:root {
  --bg: #fafaf9;
  --surface: #ffffff;
  --ink: #0a0a0a;
  --gold: #d97706;
  --gold-light: #fef3c7;
  --gold-dark: #92400e;
  --muted: #6b7280;
  --muted-light: #9ca3af;
  --border: #e5e7eb;
  --purple: #8b5cf6;
  --purple-light: #ede9fe;
  --blue: #3b82f6;
  --blue-light: #dbeafe;
  --green: #10b981;
  --green-light: #d1fae5;
  --card-shadow: 0 1px 3px rgba(0, 0, 0, 0.05), 0 10px 40px rgba(0, 0, 0, 0.03);
  --card-shadow-hover: 0 4px 6px rgba(0, 0, 0, 0.05), 0 20px 60px rgba(0, 0, 0, 0.06);
  --radius: 16px;
  --max-w: 1280px;
  --section-padding: 120px;
  --section-gap: 80px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: Inter, system-ui, -apple-system, "Segoe UI", Roboto, Arial;
  color: var(--ink);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  line-height: 1.6;
  font-size: 16px;
}

a {
  color: inherit;
  text-decoration: none;
  transition: all 0.2s ease;
}

img {
  display: block;
  max-width: 100%;
  height: auto;
}

ul {
  list-style: none;
}

button {
  font-family: inherit;
  cursor: pointer;
}

.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 40px;
}

/* ===== HEADER ===== */
header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.98);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.02);
}

.nav {
  height: 80px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: flex;
  align-items: center;
}

.logo {
  display: flex;
  align-items: center;
}

.logo-image {
  height: 40px;
  width: auto;
  display: block;
}

.nav-links {
  display: flex;
  gap: 8px;
  align-items: center;
}

.nav-links a {
  font-weight: 500;
  font-size: 15px;
  padding: 10px 16px;
  border-radius: 8px;
  transition: all 0.2s ease;
}

.nav-links a:hover {
  background: var(--gold-light);
  color: var(--gold-dark);
}

.math-dropdown {
  position: relative;
}

.dropdown-panel {
  position: absolute;
  top: calc(100% + 8px);
  left: 0;
  background: var(--surface);
  padding: 8px;
  border-radius: 12px;
  box-shadow: var(--card-shadow);
  display: none;
  min-width: 180px;
  border: 1px solid var(--border);
}

.math-dropdown:hover .dropdown-panel,
.math-dropdown:focus-within .dropdown-panel {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.dropdown-panel a {
  padding: 12px 16px;
  border-radius: 8px;
  font-weight: 500;
  font-size: 14px;
  transition: all 0.2s ease;
}

.dropdown-panel a:hover {
  background: var(--gold-light);
  color: var(--gold-dark);
}

/* ===== BUTTONS ===== */
.btn {
  font-family: Poppins, sans-serif;
  font-weight: 600;
  font-size: 15px;
  border: none;
  border-radius: 10px;
  padding: 14px 28px;
  cursor: pointer;
  transition: all 0.3s ease;
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.btn-primary {
  background: var(--gold);
  color: white;
  box-shadow: 0 4px 14px rgba(217, 119, 6, 0.25);
}

.btn-primary:hover {
  background: var(--gold-dark);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(217, 119, 6, 0.35);
}

.btn-ghost {
  background: transparent;
  border: 2px solid var(--border);
  color: var(--ink);
}

.btn-ghost:hover {
  border-color: var(--gold);
  background: var(--gold-light);
  color: var(--gold-dark);
}

/* ===== MAIN LAYOUT ===== */
main {
  min-height: 100vh;
}

/* ===== HERO SECTION ===== */
.hero {
  min-height: 100vh;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 80px;
  align-items: center;
  padding: 100px 0;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--gold-light);
  padding: 8px 16px;
  border-radius: 999px;
  font-weight: 600;
  color: var(--gold-dark);
  font-size: 14px;
  margin-bottom: 24px;
}

h1 {
  font-family: Poppins, sans-serif;
  font-size: 64px;
  font-weight: 700;
  line-height: 1.1;
  margin: 0 0 24px 0;
  letter-spacing: -1.5px;
}

h1 .accent {
  color: var(--gold);
  background: linear-gradient(135deg, var(--gold) 0%, var(--gold-dark) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.lead {
  color: var(--muted);
  font-size: 20px;
  line-height: 1.7;
  margin: 0 0 32px 0;
  max-width: 540px;
}

.hero-stats {
  display: flex;
  gap: 32px;
  margin-top: 48px;
  flex-wrap: wrap;
}

.stat-item {
  display: flex;
  align-items: center;
  gap: 12px;
}

.stat-icon {
  width: 48px;
  height: 48px;
  background: var(--gold-light);
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--gold);
}

.stat-icon i {
  width: 24px;
  height: 24px;
}

.stat-number {
  font-size: 28px;
  font-weight: 700;
  color: var(--ink);
  line-height: 1;
}

.stat-label {
  font-size: 14px;
  color: var(--muted);
  margin-top: 4px;
}

.hero-visual {
  position: relative;
}

.hero-image {
  border-radius: 24px;
  overflow: hidden;
  box-shadow: var(--card-shadow-hover);
  position: relative;
}

.hero-image::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(217, 119, 6, 0.1) 0%, transparent 50%);
  z-index: 1;
}

.hero-image img {
  width: 100%;
  height: auto;
  display: block;
}

/* ===== SECTION UTILITIES ===== */
section {
  padding: var(--section-padding) 0;
}

.section-header {
  text-align: center;
  max-width: 800px;
  margin: 0 auto 64px;
}

.section-title-large {
  font-family: Poppins, sans-serif;
  font-size: 48px;
  font-weight: 700;
  line-height: 1.2;
  margin: 0 0 16px 0;
  letter-spacing: -1px;
  color: var(--ink);
}

.section-sub-large {
  font-size: 20px;
  line-height: 1.6;
  color: var(--muted);
  margin: 0;
}

.section-title {
  font-size: 32px;
  font-weight: 700;
  margin: 0 0 12px;
  color: var(--ink);
}

.section-sub {
  color: var(--muted);
  font-size: 18px;
  margin: 0;
}

.muted {
  color: var(--muted);
}

/* ===== FEATURES SECTION ===== */
.features-section {
  background: var(--surface);
  padding: var(--section-padding) 0;
  margin: 0 calc(-50vw + 50%);
  padding-left: calc(50vw - 50%);
  padding-right: calc(50vw - 50%);
}

.features-cards {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 32px;
  margin-top: 48px;
  max-width: var(--max-w);
  margin-left: auto;
  margin-right: auto;
  padding: 0 40px;
}

.feature-card {
  background: var(--surface);
  padding: 40px 32px;
  border-radius: 20px;
  box-shadow: var(--card-shadow);
  transition: all 0.3s ease;
  border: 1px solid var(--border);
  text-align: center;
}

.feature-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--card-shadow-hover);
  border-color: var(--gold-light);
}

.feature-icon {
  width: 64px;
  height: 64px;
  background: var(--gold-light);
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 24px;
  color: var(--gold);
}

.feature-icon i {
  width: 32px;
  height: 32px;
}

.feature-card h3 {
  font-size: 20px;
  font-weight: 700;
  margin: 0 0 12px 0;
  color: var(--ink);
}

.feature-card p {
  font-size: 15px;
  line-height: 1.6;
  color: var(--muted);
  margin: 0;
}

/* ===== TUTORS SECTION ===== */
.tutors-section {
  background: var(--bg);
  padding: var(--section-padding) 0;
}

.tutors-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
  margin-top: 48px;
}

.tutor {
  background: var(--surface);
  padding: 32px;
  border-radius: 16px;
  box-shadow: var(--card-shadow);
  display: flex;
  gap: 20px;
  align-items: flex-start;
  border: 1px solid var(--border);
  transition: all 0.3s ease;
}

.tutor:hover {
  transform: translateY(-4px);
  box-shadow: var(--card-shadow-hover);
}

.tutor h3 {
  font-size: 20px;
  font-weight: 700;
  margin: 0 0 8px 0;
  color: var(--ink);
}

.tutor p {
  font-size: 15px;
  line-height: 1.6;
  margin: 0;
}

.avatar {
  width: 100px;
  height: 100px;
  border-radius: 12px;
  background: var(--border);
  flex-shrink: 0;
  overflow: hidden;
}

.avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 12px;
}

/* ===== TWIN TEACHER SECTION ===== */
.twin-teacher-section {
  background: linear-gradient(135deg, var(--purple-light) 0%, var(--blue-light) 100%);
  padding: var(--section-padding) 0;
  position: relative;
  overflow: hidden;
  margin: 0 calc(-50vw + 50%);
  padding-left: calc(50vw - 50%);
  padding-right: calc(50vw - 50%);
}

.twin-teacher-section::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -10%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(139, 92, 246, 0.1) 0%, transparent 70%);
  border-radius: 50%;
}

.twin-teacher-container {
  position: relative;
  z-index: 1;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 40px;
}

.twin-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: white;
  padding: 8px 20px;
  border-radius: 999px;
  font-weight: 600;
  color: var(--purple);
  font-size: 14px;
  margin-bottom: 24px;
  box-shadow: 0 2px 8px rgba(139, 92, 246, 0.15);
}

.twin-badge i {
  width: 16px;
  height: 16px;
}

.twin-cards {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  margin-top: 48px;
}

.twin-card {
  background: white;
  padding: 48px 40px;
  border-radius: 24px;
  box-shadow: var(--card-shadow-hover);
  border: 2px solid transparent;
  transition: all 0.3s ease;
}

.twin-card:hover {
  transform: translateY(-8px);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.12);
}

.tutor-card {
  border-top: 4px solid var(--purple);
}

.tutor-card:hover {
  border-color: var(--purple);
  background: linear-gradient(to bottom, rgba(139, 92, 246, 0.02) 0%, white 100%);
}

.mentor-card {
  border-top: 4px solid var(--blue);
}

.mentor-card:hover {
  border-color: var(--blue);
  background: linear-gradient(to bottom, rgba(59, 130, 246, 0.02) 0%, white 100%);
}

.twin-icon {
  width: 72px;
  height: 72px;
  border-radius: 18px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 24px;
}

.tutor-card .twin-icon {
  background: var(--purple-light);
  color: var(--purple);
}

.mentor-card .twin-icon {
  background: var(--blue-light);
  color: var(--blue);
}

.twin-icon i {
  width: 36px;
  height: 36px;
}

.twin-card h3 {
  font-size: 24px;
  font-weight: 700;
  margin: 0 0 16px 0;
  color: var(--ink);
}

.twin-card p {
  font-size: 16px;
  line-height: 1.7;
  color: var(--muted);
  margin: 0 0 24px 0;
}

.twin-features {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.twin-features li {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 15px;
  color: var(--ink);
}

.twin-features li i {
  width: 20px;
  height: 20px;
  color: var(--green);
  flex-shrink: 0;
}

/* ===== BENEFITS SECTION ===== */
.benefits-section {
  background: var(--surface);
  padding: var(--section-padding) 0;
  margin: 0 calc(-50vw + 50%);
  padding-left: calc(50vw - 50%);
  padding-right: calc(50vw - 50%);
}

.benefits-cards {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 32px;
  margin-top: 48px;
  max-width: var(--max-w);
  margin-left: auto;
  margin-right: auto;
  padding: 0 40px;
}

.benefit-card {
  background: var(--bg);
  padding: 40px 32px;
  border-radius: 20px;
  border: 2px solid var(--border);
  transition: all 0.3s ease;
  text-align: center;
}

.benefit-card:hover {
  transform: translateY(-8px);
  border-color: var(--blue);
  background: white;
  box-shadow: var(--card-shadow-hover);
}

.benefit-icon {
  width: 64px;
  height: 64px;
  background: var(--blue-light);
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 24px;
  color: var(--blue);
}

.benefit-icon i {
  width: 32px;
  height: 32px;
}

.benefit-card h3 {
  font-size: 20px;
  font-weight: 700;
  margin: 0 0 12px 0;
  color: var(--ink);
}

.benefit-card p {
  font-size: 15px;
  line-height: 1.6;
  color: var(--muted);
  margin: 0;
}

/* ===== TESTIMONIALS SECTION ===== */
.testimonials-section {
  background: linear-gradient(180deg, var(--bg) 0%, var(--surface) 100%);
  padding: var(--section-padding) 0;
}

.testimonials-scroll-container {
  position: relative;
  margin-top: 48px;
  overflow: hidden;
}

.testimonials-scroll {
  display: flex;
  gap: 32px;
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  scroll-behavior: smooth;
  padding: 8px 0 32px 0;
  -webkit-overflow-scrolling: touch;
}

.testimonials-scroll::-webkit-scrollbar {
  height: 8px;
}

.testimonials-scroll::-webkit-scrollbar-track {
  background: var(--border);
  border-radius: 4px;
}

.testimonials-scroll::-webkit-scrollbar-thumb {
  background: var(--gold);
  border-radius: 4px;
}

.testimonial-card {
  flex: 0 0 420px;
  background: white;
  padding: 32px;
  border-radius: 20px;
  box-shadow: var(--card-shadow);
  scroll-snap-align: start;
  border: 1px solid var(--border);
  transition: all 0.3s ease;
}

.testimonial-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--card-shadow-hover);
}

.testimonial-header {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 20px;
}

.testimonial-avatar {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  overflow: hidden;
  border: 3px solid var(--gold-light);
}

.testimonial-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.testimonial-name {
  font-weight: 700;
  font-size: 16px;
  color: var(--ink);
  margin-bottom: 4px;
}

.testimonial-rating {
  display: flex;
  gap: 4px;
  color: var(--gold);
}

.testimonial-rating i {
  width: 16px;
  height: 16px;
  fill: currentColor;
}

.testimonial-card h4 {
  font-size: 18px;
  font-weight: 700;
  margin: 0 0 12px 0;
  color: var(--ink);
}

.testimonial-card p {
  font-size: 15px;
  line-height: 1.7;
  color: var(--muted);
  margin: 0;
  font-style: italic;
}

/* ===== FAQ SECTION ===== */
.faq-section {
  background: var(--surface);
  padding: var(--section-padding) 0;
}

.faq-container {
  max-width: 900px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.qa {
  background: var(--bg);
  padding: 32px;
  border-radius: 16px;
  border: 2px solid var(--border);
  transition: all 0.3s ease;
}

.qa:hover {
  border-color: var(--gold);
  background: white;
}

.qa button {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  border: none;
  background: transparent;
  padding: 0;
  font-weight: 700;
  font-size: 18px;
  color: var(--ink);
  text-align: left;
  cursor: pointer;
  line-height: 1.4;
}

.qa button::after {
  content: '+';
  font-size: 28px;
  font-weight: 400;
  color: var(--gold);
  flex-shrink: 0;
  margin-left: 20px;
  transition: transform 0.3s ease;
}

.qa button[aria-expanded="true"]::after {
  content: '−';
}

.qa .muted {
  font-size: 16px;
  line-height: 1.7;
  margin-top: 16px;
}

/* ===== BOOK DEMO SECTION ===== */
.book-demo-section {
  background: linear-gradient(135deg, var(--gold-light) 0%, var(--surface) 100%);
  padding: var(--section-padding) 0;
  position: relative;
  overflow: hidden;
  margin: 0 calc(-50vw + 50%);
  padding-left: calc(50vw - 50%);
  padding-right: calc(50vw - 50%);
}

.book-demo-section::before {
  content: '';
  position: absolute;
  top: -30%;
  left: -10%;
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, rgba(217, 119, 6, 0.1) 0%, transparent 70%);
  border-radius: 50%;
}

.book-demo-container {
  position: relative;
  z-index: 1;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 40px;
}

.book-demo-content {
  display: grid;
  grid-template-columns: 1fr 1.2fr;
  gap: 60px;
  align-items: start;
}

.book-demo-info .section-header {
  text-align: left;
  margin-bottom: 48px;
}

.demo-benefits {
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.demo-benefit {
  display: flex;
  gap: 20px;
  align-items: flex-start;
}

.demo-benefit-icon {
  width: 56px;
  height: 56px;
  background: white;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--gold);
  flex-shrink: 0;
  box-shadow: 0 4px 12px rgba(217, 119, 6, 0.15);
}

.demo-benefit-icon i {
  width: 28px;
  height: 28px;
}

.demo-benefit h4 {
  font-size: 20px;
  font-weight: 700;
  margin: 0 0 8px 0;
  color: var(--ink);
}

.demo-benefit p {
  font-size: 15px;
  line-height: 1.6;
  color: var(--muted);
  margin: 0;
}

.book-demo-form-wrapper {
  position: sticky;
  top: 100px;
}

.book-demo-form {
  background: white;
  border-radius: 24px;
  overflow: hidden;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.1);
  border: 3px solid var(--gold);
  padding: 8px;
}

.book-demo-form iframe {
  border-radius: 16px;
}

/* ===== FOOTER ===== */
.footer {
  background: var(--ink);
  color: white;
  padding: 80px 0 32px;
  margin-top: var(--section-padding);
}

.footer-content {
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  gap: 80px;
  margin-bottom: 60px;
}

.footer-brand {
  max-width: 400px;
}

.footer-logo {
  margin-bottom: 16px;
}

.footer-logo-image {
  height: 48px;
  width: auto;
  display: block;
  filter: brightness(0) invert(1);
}

.footer-tagline {
  color: var(--muted-light);
  font-size: 16px;
  line-height: 1.6;
  margin: 0 0 24px 0;
}

.footer-trust {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
}

.trust-item {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--gold-light);
  font-weight: 600;
  font-size: 14px;
}

.trust-item i {
  width: 20px;
  height: 20px;
}

.footer-links {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 40px;
}

.footer-column h4 {
  font-size: 16px;
  font-weight: 700;
  margin: 0 0 20px 0;
  color: white;
}

.footer-column a {
  display: block;
  color: var(--muted-light);
  font-size: 14px;
  margin-bottom: 12px;
  transition: color 0.2s ease;
}

.footer-column a:hover {
  color: var(--gold);
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: 32px;
  text-align: center;
}

.footer-bottom p {
  color: var(--muted-light);
  font-size: 14px;
  margin: 8px 0;
}

/* ===== RESPONSIVE DESIGN ===== */
@media (max-width: 1200px) {
  :root {
    --section-padding: 80px;
  }

  .container {
    padding: 0 32px;
  }

  h1 {
    font-size: 52px;
  }

  .section-title-large {
    font-size: 40px;
  }

  .hero {
    gap: 60px;
  }

  .features-cards,
  .benefits-cards {
    grid-template-columns: repeat(2, 1fr);
    padding: 0 32px;
  }

  .twin-teacher-container,
  .book-demo-container {
    padding: 0 32px;
  }

  .footer-content {
    grid-template-columns: 1fr;
    gap: 60px;
  }

  .footer-links {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 968px) {
  :root {
    --section-padding: 60px;
  }

  .nav-links {
    display: none;
  }

  .hero {
    grid-template-columns: 1fr;
    min-height: auto;
    padding: 60px 0;
    gap: 48px;
  }

  h1 {
    font-size: 44px;
  }

  .section-title-large {
    font-size: 36px;
  }

  .section-sub-large {
    font-size: 18px;
  }

  .tutors-grid {
    grid-template-columns: 1fr;
  }

  .twin-cards {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .book-demo-content {
    grid-template-columns: 1fr;
    gap: 48px;
  }

  .book-demo-form-wrapper {
    position: static;
  }

  .footer-links {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 640px) {
  :root {
    --section-padding: 48px;
  }

  .container {
    padding: 0 20px;
  }

  h1 {
    font-size: 36px;
    letter-spacing: -1px;
  }

  .lead {
    font-size: 18px;
  }

  .section-title-large {
    font-size: 32px;
  }

  .section-sub-large {
    font-size: 16px;
  }

  .hero-stats {
    flex-direction: column;
    gap: 20px;
    margin-top: 32px;
  }

  .features-cards,
  .benefits-cards {
    grid-template-columns: 1fr;
    gap: 24px;
    padding: 0 20px;
  }

  .twin-teacher-container,
  .book-demo-container {
    padding: 0 20px;
  }

  .testimonial-card {
    flex: 0 0 320px;
    padding: 24px;
  }

  .qa {
    padding: 24px;
  }

  .qa button {
    font-size: 16px;
  }

  .footer-links {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .footer-content {
    gap: 48px;
  }
}

/* ===== UTILITIES ===== */
.center {
  display: flex;
  align-items: center;
  justify-content: center;
}