var(--white) !important;
  padding: 10px 22px;
  border-radius: 50px;
  font-size: .88rem;
}
.btn-nav:hover { opacity: .9; transform: translateY(-1px); }

/* ── 4. NAVIGATION ── */
.navbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  background: rgba(255,255,255,.85);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid transparent;
  transition: all var(--transition);
}
.navbar.scrolled { border-bottom-color: var(--gray-200); box-shadow: var(--shadow-sm); }

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: 'Montserrat', sans-serif;
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--gray-900);
}
.logo-icon {
  width: 38px; height: 38px;
  background: linear-gradient(135deg, var(--mint), var(--mint-dark));
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  color: var(--white);
  font-size: 1rem;
}

.nav-links { display: flex; align-items: center; gap: 10px; }
.nav-links a {
  font-size: .9rem;
  font-weight: 500;
  color: var(--gray-600);
  padding: 6px 12px;
  border-radius: 8px;
}
.nav-links a:not(.btn-nav):hover { color: var(--mint-dark); background: rgba(52,211,153,.08); }

.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px;
}
.hamburger span {
  display: block;
  width: 24px; height: 2px;
  background: var(--gray-700);
  border-radius: 2px;
  transition: all var(--transition);
}

/* ── 5. HERO SECTION ── */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: 100px 0 60px;
  background: linear-gradient(135deg, #ecfdf5 0%, #eff6ff 50%, #fefce8 100%);
  overflow: hidden;
}

.hero-bg-shapes { position: absolute; inset: 0; pointer-events: none; }
.shape {
  position: absolute;
  border-radius: 50%;
  opacity: .18;
}
.shape-1 {
  width: 500px; height: 500px;
  background: radial-gradient(circle, var(--mint), transparent);
  top: -120px; right: -100px;
}
.shape-2 {
  width: 300px; height: 300px;
  background: radial-gradient(circle, var(--blue), transparent);
  bottom: 50px; left: -80px;
}
.shape-3 {
  width: 200px; height: 200px;
  background: radial-gradient(circle, var(--amber), transparent);
  top: 40%; left: 40%;
}

.hero-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: center;
  position: relative;
  z-index: 1;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(245,158,11,.12);
  color: var(--amber-dark);
  font-size: .8rem;
  font-weight: 600;
  padding: 6px 14px;
  border-radius: 50px;
  margin-bottom: 20px;
  border: 1px solid rgba(245,158,11,.2);
}

.hero-title {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 20px;
}

.hero-sub {
  font-size: 1.08rem;
  color: var(--gray-600);
  line-height: 1.75;
  margin-bottom: 24px;
}

.hero-benefits { margin-bottom: 32px; }
.hero-benefits li {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: .98rem;
  color: var(--gray-700);
  margin-bottom: 10px;
}
.hero-benefits li i { color: var(--mint-dark); font-size: 1.05rem; flex-shrink: 0; }

.hero-cta { display: flex; flex-wrap: wrap; gap: 14px; margin-bottom: 20px; }

.zalo-float-hero {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: #0068ff;
  font-size: .9rem;
  font-weight: 600;
  padding: 8px 16px;
  background: rgba(0,104,255,.08);
  border-radius: 50px;
  border: 1px solid rgba(0,104,255,.2);
  transition: all var(--transition);
}
.zalo-float-hero:hover { background: rgba(0,104,255,.14); transform: translateY(-2px); }

/* Hero photo */
.hero-photo { display: flex; justify-content: center; }
.photo-wrapper { position: relative; width: 420px; max-width: 100%; }

.avatar-hero {
  width: 380px;
  height: 380px;
  border-radius: 50%;
  object-fit: cover;
  border: 6px solid var(--white);
  box-shadow: 0 20px 60px rgba(52,211,153,.25), 0 4px 24px rgba(0,0,0,.12);
  margin: 0 auto;
}

.photo-badge {
  position: absolute;
  background: var(--white);
  border-radius: var(--radius);
  padding: 10px 16px;
  box-shadow: var(--shadow-md);
  display: flex;
  flex-direction: column;
  align-items: center;
  font-family: 'Montserrat', sans-serif;
}
.photo-badge strong { font-size: 1.3rem; font-weight: 800; color: var(--gray-900); line-height: 1; }
.photo-badge span { font-size: .72rem; color: var(--gray-400); font-weight: 500; }

.badge-exp { top: 10px; left: 0; min-width: 78px; }
.badge-exp strong { color: var(--mint-dark); }
.badge-students { bottom: 60px; left: -20px; min-width: 92px; }
.badge-students strong { color: var(--blue-dark); }
.badge-rate { bottom: 10px; right: -10px; min-width: 90px; }
.badge-rate strong { color: var(--amber-dark); }

.scroll-hint {
  position: absolute;
  bottom: 28px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  font-size: .78rem;
  color: var(--gray-400);
  letter-spacing: .06em;
  animation: bounce 2s infinite;
}
@keyframes bounce { 0%,100%{transform:translateX(-50%) translateY(0)} 50%{transform:translateX(-50%) translateY(6px)} }

/* ── 6. STATS BAR ── */
.stats-bar {
  background: linear-gradient(135deg, var(--mint-dark), #0d9488);
  padding: 32px 0;
}
.stats-inner {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  text-align: center;
}
.stat-item { color: var(--white); }
.stat-num {
  font-family: 'Montserrat', sans-serif;
  font-size: 2.2rem;
  font-weight: 800;
  line-height: 1;
}
.stat-item p { font-size: .85rem; opacity: .85; margin-top: 6px; }

/* ── 7. ABOUT ── */
.about-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 70px;
  align-items: center;
}

.about-img { position: relative; }
.about-photo {
  width: 100%;
  border-radius: var(--radius-lg);
  object-fit: cover;
  height: 520px;
  box-shadow: var(--shadow-lg);
}
.about-img-badge {
  position: absolute;
  bottom: -16px; left: 20px;
  background: linear-gradient(135deg, var(--mint), var(--mint-dark));
  color: var(--white);
  font-size: .82rem;
  font-weight: 600;
  padding: 10px 18px;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  gap: 8px;
  box-shadow: var(--shadow-md);
}

.about-content p {
  font-size: 1rem;
  line-height: 1.8;
  color: var(--gray-600);
  margin-bottom: 18px;
}

.about-highlights {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin: 28px 0;
}
.highlight-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px;
  background: var(--gray-50);
  border-radius: var(--radius);
  border: 1px solid var(--gray-200);
}
.hl-icon {
  width: 42px; height: 42px;
  background: linear-gradient(135deg, var(--mint), var(--mint-dark));
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  color: var(--white);
  font-size: 1.1rem;
  flex-shrink: 0;
}
.hl-info { display: flex; flex-direction: column; }
.hl-info strong { font-size: .88rem; color: var(--gray-900); font-weight: 700; }
.hl-info span { font-size: .75rem; color: var(--gray-400); }

/* ── 8. RESULTS SECTION ── */
.results { background: var(--white); }
.results-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-bottom: 48px;
}

.result-card {
  background: var(--white);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-md);
  border: 1px solid var(--gray-100);
  transition: transform var(--transition), box-shadow var(--transition);
}
.result-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-lg); }

.result-img { position: relative; overflow: hidden; }
.result-img img { width: 100%; height: 180px; object-fit: cover; transition: transform .4s ease; }
.result-card:hover .result-img img { transform: scale(1.05); }
.result-subject-tag {
  position: absolute;
  top: 12px; left: 12px;
  background: linear-gradient(135deg, var(--mint), var(--mint-dark));
  color: var(--white);
  font-size: .72rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 50px;
}

.result-body { padding: 20px; }
.score-change {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
}
.score-before, .score-after {
  font-family: 'Montserrat', sans-serif;
  font-size: 1.5rem;
  font-weight: 800;
  border-radius: 8px;
  padding: 4px 10px;
}
.score-before { background: rgba(239,68,68,.1); color: #dc2626; }
.score-after  { background: rgba(52,211,153,.15); color: var(--mint-dark); }
.score-change i { color: var(--amber); font-size: 1rem; }

.result-body h4 { font-size: .95rem; margin-bottom: 8px; color: var(--gray-900); }
.result-body p { font-size: .88rem; color: var(--gray-600); line-height: 1.65; font-style: italic; margin-bottom: 10px; }
.result-meta { font-size: .78rem; color: var(--gray-400); display: flex; align-items: center; gap: 6px; }

.results-cta { text-align: center; }
.results-cta p { font-size: 1.1rem; color: var(--gray-600); margin-bottom: 20px; font-weight: 500; }

/* ── 9. SUBJECTS GRID ── */
.subjects-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 22px;
}

.subject-card {
  background: var(--white);
  border-radius: var(--radius-lg);
  padding: 28px 22px;
  text-align: center;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--gray-100);
  transition: all var(--transition);
}
.subject-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-lg); border-color: var(--mint); }

.subject-icon {
  width: 58px; height: 58px;
  border-radius: 16px;
  display: flex; align-items: center; justify-content: center;
  margin: 0 auto 18px;
  color: var(--white);
  font-size: 1.5rem;
  box-shadow: 0 6px 20px rgba(0,0,0,.12);
}
.subject-card h4 { font-size: 1rem; margin-bottom: 10px; }
.subject-card p { font-size: .83rem; color: var(--gray-600); line-height: 1.6; margin-bottom: 14px; }

.subject-tag {
  display: inline-block;
  font-size: .72rem;
  font-weight: 600;
  padding: 4px 12px;
  border-radius: 50px;
  background: rgba(52,211,153,.12);
  color: var(--mint-dark);
}
.subject-tag-blue { background: rgba(96,165,250,.15); color: var(--blue-dark); }
.subject-tag-yellow { background: rgba(245,158,11,.12); color: var(--amber-dark); }
.subject-tag-purple { background: rgba(167,139,250,.15); color: #7c3aed; }
.subject-tag-pink { background: rgba(244,114,182,.15); color: #db2777; }
.subject-tag-orange { background: rgba(251,146,60,.15); color: #ea580c; }

/* ── 10. METHOD SECTION ── */
.method {
  position: relative;
  background: linear-gradient(135deg, #0f172a 0%, #1e3a5f 100%);
  overflow: hidden;
}
.method-bg {
  position: absolute; inset: 0;
  background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%2334d399' fill-opacity='0.04'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
}
.method .section-label { background: rgba(52,211,153,.17); color: var(--mint); }
.method .section-title { color: var(--white); }
.method .section-desc { color: rgba(255,255,255,.65); }

.method-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 20px;
  position: relative;
  z-index: 1;
}

.method-card {
  background: rgba(255,255,255,.06);
  border: 1px solid rgba(255,255,255,.1);
  border-radius: var(--radius-lg);
  padding: 30px 22px;
  transition: all var(--transition);
  backdrop-filter: blur(6px);
}
.method-card:hover { background: rgba(52,211,153,.12); border-color: var(--mint); transform: translateY(-4px); }

.method-num {
  font-family: 'Montserrat', sans-serif;
  font-size: 2.4rem;
  font-weight: 800;
  color: rgba(52,211,153,.2);
  line-height: 1;
  margin-bottom: 14px;
}
.method-icon {
  width: 50px; height: 50px;
  background: linear-gradient(135deg, var(--mint), var(--mint-dark));
  border-radius: 14px;
  display: flex; align-items: center; justify-content: center;
  color: var(--white);
  font-size: 1.2rem;
  margin-bottom: 16px;
}
.method-card h4 { font-size: .95rem; color: var(--white); margin-bottom: 10px; line-height: 1.35; }
.method-card p { font-size: .83rem; color: rgba(255,255,255,.6); line-height: 1.7; }

/* ── 11. TESTIMONIALS ── */
.testimonial-carousel { position: relative; overflow: hidden; }
.testimonial-track {
  display: flex;
  gap: 24px;
  transition: transform .45s cubic-bezier(.4,.0,.2,1);
}

.testimonial-card {
  background: var(--white);
  border-radius: var(--radius-lg);
  padding: 30px;
  box-shadow: var(--shadow-md);
  border: 1px solid var(--gray-100);
  width: calc(33.333% - 16px);
  flex-shrink: 0;
  min-width: 0;
}

.testi-stars { color: var(--amber); font-size: 1.1rem; margin-bottom: 14px; letter-spacing: 2px; }
.testi-quote {
  font-size: .93rem;
  color: var(--gray-600);
  line-height: 1.75;
  font-style: italic;
  margin-bottom: 20px;
  position: relative;
}
.testi-quote::before {
  content: '"';
  font-size: 4rem;
  color: var(--mint);
  opacity: .18;
  position: absolute;
  top: -14px; left: -8px;
  font-family: 'Montserrat', sans-serif;
  line-height: 1;
}

.testi-author {
  display: flex;
  align-items: center;
  gap: 14px;
}
.testi-author img {
  width: 50px; height: 50px;
  border-radius: 50%;
  object-fit: cover;
  border: 2px solid var(--mint);
}
.testi-author strong { display: block; font-size: .9rem; color: var(--gray-900); }
.testi-author span { font-size: .78rem; color: var(--gray-400); }

.carousel-controls {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  margin-top: 32px;
}
.carousel-btn {
  width: 44px; height: 44px;
  border-radius: 50%;
  border: 2px solid var(--gray-200);
  background: var(--white);
  color: var(--gray-600);
  cursor: pointer;
  font-size: 1rem;
  display: flex; align-items: center; justify-content: center;
  transition: all var(--transition);
}
.carousel-btn:hover { border-color: var(--mint); color: var(--mint-dark); }

.carousel-dots { display: flex; gap: 8px; }
.dot {
  width: 8px; height: 8px;
  border-radius: 50%;
  background: var(--gray-200);
  cursor: pointer;
  transition: all var(--transition);
}
.dot.active { background: var(--mint-dark); width: 24px; border-radius: 4px; }

/* ── 12. PRICING ── */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
  margin-bottom: 36px;
}

.pricing-card {
  background: var(--white);
  border-radius: var(--radius-lg);
  padding: 36px 28px;
  box-shadow: var(--shadow-md);
  border: 2px solid var(--gray-100);
  transition: all var(--transition);
  position: relative;
}
.pricing-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-lg); }

.pricing-featured {
  border-color: var(--mint);
  background: linear-gradient(to bottom, rgba(52,211,153,.04), var(--white));
}
.pricing-badge {
  position: absolute;
  top: -14px; left: 50%;
  transform: translateX(-50%);
  background: linear-gradient(135deg, var(--amber), var(--amber-dark));
  color: var(--white);
  font-size: .75rem;
  font-weight: 700;
  padding: 5px 16px;
  border-radius: 50px;
  white-space: nowrap;
  letter-spacing: .06em;
  box-shadow: 0 4px 14px rgba(245,158,11,.3);
}

.pricing-header { text-align: center; margin-bottom: 24px; }
.pricing-icon {
  width: 60px; height: 60px;
  background: linear-gradient(135deg, var(--mint), var(--mint-dark));
  border-radius: 18px;
  display: flex; align-items: center; justify-content: center;
  color: var(--white);
  font-size: 1.4rem;
  margin: 0 auto 14px;
}
.pricing-header h3 { font-size: 1.25rem; margin-bottom: 6px; }
.pricing-header p { font-size: .83rem; color: var(--gray-400); }

.pricing-price { text-align: center; margin-bottom: 24px; padding: 16px 0; border-top: 1px solid var(--gray-100); border-bottom: 1px solid var(--gray-100); }
.price-amount { font-family: 'Montserrat', sans-serif; font-size: 2rem; font-weight: 800; color: var(--mint-dark); }
.price-per { font-size: .83rem; color: var(--gray-400); display: block; margin-top: 4px; }

.pricing-features { margin-bottom: 28px; }
.pricing-features li {
  display: flex; align-items: center; gap: 10px;
  font-size: .88rem;
  color: var(--gray-600);
  padding: 8px 0;
  border-bottom: 1px solid var(--gray-100);
}
.pricing-features li:last-child { border-bottom: none; }
.pricing-features li i { color: var(--mint-dark); flex-shrink: 0; }

.pricing-note {
  background: linear-gradient(135deg, rgba(52,211,153,.1), rgba(96,165,250,.1));
  border: 1px solid rgba(52,211,153,.25);
  border-radius: var(--radius);
  padding: 20px 28px;
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: .95rem;
  color: var(--gray-700);
  margin-bottom: 36px;
}
.pricing-note i { color: var(--amber-dark); font-size: 1.3rem; flex-shrink: 0; }
.pricing-note a { color: var(--mint-dark); font-weight: 600; margin-left: 6px; }

.schedule-table {
  background: var(--gray-50);
  border-radius: var(--radius-lg);
  padding: 32px;
  border: 1px solid var(--gray-100);
}
.schedule-table h3 { font-size: 1.15rem; margin-bottom: 20px; display: flex; align-items: center; gap: 10px; }
.schedule-table h3 i { color: var(--mint-dark); }
.schedule-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}
.schedule-item {
  background: var(--white);
  border-radius: var(--radius);
  padding: 16px;
  text-align: center;
  border: 1px solid var(--gray-100);
}
.schedule-item strong { display: block; font-size: .88rem; color: var(--gray-900); margin-bottom: 6px; }
.schedule-item span { font-size: .82rem; color: var(--mint-dark); font-weight: 600; }

/* ── 13. HOW IT WORKS ── */
.howto-steps {
  display: flex;
  align-items: flex-start;
  gap: 0;
  position: relative;
}

.step-card {
  flex: 1;
  text-align: center;
  padding: 32px 20px;
  background: var(--white);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--gray-100);
  transition: all var(--transition);
}
.step-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); border-color: var(--mint); }

.step-connector {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0 8px;
  color: var(--mint);
  font-size: 1.2rem;
  margin-top: 60px;
  flex-shrink: 0;
}

.step-num {
  font-family: 'Montserrat', sans-serif;
  font-size: 2.8rem;
  font-weight: 800;
  color: rgba(52,211,153,.15);
  line-height: 1;
  margin-bottom: 12px;
}
.step-icon {
  width: 56px; height: 56px;
  background: linear-gradient(135deg, var(--mint), var(--mint-dark));
  border-radius: 16px;
  display: flex; align-items: center; justify-content: center;
  color: var(--white);
  font-size: 1.3rem;
  margin: 0 auto 16px;
}
.step-card h4 { font-size: 1rem; margin-bottom: 10px; }
.step-card p { font-size: .85rem; color: var(--gray-600); line-height: 1.7; }

/* ── 14. CONTACT ── */
.contact { background: linear-gradient(135deg, #ecfdf5, #eff6ff); }
.contact-inner {
  display: grid;
  grid-template-columns: 1fr 1.1fr;
  gap: 60px;
  align-items: start;
}

.contact-info p { font-size: 1rem; color: var(--gray-600); line-height: 1.75; margin-bottom: 32px; }

.contact-methods { display: flex; flex-direction: column; gap: 14px; margin-bottom: 32px; }
.contact-method {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 16px 20px;
  background: var(--white);
  border-radius: var(--radius);
  border: 1px solid var(--gray-100);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition);
}
.contact-method:hover { border-color: var(--mint); transform: translateX(4px); box-shadow: var(--shadow-md); }

.cm-icon {
  width: 44px; height: 44px;
  background: linear-gradient(135deg, var(--mint), var(--mint-dark));
  border-radius: 12px;
  display: flex; align-items: center; justify-content: center;
  color: var(--white);
  font-size: 1.1rem;
  flex-shrink: 0;
}
.cm-zalo { background: linear-gradient(135deg, #0068ff, #004dd1); }
.cm-fb { background: linear-gradient(135deg, #1877f2, #0d5bbf); }
.contact-method strong { display: block; font-size: .9rem; color: var(--gray-900); }
.contact-method span { font-size: .82rem; color: var(--gray-400); }

.contact-img {
  width: 100%;
  border-radius: var(--radius-lg);
  object-fit: cover;
  height: 200px;
  box-shadow: var(--shadow-md);
}

/* Contact Form */
.contact-form {
  background: var(--white);
  border-radius: var(--radius-lg);
  padding: 40px;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--gray-100);
}
.contact-form h3 {
  font-size: 1.2rem;
  margin-bottom: 28px;
  display: flex; align-items: center; gap: 10px;
  color: var(--gray-900);
}
.contact-form h3 i { color: var(--mint-dark); }

.form-group { margin-bottom: 20px; }
.form-group label {
  display: block;
  font-size: .88rem;
  font-weight: 600;
  color: var(--gray-700);
  margin-bottom: 8px;
}
.req { color: #ef4444; }

.form-group input,
.form-group select,
.form-group textarea {
  width: 100%;
  padding: 12px 16px;
  border: 1.5px solid var(--gray-200);
  border-radius: 10px;
  font-family: 'Inter', sans-serif;
  font-size: .93rem;
  color: var(--gray-700);
  background: var(--white);
  transition: border-color var(--transition), box-shadow var(--transition);
  outline: none;
  resize: vertical;
}
.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  border-color: var(--mint);
  box-shadow: 0 0 0 3px rgba(52,211,153,.15);
}
.form-group input.error,
.form-group select.error { border-color: #ef4444; }
.form-error { font-size: .78rem; color: #ef4444; margin-top: 5px; display: block; }

.form-disclaimer {
  font-size: .78rem;
  color: var(--gray-400);
  text-align: center;
  margin-top: 14px;
  display: flex; align-items: center; justify-content: center; gap: 6px;
}

.form-success {
  text-align: center;
  padding: 32px 16px;
}
.success-icon { font-size: 3.5rem; color: var(--mint-dark); margin-bottom: 16px; }
.form-success h3 { margin-bottom: 12px; }
.form-success p { color: var(--gray-600); margin-bottom: 24px; line-height: 1.7; }

/* ── 15. FOOTER ── */
.footer {
  background: #0f172a;
  color: rgba(255,255,255,.7);
  padding: 64px 0 0;
}
.footer-inner {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 50px;
  padding-bottom: 48px;
  border-bottom: 1px solid rgba(255,255,255,.08);
}
.logo-white { color: var(--white); }
.footer-brand p {
  font-size: .88rem;
  line-height: 1.75;
  margin: 16px 0 24px;
  color: rgba(255,255,255,.55);
}
.footer-social { display: flex; gap: 12px; }
.footer-social a {
  width: 40px; height: 40px;
  background: rgba(255,255,255,.08);
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  color: rgba(255,255,255,.6);
  font-size: .95rem;
  transition: all var(--transition);
}
.footer-social a:hover { background: var(--mint-dark); color: var(--white); }

.footer-links h4,
.footer-contact h4 {
  font-size: .9rem;
  color: var(--white);
  margin-bottom: 18px;
  letter-spacing: .06em;
  text-transform: uppercase;
}
.footer-links a {
  display: block;
  font-size: .85rem;
  color: rgba(255,255,255,.55);
  padding: 5px 0;
  transition: color var(--transition);
}
.footer-links a:hover { color: var(--mint); }

.footer-contact p {
  font-size: .85rem;
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 6px 0;
  color: rgba(255,255,255,.55);
}
.footer-contact p i { color: var(--mint); width: 16px; }
.footer-contact p a { color: rgba(255,255,255,.55); }
.footer-contact p a:hover { color: var(--mint); }

.footer-bottom {
  text-align: center;
  padding: 20px;
  font-size: .8rem;
  color: rgba(255,255,255,.3);
}

/* ── 16. FLOATING BUTTONS ── */
.float-buttons {
  position: fixed;
  right: 20px; bottom: 24px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  z-index: 900;
}
.float-btn {
  position: relative;
  width: 54px; height: 54px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  cursor: pointer;
  box-shadow: 0 4px 20px rgba(0,0,0,.18);
  border: none;
  transition: all var(--transition);
  overflow: visible;
}
.float-btn:hover { transform: scale(1.1); }
.float-btn:hover .float-label { opacity: 1; transform: translateX(0); pointer-events: auto; }

.float-label {
  position: absolute;
  right: 62px;
  background: var(--gray-900);
  color: var(--white);
  font-size: .75rem;
  font-weight: 600;
  padding: 5px 12px;
  border-radius: 6px;
  white-space: nowrap;
  opacity: 0;
  transform: translateX(8px);
  transition: all var(--transition);
  pointer-events: none;
}
.float-label::after {
  content: '';
  position: absolute;
  right: -5px; top: 50%;
  transform: translateY(-50%);
  border: 5px solid transparent;
  border-left-color: var(--gray-900);
}

.float-zalo { background: #0068ff; }
.float-phone { background: linear-gradient(135deg, var(--mint), var(--mint-dark)); color: var(--white); font-size: 1.2rem; }
.float-top { background: var(--white); color: var(--gray-600); border: 2px solid var(--gray-200); font-size: 1rem; }
.float-top:hover { border-color: var(--mint); color: var(--mint-dark); }

/* ── 17. MOBILE RESPONSIVE ── */
@media (max-width: 1024px) {
  .method-grid { grid-template-columns: repeat(3, 1fr); }
  .subjects-grid { grid-template-columns: repeat(3, 1fr); }
  .results-grid { grid-template-columns: repeat(2, 1fr); }
  .stats-inner { grid-template-columns: repeat(2, 1fr); }
  .testimonial-card { width: calc(50% - 12px); }
}

@media (max-width: 768px) {
  .section-pad { padding: 60px 0; }

  /* Nav */
  .hamburger { display: flex; }
  .nav-links {
    display: none;
    position: absolute;
    top: 68px; left: 0; right: 0;
    background: var(--white);
    z-index: 999;
    flex-direction: column;
    padding: 20px;
    gap: 6px;
    box-shadow: 0 10px 30px rgba(0,0,0,.1);
    border-top: 1px solid var(--gray-100);
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 10px 12px; width: 100%; }

  /* Hero */
  .hero-inner { grid-template-columns: 1fr; gap: 40px; text-align: center; }
  .hero-photo { order: -1; }
  .avatar-hero { width: 260px; height: 260px; }
  .photo-wrapper { width: 300px; margin: 0 auto; }
  .hero-cta { justify-content: center; flex-direction: column; }
  .zalo-float-hero { justify-content: center; }
  .hero-benefits { text-align: left; }
  .badge-exp { left: 0; }
  .badge-students { left: 0; bottom: 0; }
  .badge-rate { right: 0; bottom: 0; }

  /* About */
  .about-inner { grid-template-columns: 1fr; gap: 40px; }
  .about-photo { height: 300px; }
  .about-highlights { grid-template-columns: 1fr; }

  /* Results */
  .results-grid { grid-template-columns: 1fr; }

  /* Subjects */
  .subjects-grid { grid-template-columns: repeat(2, 1fr); }

  /* Method */
  .method-grid { grid-template-columns: 1fr 1fr; }

  /* Testimonials */
  .testimonial-card { width: calc(100% - 24px); }

  /* Pricing */
  .pricing-grid { grid-template-columns: 1fr; }

  /* Steps */
  .howto-steps { flex-direction: column; gap: 16px; align-items: stretch; }
  .step-connector { display: none; }

  /* Contact */
  .contact-inner { grid-template-columns: 1fr; gap: 40px; }
  .contact-form { padding: 28px 20px; }

  /* Footer */
  .footer-inner { grid-template-columns: 1fr; gap: 36px; }

  /* Schedule */
  .schedule-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 480px) {
  .subjects-grid { grid-template-columns: 1fr 1fr; }
  .method-grid { grid-template-columns: 1fr; }
  .stats-inner { grid-template-columns: repeat(2, 1fr); }
  .btn-lg { padding: 13px 22px; font-size: .92rem; }
  .pricing-note { flex-direction: column; text-align: center; }
  .schedule-grid { grid-template-columns: 1fr 1fr; }
}