:root {
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --secondary: #ec4899;
  --accent: #06b6d4;
  --dark: #0f172a;
  --dark-light: #1e293b;
  --light: #f8fafc;
  --gray: #64748b;
  --success: #10b981;
  --warning: #f59e0b;

  --gradient-1: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --gradient-2: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
  --gradient-3: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
  --gradient-4: linear-gradient(135deg, #43e97b 0%, #38f9d7 100%);
  --gradient-hero: linear-gradient(135deg, #1e1b4b 0%, #312e81 30%, #4c1d95 70%, #5b21b6 100%);

  --glass: rgba(255, 255, 255, 0.1);
  --glass-border: rgba(255, 255, 255, 0.2);
  --shadow-lg: 0 25px 50px -12px rgba(0, 0, 0, 0.4);
  --shadow-glow: 0 0 40px rgba(99, 102, 241, 0.4);

  --transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  --transition-fast: all 0.2s ease;

  --radius-lg: 24px;
  --radius-xl: 32px;
  --radius-full: 9999px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  background: var(--dark);
  color: var(--light);
  line-height: 1.6;
  overflow-x: hidden;
  position: relative;
}

.bg-animated {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -2;
  background: var(--gradient-hero);
  overflow: hidden;
}

.bg-animated::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background:
    radial-gradient(circle at 20% 80%, rgba(124, 58, 237, 0.3) 0%, transparent 50%),
    radial-gradient(circle at 80% 20%, rgba(236, 72, 153, 0.3) 0%, transparent 50%),
    radial-gradient(circle at 40% 40%, rgba(6, 182, 212, 0.2) 0%, transparent 40%);
  animation: floatBg 20s ease-in-out infinite;
}

@keyframes floatBg {
  0%, 100% { transform: translate(0, 0) rotate(0deg); }
  25% { transform: translate(2%, 2%) rotate(0.5deg); }
  50% { transform: translate(0, 4%) rotate(0deg); }
  75% { transform: translate(-2%, 2%) rotate(-0.5deg); }
}

.particles {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -1;
  pointer-events: none;
}

.particle {
  position: absolute;
  width: 4px;
  height: 4px;
  background: rgba(255, 255, 255, 0.6);
  border-radius: 50%;
  animation: float 15s infinite linear;
  opacity: 0;
}

@keyframes float {
  0% { transform: translateY(100vh) scale(0); opacity: 0; }
  10% { opacity: 1; }
  90% { opacity: 1; }
  100% { transform: translateY(-100px) scale(1); opacity: 0; }
}

.glass {
  background: var(--glass);
  backdrop-filter: blur(20px);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
}

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

h1, h2, h3, h4 {
  font-weight: 700;
  line-height: 1.2;
}

h1 {
  font-size: clamp(2.5rem, 5vw, 4rem);
  background: linear-gradient(135deg, #fff 0%, #c7d2fe 50%, #fff 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

h2 {
  font-size: clamp(1.75rem, 3vw, 2.5rem);
  margin-bottom: 1rem;
}

h3 {
  font-size: 1.25rem;
  margin-bottom: 0.5rem;
}

p {
  color: rgba(255, 255, 255, 0.85);
  margin-bottom: 1rem;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: var(--transition-fast);
}

a:hover {
  color: #22d3ee;
}

section {
  padding: 100px 0;
  position: relative;
}

header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: 16px 0;
  transition: var(--transition);
}

header.scrolled {
  background: rgba(15, 23, 42, 0.95);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--glass-border);
  padding: 12px 0;
}

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

.logo {
  font-size: 1.5rem;
  font-weight: 800;
  background: linear-gradient(135deg, #818cf8, #c084fc);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  display: flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
}

.logo-icon {
  width: 32px;
  height: 32px;
  background: var(--gradient-1);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 900;
  color: white;
  font-size: 1rem;
}

.nav-links {
  display: flex;
  gap: 20px;
  list-style: none;
}

.nav-links a {
  color: rgba(255, 255, 255, 0.85);
  font-weight: 500;
  position: relative;
  padding: 4px 0;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gradient-1);
  transition: var(--transition-fast);
  border-radius: 2px;
}

.nav-links a:hover::after {
  width: 100%;
}

.nav-cta {
  background: var(--gradient-1);
  color: white;
  padding: 12px 28px;
  border-radius: var(--radius-full);
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: 0 4px 20px rgba(99, 102, 241, 0.4);
  text-decoration: none;
}

.nav-cta:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(99, 102, 241, 0.6);
  color: white;
}

.back-link {
  color: rgba(255, 255, 255, 0.85);
  text-decoration: none;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 8px;
  transition: var(--transition);
}

.back-link:hover {
  color: var(--accent);
}

.btn-primary {
  background: var(--gradient-1);
  color: white;
  padding: 14px 28px;
  border-radius: var(--radius-full);
  font-weight: 600;
  font-size: 1.1rem;
  border: none;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: var(--shadow-glow);
  display: inline-flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
}

.btn-primary:hover {
  transform: translateY(-3px);
  box-shadow: 0 0 60px rgba(99, 102, 241, 0.6);
  color: white;
}

.btn-secondary {
  background: transparent;
  color: white;
  padding: 14px 28px;
  border-radius: var(--radius-full);
  font-weight: 600;
  font-size: 1.1rem;
  border: 2px solid rgba(255, 255, 255, 0.3);
  cursor: pointer;
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
}

.btn-secondary:hover {
  border-color: rgba(255, 255, 255, 0.6);
  background: rgba(255, 255, 255, 0.1);
  color: white;
}

.section-header {
  text-align: center;
  max-width: 700px;
  margin: 0 auto 60px;
}

.section-header h2 {
  position: relative;
  display: inline-block;
}

.section-header h2::after {
  content: '';
  position: absolute;
  bottom: -16px;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 4px;
  background: var(--gradient-1);
  border-radius: 2px;
}

.animate-on-scroll {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.animate-on-scroll.visible {
  opacity: 1;
  transform: translateY(0);
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(30px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes pulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(99, 102, 241, 0.4); }
  50% { box-shadow: 0 0 0 10px rgba(99, 102, 241, 0); }
}

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  color: white;
  font-size: 1.5rem;
  cursor: pointer;
}

/* Fullscreen button (always visible) */
.fs-control {
  position: fixed;
  right: 24px;
  top: 100px;
  z-index: 999;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

/* Scroll controls (наверх / вниз) */
.scroll-controls {
  position: fixed;
  right: 24px;
  top: 152px;
  z-index: 999;
  display: flex;
  flex-direction: column;
  gap: 8px;
  opacity: 0;
  transform: translateY(16px);
  transition: all 0.3s ease;
  pointer-events: none;
}

.scroll-controls.visible {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.scroll-btn {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(12px);
  border: 1px solid rgba(255, 255, 255, 0.2);
  color: rgba(255, 255, 255, 0.8);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.25s ease;
}

.scroll-btn:hover {
  background: rgba(99, 102, 241, 0.2);
  border-color: #6366f1;
  color: #818cf8;
  transform: scale(1.1);
}

.scroll-btn svg {
  width: 20px;
  height: 20px;
  stroke: currentColor;
  fill: none;
  stroke-width: 2.5;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.fs-btn svg {
  width: 18px;
  height: 18px;
}

@media (max-width: 768px) {
  .fs-control { right: 16px; top: 80px; }
  .scroll-controls { right: 16px; top: 126px; }
  .scroll-btn { width: 38px; height: 38px; }
  .scroll-btn svg { width: 16px; height: 16px; }
}

@media (max-width: 1024px) {
  section {
    padding: 80px 0;
  }
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
  }

  .mobile-menu-btn {
    display: block;
  }

  section {
    padding: 70px 0;
  }
}