/* ============================================
   Sensein Landing Page Styles
   Dark theme | Mobile-first | Modern design
   ============================================ */

/* --- Custom Properties --- */
:root {
  --bg-primary: #0D0D0D;
  --bg-card: #1A1A1A;
  --bg-card-hover: #222222;
  --accent-blue: #007AFF;
  --accent-blue-glow: rgba(0, 122, 255, 0.25);
  --accent-orange: #FF9500;
  --accent-orange-glow: rgba(255, 149, 0, 0.25);
  --accent-green: #30D158;
  --text-primary: #FFFFFF;
  --text-secondary: #888888;
  --text-tertiary: #555555;
  --border-subtle: rgba(255, 255, 255, 0.06);
  --border-card: rgba(255, 255, 255, 0.08);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-xl: 24px;
  --shadow-card: 0 4px 24px rgba(0, 0, 0, 0.3);
  --shadow-glow-blue: 0 0 40px rgba(0, 122, 255, 0.15);
  --shadow-glow-orange: 0 0 40px rgba(255, 149, 0, 0.15);
  --transition-fast: 0.2s ease;
  --transition-med: 0.35s ease;
  --transition-slow: 0.6s cubic-bezier(0.16, 1, 0.3, 1);
  --container-max: 1200px;
  --section-padding: 80px 0;
}

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

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

ul {
  list-style: none;
}

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

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

/* --- Scroll Animations --- */
.fade-up {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity var(--transition-slow), transform var(--transition-slow);
}

.fade-up.visible {
  opacity: 1;
  transform: translateY(0);
}

.fade-up.delay-1 {
  transition-delay: 0.12s;
}

.fade-up.delay-2 {
  transition-delay: 0.24s;
}

.fade-up.delay-3 {
  transition-delay: 0.36s;
}

/* --- Button Styles --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 32px;
  font-family: inherit;
  font-size: 1rem;
  font-weight: 600;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.btn-primary {
  background: var(--accent-orange);
  color: #000;
  box-shadow: 0 4px 16px rgba(255, 149, 0, 0.3);
}

.btn-primary:hover {
  background: #FFa528;
  transform: translateY(-2px);
  box-shadow: 0 6px 24px rgba(255, 149, 0, 0.4);
}

.btn-primary:active {
  transform: translateY(0);
}

.btn-lg {
  padding: 18px 44px;
  font-size: 1.125rem;
  border-radius: var(--radius-lg);
}

/* ============================================
   NAVBAR
   ============================================ */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: 16px 0;
  transition: all var(--transition-med);
  background: transparent;
}

.navbar.scrolled {
  background: rgba(13, 13, 13, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-subtle);
  padding: 12px 0;
}

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

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
}

.logo-text {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
}

.nav-links a {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

.nav-links a:hover {
  color: var(--text-primary);
}

.nav-cta {
  background: var(--accent-blue);
  color: var(--text-primary) !important;
  padding: 8px 20px;
  border-radius: var(--radius-sm);
  font-weight: 600 !important;
  transition: all var(--transition-fast) !important;
}

.nav-cta:hover {
  background: #1a8aff;
  transform: translateY(-1px);
}

/* ============================================
   HERO SECTION
   ============================================ */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  padding: 120px 0 80px;
}

/* Sound Wave Background Animation */
.hero-waves {
  position: absolute;
  inset: 0;
  overflow: hidden;
  pointer-events: none;
}

.wave {
  position: absolute;
  left: 50%;
  top: 50%;
  width: 600px;
  height: 600px;
  margin-left: -300px;
  margin-top: -300px;
  border-radius: 50%;
  border: 1px solid rgba(0, 122, 255, 0.08);
  animation: wave-pulse 6s ease-in-out infinite;
}

.wave-1 { animation-delay: 0s; }
.wave-2 { animation-delay: 1.2s; width: 500px; height: 500px; margin-left: -250px; margin-top: -250px; }
.wave-3 { animation-delay: 2.4s; width: 700px; height: 700px; margin-left: -350px; margin-top: -350px; }
.wave-4 { animation-delay: 3.6s; width: 800px; height: 800px; margin-left: -400px; margin-top: -400px; }
.wave-5 { animation-delay: 4.8s; width: 900px; height: 900px; margin-left: -450px; margin-top: -450px; }

@keyframes wave-pulse {
  0% {
    transform: scale(0.5);
    opacity: 0;
  }
  50% {
    opacity: 1;
  }
  100% {
    transform: scale(1.8);
    opacity: 0;
  }
}

.hero-content {
  text-align: center;
  position: relative;
  z-index: 2;
}

.hero-title {
  font-size: clamp(2.5rem, 7vw, 5rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: 24px;
  background: linear-gradient(135deg, var(--text-primary) 0%, var(--accent-blue) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: clamp(1.05rem, 2.5vw, 1.35rem);
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto 40px;
  line-height: 1.7;
}

/* Soundwave Visualizer */
.hero-visual {
  margin-top: 56px;
}

.soundwave-display {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 4px;
  height: 80px;
}

.soundwave-display .bar {
  width: 4px;
  height: 20px;
  background: var(--accent-blue);
  border-radius: 4px;
  animation: soundbar 1.2s ease-in-out infinite;
  opacity: 0.6;
}

.soundwave-display .bar:nth-child(1)  { animation-delay: 0.00s; height: 20px; }
.soundwave-display .bar:nth-child(2)  { animation-delay: 0.05s; height: 30px; }
.soundwave-display .bar:nth-child(3)  { animation-delay: 0.10s; height: 45px; }
.soundwave-display .bar:nth-child(4)  { animation-delay: 0.15s; height: 35px; }
.soundwave-display .bar:nth-child(5)  { animation-delay: 0.20s; height: 55px; }
.soundwave-display .bar:nth-child(6)  { animation-delay: 0.25s; height: 70px; }
.soundwave-display .bar:nth-child(7)  { animation-delay: 0.30s; height: 50px; }
.soundwave-display .bar:nth-child(8)  { animation-delay: 0.35s; height: 65px; }
.soundwave-display .bar:nth-child(9)  { animation-delay: 0.40s; height: 40px; }
.soundwave-display .bar:nth-child(10) { animation-delay: 0.45s; height: 75px; }
.soundwave-display .bar:nth-child(11) { animation-delay: 0.50s; height: 55px; }
.soundwave-display .bar:nth-child(12) { animation-delay: 0.55s; height: 80px; }
.soundwave-display .bar:nth-child(13) { animation-delay: 0.60s; height: 60px; }
.soundwave-display .bar:nth-child(14) { animation-delay: 0.65s; height: 45px; }
.soundwave-display .bar:nth-child(15) { animation-delay: 0.70s; height: 70px; }
.soundwave-display .bar:nth-child(16) { animation-delay: 0.65s; height: 50px; }
.soundwave-display .bar:nth-child(17) { animation-delay: 0.60s; height: 65px; }
.soundwave-display .bar:nth-child(18) { animation-delay: 0.55s; height: 40px; }
.soundwave-display .bar:nth-child(19) { animation-delay: 0.50s; height: 55px; }
.soundwave-display .bar:nth-child(20) { animation-delay: 0.45s; height: 75px; }
.soundwave-display .bar:nth-child(21) { animation-delay: 0.40s; height: 45px; }
.soundwave-display .bar:nth-child(22) { animation-delay: 0.35s; height: 60px; }
.soundwave-display .bar:nth-child(23) { animation-delay: 0.30s; height: 35px; }
.soundwave-display .bar:nth-child(24) { animation-delay: 0.25s; height: 50px; }
.soundwave-display .bar:nth-child(25) { animation-delay: 0.20s; height: 70px; }
.soundwave-display .bar:nth-child(26) { animation-delay: 0.15s; height: 40px; }
.soundwave-display .bar:nth-child(27) { animation-delay: 0.10s; height: 55px; }
.soundwave-display .bar:nth-child(28) { animation-delay: 0.05s; height: 30px; }
.soundwave-display .bar:nth-child(29) { animation-delay: 0.00s; height: 45px; }
.soundwave-display .bar:nth-child(30) { animation-delay: 0.05s; height: 25px; }

@keyframes soundbar {
  0%, 100% {
    transform: scaleY(0.4);
    opacity: 0.4;
  }
  50% {
    transform: scaleY(1);
    opacity: 0.8;
  }
}

/* ============================================
   SECTIONS (shared)
   ============================================ */
.section {
  padding: var(--section-padding);
}

.section-title {
  font-size: clamp(1.8rem, 4vw, 2.75rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  text-align: center;
  margin-bottom: 16px;
}

.section-subtitle {
  font-size: clamp(1rem, 2vw, 1.15rem);
  color: var(--text-secondary);
  text-align: center;
  max-width: 520px;
  margin: 0 auto 56px;
  line-height: 1.7;
}

/* ============================================
   HOW IT WORKS
   ============================================ */
.how-it-works {
  background: linear-gradient(180deg, var(--bg-primary) 0%, rgba(0, 122, 255, 0.02) 50%, var(--bg-primary) 100%);
}

.steps-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

.step-card {
  position: relative;
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-xl);
  padding: 40px 32px;
  text-align: center;
  transition: all var(--transition-med);
}

.step-card:hover {
  background: var(--bg-card-hover);
  border-color: rgba(0, 122, 255, 0.2);
  transform: translateY(-4px);
  box-shadow: var(--shadow-glow-blue);
}

.step-number {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  background: var(--accent-blue);
  color: #fff;
  font-size: 0.875rem;
  font-weight: 700;
  border-radius: 50%;
  margin-bottom: 20px;
}

.step-icon {
  margin-bottom: 20px;
}

.step-title {
  font-size: 1.35rem;
  font-weight: 700;
  margin-bottom: 12px;
  letter-spacing: -0.01em;
}

.step-desc {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.7;
  max-width: 320px;
  margin: 0 auto;
}

/* ============================================
   FEATURES
   ============================================ */
.features-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  transition: all var(--transition-med);
}

.feature-card:hover {
  background: var(--bg-card-hover);
  border-color: rgba(255, 149, 0, 0.2);
  transform: translateY(-3px);
  box-shadow: var(--shadow-glow-orange);
}

.feature-icon {
  margin-bottom: 20px;
  width: 56px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 149, 0, 0.08);
  border-radius: var(--radius-md);
}

.feature-title {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 8px;
  letter-spacing: -0.01em;
}

.feature-desc {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.7;
}

/* ============================================
   COMMUNITY
   ============================================ */
.community {
  background: linear-gradient(180deg, var(--bg-primary) 0%, rgba(0, 122, 255, 0.02) 50%, var(--bg-primary) 100%);
}

.community-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
}

.community-card {
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-lg);
  padding: 24px;
  transition: all var(--transition-med);
}

.community-card:hover {
  background: var(--bg-card-hover);
  border-color: rgba(0, 122, 255, 0.15);
  transform: translateY(-2px);
}

.community-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}

.community-avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--accent-blue);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: 700;
  color: #fff;
  flex-shrink: 0;
}

.community-name {
  display: block;
  font-weight: 600;
  font-size: 0.9rem;
}

.community-time {
  display: block;
  color: var(--text-tertiary);
  font-size: 0.8rem;
}

.community-question {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 12px;
  line-height: 1.4;
}

.community-tags {
  display: flex;
  gap: 8px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}

.tag {
  display: inline-block;
  padding: 4px 12px;
  background: rgba(0, 122, 255, 0.1);
  color: var(--accent-blue);
  font-size: 0.75rem;
  font-weight: 600;
  border-radius: 20px;
}

.community-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 16px;
  border-top: 1px solid var(--border-subtle);
}

.community-answers {
  display: flex;
  align-items: center;
  gap: 6px;
  color: var(--text-secondary);
  font-size: 0.85rem;
}

.community-solved {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent-green);
  background: rgba(48, 209, 88, 0.1);
  padding: 4px 12px;
  border-radius: 20px;
}

.community-pending {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent-orange);
  background: rgba(255, 149, 0, 0.1);
  padding: 4px 12px;
  border-radius: 20px;
}

/* ============================================
   STATS
   ============================================ */
.stats {
  padding: 60px 0;
}

.stats-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 40px;
  text-align: center;
}

.stat-item {
  position: relative;
}

.stat-number {
  font-size: clamp(2.5rem, 6vw, 3.5rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  background: linear-gradient(135deg, var(--accent-blue) 0%, var(--accent-orange) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.stat-plus {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 800;
  background: linear-gradient(135deg, var(--accent-blue) 0%, var(--accent-orange) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.stat-label {
  display: block;
  color: var(--text-secondary);
  font-size: 0.95rem;
  font-weight: 500;
  margin-top: 8px;
}

/* ============================================
   CTA SECTION
   ============================================ */
.cta-section {
  padding: 100px 0;
  background: linear-gradient(180deg, var(--bg-primary) 0%, rgba(0, 122, 255, 0.04) 50%, var(--bg-primary) 100%);
}

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

.download-buttons {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}

.store-btn {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  padding: 14px 28px;
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  min-width: 200px;
}

.store-btn:hover {
  background: var(--bg-card-hover);
  border-color: var(--accent-blue);
  transform: translateY(-2px);
  box-shadow: var(--shadow-glow-blue);
}

.store-text {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
}

.store-small {
  font-size: 0.7rem;
  color: var(--text-secondary);
  line-height: 1.2;
}

.store-large {
  font-size: 1.05rem;
  font-weight: 700;
  line-height: 1.3;
}

/* ============================================
   FOOTER
   ============================================ */
.footer {
  border-top: 1px solid var(--border-subtle);
  padding: 48px 0 32px;
}

.footer-content {
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.footer-brand .logo {
  margin-bottom: 12px;
}

.footer-tagline {
  color: var(--text-tertiary);
  font-size: 0.85rem;
}

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

.footer-links a {
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
  transition: color var(--transition-fast);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.footer-links a:hover {
  color: var(--text-primary);
}

.footer-bottom {
  padding-top: 24px;
  border-top: 1px solid var(--border-subtle);
}

.footer-bottom p {
  color: var(--text-tertiary);
  font-size: 0.8rem;
}

/* ============================================
   RESPONSIVE BREAKPOINTS
   ============================================ */

/* Tablet (640px+) */
@media (min-width: 640px) {
  .steps-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .community-grid {
    grid-template-columns: repeat(2, 1fr);
  }

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

  .download-buttons {
    flex-direction: row;
    justify-content: center;
  }
}

/* Desktop (900px+) */
@media (min-width: 900px) {
  :root {
    --section-padding: 120px 0;
  }

  .features-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
  }

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

  .step-card {
    padding: 48px 36px;
  }

  .footer-content {
    flex-direction: row;
    align-items: flex-start;
    justify-content: space-between;
  }

  .footer-links {
    gap: 32px;
  }
}

/* Large Desktop (1100px+) */
@media (min-width: 1100px) {
  .features-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

/* Small screens - hide nav links, show minimal nav */
@media (max-width: 639px) {
  .nav-links li:not(:last-child) {
    display: none;
  }

  .hero {
    padding: 100px 0 60px;
    min-height: auto;
  }

  .soundwave-display .bar {
    width: 3px;
  }

  .soundwave-display {
    gap: 3px;
  }

  .step-card {
    padding: 32px 24px;
  }

  .cta-section {
    padding: 80px 0;
  }
}

/* Reduced motion preference */
@media (prefers-reduced-motion: reduce) {
  .fade-up {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .wave {
    animation: none;
  }

  .soundwave-display .bar {
    animation: none;
  }

  .logo-icon rect {
    animation: none;
  }

  html {
    scroll-behavior: auto;
  }
}

/* Focus styles for accessibility */
a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--accent-blue);
  outline-offset: 4px;
  border-radius: 4px;
}