/* CSS Variables for Premium Dark/Light Theme & Neon Accents */
:root {
  --bg-color: #0f172a; /* Dark charcoal */
  --surface-color: #1e293b;
  --surface-glow: rgba(30, 41, 59, 0.7);
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  
  --primary-color: #4f46e5; /* Electric blue */
  --primary-hover: #4338ca;
  --accent-color: #10b981; /* Neon green */
  --accent-glow: rgba(16, 185, 129, 0.4);
  --danger-color: #ef4444;
  --danger-glow: rgba(239, 68, 68, 0.4);
  
  --font-sans: 'Inter', sans-serif;
  --font-display: 'Syne', sans-serif;
  
  --radius-sm: 8px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --radius-pill: 9999px;
  
  --glass-bg: rgba(30, 41, 59, 0.6);
  --glass-border: rgba(255, 255, 255, 0.1);
  --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
  
  --transition-fast: 0.15s ease;
  --transition-smooth: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Light Mode (Optional, default dark is prioritized) */
body.light-mode {
  --bg-color: #f8fafc;
  --surface-color: #ffffff;
  --text-main: #0f172a;
  --text-muted: #64748b;
  --glass-bg: rgba(255, 255, 255, 0.7);
  --glass-border: rgba(0, 0, 0, 0.05);
  --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.05);
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-color);
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
  transition: background-color var(--transition-smooth), color var(--transition-smooth);
}

a {
  text-decoration: none;
  color: inherit;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Typography Utilities */
.gradient-text {
  background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* Buttons */
.btn-primary, .btn-secondary, .btn-nav {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 24px;
  border-radius: var(--radius-pill);
  font-weight: 600;
  font-size: 1rem;
  transition: all var(--transition-fast);
  cursor: pointer;
  border: none;
  gap: 8px;
}

.btn-primary {
  background-color: var(--primary-color);
  color: white;
  box-shadow: 0 4px 14px rgba(79, 70, 229, 0.4);
}

.btn-primary:hover {
  background-color: var(--primary-hover);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(79, 70, 229, 0.6);
}

.btn-secondary {
  background-color: var(--glass-bg);
  border: 1px solid var(--glass-border);
  color: var(--text-main);
  backdrop-filter: blur(10px);
}

.btn-secondary:hover {
  background-color: var(--surface-color);
  transform: translateY(-2px);
}

.btn-nav {
  padding: 8px 16px;
  background-color: var(--primary-color);
  color: white;
  font-size: 0.9rem;
}

.btn-large {
  padding: 16px 32px;
  font-size: 1.1rem;
}

/* Navbar */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: var(--glass-bg);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--glass-border);
}

.nav-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 16px 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 800;
}

.logo-accent {
  color: var(--accent-color);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 24px;
  font-weight: 500;
}

.nav-links a:not(.btn-nav):hover {
  color: var(--primary-color);
}

.hamburger {
  display: none;
  background: none;
  border: none;
  color: var(--text-main);
  font-size: 1.5rem;
  cursor: pointer;
}

/* Hero Section */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 120px 24px 60px;
  overflow: hidden;
}

.hero-bg-glow {
  position: absolute;
  width: 600px;
  height: 600px;
  border-radius: 50%;
  filter: blur(100px);
  opacity: 0.15;
  z-index: 0;
}

.glow-blue { background-color: var(--primary-color); top: -100px; left: -100px; }
.glow-green { background-color: var(--accent-color); bottom: -100px; right: -100px; }

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
}

.hero-badge {
  display: inline-block;
  padding: 6px 16px;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-pill);
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 24px;
  backdrop-filter: blur(10px);
}

.hero-headline {
  font-family: var(--font-display);
  font-size: clamp(2.5rem, 5vw, 4.5rem);
  line-height: 1.1;
  margin-bottom: 24px;
  letter-spacing: -0.02em;
}

.hero-sub {
  font-size: clamp(1.125rem, 2vw, 1.25rem);
  color: var(--text-muted);
  margin-bottom: 40px;
}

.hero-cta {
  display: flex;
  gap: 16px;
  justify-content: center;
  margin-bottom: 60px;
}

/* Live Stats */
.live-stats {
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}

.stat-pill {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--surface-color);
  padding: 8px 16px;
  border-radius: var(--radius-pill);
  font-size: 0.875rem;
  border: 1px solid var(--glass-border);
}

.stat-num { font-weight: 700; }
.stat-label { color: var(--text-muted); }

.pulse-green {
  width: 8px;
  height: 8px;
  background-color: var(--accent-color);
  border-radius: 50%;
  box-shadow: 0 0 0 0 var(--accent-glow);
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0% { transform: scale(0.95); box-shadow: 0 0 0 0 var(--accent-glow); }
  70% { transform: scale(1); box-shadow: 0 0 0 6px rgba(16, 185, 129, 0); }
  100% { transform: scale(0.95); box-shadow: 0 0 0 0 rgba(16, 185, 129, 0); }
}

/* Floating Cards Animation */
.floating-card {
  position: absolute;
  background: var(--surface-color);
  padding: 12px 20px;
  border-radius: var(--radius-md);
  border: 1px solid var(--glass-border);
  box-shadow: var(--glass-shadow);
  font-size: 0.875rem;
  font-weight: 600;
  z-index: 0;
  animation: float 6s ease-in-out infinite;
  opacity: 0.8;
  display: none; /* Hidden on mobile */
}

@media (min-width: 1024px) {
  .floating-card { display: block; }
  .fc1 { top: 20%; left: 10%; animation-delay: 0s; }
  .fc2 { top: 60%; right: 10%; animation-delay: 2s; }
  .fc3 { bottom: 15%; left: 15%; animation-delay: 4s; }
}

@keyframes float {
  0% { transform: translateY(0px); }
  50% { transform: translateY(-20px); }
  100% { transform: translateY(0px); }
}

/* Sections General */
section {
  padding: 80px 0;
}

.section-label {
  color: var(--primary-color);
  font-weight: 700;
  font-size: 0.875rem;
  letter-spacing: 0.1em;
  margin-bottom: 8px;
  text-align: center;
}

.section-title {
  font-family: var(--font-display);
  font-size: clamp(2rem, 3vw, 3rem);
  text-align: center;
  margin-bottom: 48px;
}

/* Stats Banner */
.stats-banner {
  background: var(--surface-color);
  border-top: 1px solid var(--glass-border);
  border-bottom: 1px solid var(--glass-border);
  padding: 40px 0;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 32px;
  text-align: center;
}

.stat-val {
  font-family: var(--font-display);
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--text-main);
  margin-bottom: 8px;
}

/* Features Grid */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 24px;
}

.feature-card {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  padding: 32px;
  border-radius: var(--radius-lg);
  position: relative;
  overflow: hidden;
  transition: transform var(--transition-smooth);
}

.feature-card:hover {
  transform: translateY(-5px);
  background: var(--surface-color);
}

.glow-card {
  box-shadow: 0 0 30px rgba(79, 70, 229, 0.15);
  border-color: rgba(79, 70, 229, 0.3);
}

.feat-icon {
  font-size: 2.5rem;
  margin-bottom: 16px;
}

.feature-card h3 {
  font-size: 1.25rem;
  margin-bottom: 12px;
}

.feature-card p {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 24px;
}

.feat-tag {
  position: absolute;
  top: 24px;
  right: 24px;
  background: rgba(255,255,255,0.1);
  padding: 4px 12px;
  border-radius: var(--radius-pill);
  font-size: 0.75rem;
  font-weight: 600;
}

/* Subjects Section */
.subjects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 24px;
}

.subject-card {
  background: var(--surface-color);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  padding: 32px;
  display: block;
  transition: all var(--transition-smooth);
}

.subject-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--glass-shadow);
  border-color: var(--primary-color);
}

.subj-emoji { font-size: 3rem; margin-bottom: 16px; }
.subj-name { font-size: 1.5rem; font-weight: 700; margin-bottom: 4px; }
.subj-count { color: var(--text-muted); font-size: 0.875rem; margin-bottom: 24px; }

.subj-bar {
  height: 6px;
  background: rgba(255,255,255,0.1);
  border-radius: var(--radius-pill);
  margin-bottom: 16px;
  overflow: hidden;
}

.subj-fill {
  height: 100%;
  background: var(--primary-color);
  border-radius: var(--radius-pill);
}

.bio-card .subj-fill { background: #10b981; }
.phy-card .subj-fill { background: #3b82f6; }
.chem-card .subj-fill { background: #8b5cf6; }

.subj-tag {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 600;
}

/* Testimonials */
.testimonials-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 24px;
}

.testi-card {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  padding: 32px;
}

.testi-featured {
  background: var(--surface-color);
  border-color: var(--primary-color);
  transform: scale(1.05);
  box-shadow: 0 20px 40px rgba(0,0,0,0.2);
}

.testi-stars { margin-bottom: 16px; letter-spacing: 2px; }
.testi-card p { font-size: 1rem; margin-bottom: 24px; font-style: italic; }

.testi-author {
  display: flex;
  align-items: center;
  gap: 12px;
}

.testi-avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  color: white;
}

.testi-name { font-weight: 600; font-size: 0.95rem; }
.testi-score { color: var(--accent-color); font-size: 0.85rem; font-weight: 700; }

/* Final CTA */
.final-cta-section {
  text-align: center;
  position: relative;
  overflow: hidden;
  padding: 100px 0;
}

.final-cta-content {
  position: relative;
  z-index: 1;
}

.cta-badge {
  display: inline-block;
  padding: 6px 16px;
  background: var(--danger-glow);
  color: #fca5a5;
  border-radius: var(--radius-pill);
  font-weight: 600;
  margin-bottom: 24px;
}

.final-cta-section h2 {
  font-family: var(--font-display);
  font-size: clamp(2rem, 4vw, 3.5rem);
  margin-bottom: 16px;
}

.final-cta-section p {
  font-size: 1.125rem;
  color: var(--text-muted);
  margin-bottom: 40px;
}

/* Footer */
.footer {
  background: #0b1120;
  padding: 60px 0 40px;
  border-top: 1px solid var(--glass-border);
}

.footer-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 32px;
}

.footer-links {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
  justify-content: center;
}

.footer-links a {
  color: var(--text-muted);
  font-size: 0.9rem;
  transition: color var(--transition-fast);
}

.footer-links a:hover { color: var(--text-main); }
.footer-copy { color: var(--text-muted); font-size: 0.85rem; }

/* Responsive */
@media (max-width: 768px) {
  .nav-links {
    display: none; /* Ideally toggle this with JS */
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background: var(--surface-color);
    flex-direction: column;
    padding: 24px;
    border-bottom: 1px solid var(--glass-border);
  }
  .hamburger { display: block; }
  .hero-cta { flex-direction: column; width: 100%; max-width: 300px; margin: 0 auto 40px; }
  .testi-featured { transform: scale(1); }
}