/* ==========================================================================
   SudokAI - Modern Cyber Dark Design System
   https://sudokai.nl
   ========================================================================== */

:root {
  --color-bg-dark: #07080d;
  --color-bg-darker: #040508;
  --color-card-bg: rgba(18, 20, 32, 0.75);
  --color-card-border: rgba(255, 255, 255, 0.08);
  --color-card-hover: rgba(26, 29, 46, 0.85);

  --neon-cyan: #00f0ff;
  --neon-purple: #b026ff;
  --neon-orange: #ff9f0a;
  --neon-green: #00ff88;
  --neon-red: #ff3b30;

  --neon-cyan-glow: rgba(0, 240, 255, 0.35);
  --neon-purple-glow: rgba(176, 38, 255, 0.3);
  --neon-orange-glow: rgba(255, 159, 10, 0.35);

  --text-primary: #ffffff;
  --text-secondary: #9ba1b8;
  --text-muted: #5e647e;

  --font-display: 'Outfit', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: 'SF Mono', Menlo, Monaco, Consolas, monospace;

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-xl: 32px;

  --container-max: 1200px;
  --transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

/* Reset & Base Styles */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  color-scheme: dark;
  font-size: 16px;
}

body {
  background-color: var(--color-bg-dark);
  color: var(--text-primary);
  font-family: var(--font-body);
  line-height: 1.65;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  background-image: 
    radial-gradient(circle at 50% 0%, rgba(0, 240, 255, 0.12), transparent 45%),
    radial-gradient(circle at 85% 20%, rgba(176, 38, 255, 0.1), transparent 40%),
    radial-gradient(circle at 15% 60%, rgba(0, 240, 255, 0.08), transparent 35%);
  background-repeat: no-repeat;
}

/* Typography */
h1, h2, h3, h4, .brand-logo {
  font-family: var(--font-display);
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -0.02em;
}

h1 {
  font-size: clamp(2.4rem, 5.5vw, 4.2rem);
}

h2 {
  font-size: clamp(1.8rem, 3.8vw, 2.8rem);
}

h3 {
  font-size: 1.4rem;
}

p {
  color: var(--text-secondary);
}

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

/* Layout Utilities */
.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
}

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

.text-center {
  text-align: center;
}

/* Neon Text Gradient */
.gradient-text {
  background: linear-gradient(135deg, #ffffff 10%, var(--neon-cyan) 60%, #ffffff 90%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  display: inline-block;
}

.gradient-text-warm {
  background: linear-gradient(135deg, #ffffff 10%, var(--neon-orange) 60%, #ff5e3a 90%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  display: inline-block;
}

/* Header & Navigation */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: 18px 0;
  background: rgba(7, 8, 13, 0.7);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--color-card-border);
  transition: var(--transition);
}

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

.brand-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.5rem;
  color: #ffffff;
}

.brand-icon {
  width: 38px;
  height: 38px;
  border-radius: 10px;
  box-shadow: 0 0 16px var(--neon-cyan-glow);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
  list-style: none;
}

.nav-link {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.nav-link:hover {
  color: var(--neon-cyan);
  text-shadow: 0 0 12px var(--neon-cyan-glow);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

/* Language Switcher */
.lang-switcher {
  display: inline-flex;
  align-items: center;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--color-card-border);
  border-radius: 999px;
  padding: 3px;
  gap: 3px;
}

.lang-btn {
  background: transparent;
  border: none;
  color: var(--text-secondary);
  font-family: var(--font-display);
  font-size: 0.82rem;
  font-weight: 700;
  padding: 5px 10px;
  border-radius: 999px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 5px;
  transition: var(--transition);
}

.lang-btn:hover {
  color: #ffffff;
}

.lang-btn.active {
  background: var(--neon-cyan);
  color: #040508;
  box-shadow: 0 0 14px var(--neon-cyan-glow);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 13px 26px;
  border-radius: var(--radius-md);
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  border: none;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.btn-primary {
  background: linear-gradient(135deg, var(--neon-cyan), #0099ff);
  color: #040508;
  box-shadow: 0 0 24px var(--neon-cyan-glow);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 0 32px rgba(0, 240, 255, 0.6);
}

.btn-secondary {
  background: var(--color-card-bg);
  border: 1px solid var(--color-card-border);
  color: #ffffff;
  backdrop-filter: blur(12px);
}

.btn-secondary:hover {
  border-color: var(--neon-purple);
  box-shadow: 0 0 20px var(--neon-purple-glow);
  transform: translateY(-2px);
}

.btn-icon {
  width: 20px;
  height: 20px;
  fill: currentColor;
}

/* Hero Section */
.hero {
  padding-top: 170px;
  padding-bottom: 90px;
  text-align: center;
  position: relative;
}

.hero-pill {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  border-radius: 999px;
  background: rgba(0, 240, 255, 0.08);
  border: 1px solid rgba(0, 240, 255, 0.3);
  color: var(--neon-cyan);
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 24px;
  box-shadow: 0 0 16px rgba(0, 240, 255, 0.15);
}

.hero-pill-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--neon-cyan);
  box-shadow: 0 0 8px var(--neon-cyan);
  animation: pulse 2s infinite;
}

.hero-title {
  max-width: 880px;
  margin: 0 auto 24px;
}

.hero-subtitle {
  max-width: 680px;
  margin: 0 auto 40px;
  font-size: 1.2rem;
  line-height: 1.6;
}

.hero-cta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 18px;
  margin-bottom: 64px;
  flex-wrap: wrap;
}

/* App Showcase Showcase Display */
.showcase-stage {
  position: relative;
  max-width: 1040px;
  margin: 0 auto;
  display: flex;
  justify-content: center;
  align-items: flex-end;
  gap: 32px;
}

.device-frame {
  background: #111420;
  border-radius: 36px;
  padding: 10px;
  border: 2px solid rgba(255, 255, 255, 0.12);
  box-shadow: 
    0 24px 70px rgba(0, 0, 0, 0.8),
    0 0 40px rgba(0, 240, 255, 0.2);
  transition: var(--transition);
  position: relative;
}

.device-frame:hover {
  transform: translateY(-6px);
  box-shadow: 
    0 32px 80px rgba(0, 0, 0, 0.9),
    0 0 50px rgba(0, 240, 255, 0.35);
}

.device-screen {
  border-radius: 28px;
  overflow: hidden;
  display: block;
  width: 100%;
  height: auto;
}

.device-iphone {
  width: 320px;
  z-index: 2;
}

.device-ipad {
  width: 580px;
  z-index: 1;
  border-color: rgba(176, 38, 255, 0.35);
  box-shadow: 
    0 24px 70px rgba(0, 0, 0, 0.8),
    0 0 40px rgba(176, 38, 255, 0.25);
}

/* Features Grid */
.features-header {
  max-width: 660px;
  margin: 0 auto 60px;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
  gap: 28px;
}

.feature-card {
  background: var(--color-card-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius-lg);
  padding: 36px 30px;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.feature-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--neon-cyan), transparent);
  opacity: 0;
  transition: var(--transition);
}

.feature-card:hover {
  background: var(--color-card-hover);
  border-color: rgba(0, 240, 255, 0.3);
  transform: translateY(-5px);
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.5), 0 0 30px rgba(0, 240, 255, 0.15);
}

.feature-card:hover::before {
  opacity: 1;
}

.feature-icon-box {
  width: 54px;
  height: 54px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 22px;
  font-size: 1.5rem;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.08);
}

.feature-icon-box.cyan {
  color: var(--neon-cyan);
  background: rgba(0, 240, 255, 0.1);
  border-color: rgba(0, 240, 255, 0.25);
}

.feature-icon-box.purple {
  color: var(--neon-purple);
  background: rgba(176, 38, 255, 0.1);
  border-color: rgba(176, 38, 255, 0.25);
}

.feature-icon-box.orange {
  color: var(--neon-orange);
  background: rgba(255, 159, 10, 0.1);
  border-color: rgba(255, 159, 10, 0.25);
}

.feature-icon-box.green {
  color: var(--neon-green);
  background: rgba(0, 255, 136, 0.1);
  border-color: rgba(0, 255, 136, 0.25);
}

.feature-card h3 {
  margin-bottom: 12px;
  color: #ffffff;
}

/* 3-Step AI Tutor Interactive Section */
.tutor-section {
  background: linear-gradient(180deg, transparent, rgba(176, 38, 255, 0.05), transparent);
}

.tutor-box {
  background: rgba(14, 16, 26, 0.85);
  border: 1px solid rgba(0, 240, 255, 0.2);
  border-radius: var(--radius-xl);
  padding: 48px;
  box-shadow: 0 0 50px rgba(0, 240, 255, 0.1);
  max-width: 980px;
  margin: 0 auto;
}

.step-flow {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-top: 40px;
  position: relative;
}

.step-card {
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--radius-md);
  padding: 24px;
  text-align: left;
  transition: var(--transition);
}

.step-card:hover {
  border-color: var(--neon-cyan);
  background: rgba(0, 240, 255, 0.04);
}

.step-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  padding: 4px 10px;
  border-radius: 6px;
  margin-bottom: 14px;
}

.step-badge.s1 {
  background: rgba(0, 240, 255, 0.15);
  color: var(--neon-cyan);
}

.step-badge.s2 {
  background: rgba(176, 38, 255, 0.15);
  color: var(--neon-purple);
}

.step-badge.s3 {
  background: rgba(255, 159, 10, 0.15);
  color: var(--neon-orange);
}

/* Techniques Grid */
.techniques-list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
  max-width: 900px;
  margin: 36px auto 0;
}

.tech-tag {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.09);
  padding: 10px 18px;
  border-radius: 999px;
  font-size: 0.9rem;
  font-weight: 600;
  color: #e2e4f0;
  transition: var(--transition);
}

.tech-tag:hover {
  background: rgba(0, 240, 255, 0.12);
  border-color: var(--neon-cyan);
  color: #ffffff;
  transform: translateY(-2px);
  box-shadow: 0 0 16px var(--neon-cyan-glow);
}

/* CTA Banner */
.cta-banner {
  background: linear-gradient(135deg, rgba(0, 240, 255, 0.15), rgba(176, 38, 255, 0.15));
  border: 1px solid rgba(0, 240, 255, 0.3);
  border-radius: var(--radius-xl);
  padding: 64px 32px;
  text-align: center;
  box-shadow: 0 0 60px rgba(0, 240, 255, 0.15);
  margin-top: 40px;
}

/* Footer */
.footer {
  border-top: 1px solid var(--color-card-border);
  padding: 60px 0 36px;
  background: var(--color-bg-darker);
  font-size: 0.9rem;
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 24px;
  margin-bottom: 36px;
}

.footer-links {
  display: flex;
  gap: 24px;
  list-style: none;
}

.footer-links a:hover {
  color: var(--neon-cyan);
}

.footer-copyright {
  border-top: 1px solid rgba(255, 255, 255, 0.04);
  padding-top: 24px;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* Privacy Page Specifics */
.legal-page {
  padding-top: 150px;
  padding-bottom: 90px;
}

.legal-card {
  background: var(--color-card-bg);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius-xl);
  padding: 48px;
  backdrop-filter: blur(20px);
  max-width: 860px;
  margin: 0 auto;
}

.legal-card h1 {
  font-size: 2.4rem;
  margin-bottom: 8px;
}

.legal-card .meta-date {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--neon-cyan);
  margin-bottom: 36px;
}

.legal-card h2 {
  font-size: 1.4rem;
  margin-top: 36px;
  margin-bottom: 12px;
  color: #ffffff;
}

.legal-card p, .legal-card ul {
  margin-bottom: 16px;
  color: var(--text-secondary);
}

.legal-card ul {
  padding-left: 24px;
}

.legal-card li {
  margin-bottom: 8px;
}

.legal-highlight-box {
  background: rgba(0, 255, 136, 0.08);
  border: 1px solid rgba(0, 255, 136, 0.3);
  border-radius: var(--radius-md);
  padding: 20px;
  margin: 24px 0;
  color: #c7ffe0;
}

/* Keyframes */
@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.4; transform: scale(0.85); }
}

/* Responsive Media Queries */
@media (max-width: 900px) {
  .showcase-stage {
    flex-direction: column;
    align-items: center;
  }
  .device-ipad {
    width: 100%;
    max-width: 520px;
  }
  .device-iphone {
    width: 260px;
  }
  .step-flow {
    grid-template-columns: 1fr;
  }
  .nav-links {
    display: none;
  }
}

@media (max-width: 600px) {
  .section {
    padding: 60px 0;
  }
  .hero {
    padding-top: 130px;
  }
  .tutor-box {
    padding: 28px 20px;
  }
  .legal-card {
    padding: 28px 20px;
  }
}