/* ===================================
   CSS Variables
   =================================== */
:root {
  /* Color Scheme: Deep Ocean Teal & Velvet Purple */
  --color-primary: #1a5f7a;
  --color-primary-dark: #134252;
  --color-secondary: #57366f;
  --color-secondary-light: #7b5091;
  --color-accent: #2d8ba8;
  --color-bg: #0d1117;
  --color-bg-light: #161b22;
  --color-bg-card: #1f2937;
  --color-text: #e6edf3;
  --color-text-muted: #8b949e;
  --color-border: #30363d;
  
  /* Typography */
  --font-display: 'Georgia', 'Times New Roman', serif;
  --font-body: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  
  /* Spacing */
  --header-height: 64px;
  --container-max: 1200px;
  --spacing-xs: 8px;
  --spacing-sm: 16px;
  --spacing-md: 24px;
  --spacing-lg: 48px;
  --spacing-xl: 72px;
  
  /* Shadows */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
  
  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 16px;
}

/* ===================================
   Base Styles
   =================================== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--header-height);
}

body {
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: opacity 0.3s ease;
}

a:hover {
  opacity: 0.8;
}

a:active {
  opacity: 0.6;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

/* ===================================
   Sticky Header
   =================================== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 48px;
  background: rgba(13, 17, 23, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
  transition: background 0.3s ease;
}

.header-container {
  max-width: var(--container-max);
  margin: 0 auto;
  height: 100%;
  padding: 0 var(--spacing-sm);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

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

.header-icon {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
}

.header-title {
  font-family: var(--font-display);
  font-size: 16px;
  font-weight: 600;
  color: var(--color-text);
}

.header-nav {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.nav-link {
  display: none;
  font-size: 14px;
  color: var(--color-text-muted);
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  transition: color 0.3s ease, background 0.3s ease;
}

.nav-link:hover {
  color: var(--color-text);
  background: rgba(255, 255, 255, 0.05);
  opacity: 1;
}

.nav-cta {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 12px;
  background: var(--color-primary);
  color: var(--color-text);
  border-radius: var(--radius-md);
  font-size: 14px;
  font-weight: 500;
  transition: background 0.3s ease, transform 0.2s ease;
  min-width: 44px;
  min-height: 44px;
  justify-content: center;
}

.nav-cta:hover {
  background: var(--color-primary-dark);
  opacity: 1;
  transform: translateY(-2px);
}

.nav-cta:active {
  transform: translateY(0);
  opacity: 1;
}

.nav-cta-text {
  display: none;
}

/* ===================================
   Hero Section
   =================================== */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  padding-top: 48px;
}

.hero-banner {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.4;
}

.hero-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(180deg, 
    rgba(13, 17, 23, 0.7) 0%, 
    rgba(26, 95, 122, 0.3) 50%, 
    rgba(13, 17, 23, 0.9) 100%);
  z-index: 1;
}

.hero-container {
  position: relative;
  z-index: 2;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: var(--spacing-lg) var(--spacing-sm);
  text-align: center;
}

.hero-content {
  max-width: 600px;
  margin: 0 auto;
}

.hero-icon {
  width: 96px;
  height: 96px;
  margin: 0 auto var(--spacing-md);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
}

.hero-title {
  font-family: var(--font-display);
  font-size: 36px;
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-text);
  margin-bottom: var(--spacing-sm);
  text-shadow: 0 2px 16px rgba(0, 0, 0, 0.8);
}

.hero-subtitle {
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-lg);
  text-shadow: 0 1px 8px rgba(0, 0, 0, 0.8);
}

.hero-buttons {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
  max-width: 100%;
}

/* ===================================
   Download Buttons
   =================================== */
.download-button {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 20px;
  background: rgba(255, 255, 255, 0.05);
  border: 2px solid var(--color-primary);
  border-radius: var(--radius-md);
  color: var(--color-text);
  font-size: 14px;
  transition: all 0.3s ease;
  min-height: 56px;
  width: 100%;
  justify-content: center;
  text-align: left;
  box-shadow: 0 0 16px rgba(26, 95, 122, 0.3);
}

.download-button:hover {
  background: rgba(26, 95, 122, 0.2);
  border-color: var(--color-accent);
  transform: translateY(-2px);
  box-shadow: 0 4px 24px rgba(26, 95, 122, 0.5);
  opacity: 1;
}

.download-button:active {
  transform: translateY(0);
  opacity: 1;
}

.download-button.google-play {
  border-color: var(--color-primary);
}

.download-button.app-store {
  background: #2a2a2a;
  border-color: #4a4a4a;
  opacity: 0.55;
  filter: grayscale(0.6);
  cursor: not-allowed;
  position: relative;
}

.download-button.app-store:hover {
  background: #2a2a2a;
  border-color: #4a4a4a;
  transform: none;
  box-shadow: none;
  opacity: 0.55;
}

.button-icon {
  flex-shrink: 0;
}

.button-text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.button-label {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--color-text-muted);
}

.button-store {
  font-size: 18px;
  font-weight: 600;
  color: var(--color-text);
}

.coming-soon-badge {
  position: absolute;
  top: -8px;
  right: -8px;
  background: var(--color-secondary);
  color: var(--color-text);
  font-size: 10px;
  font-weight: 600;
  padding: 4px 8px;
  border-radius: var(--radius-sm);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  box-shadow: var(--shadow-md);
}

.download-button.large {
  min-height: 64px;
  padding: 16px 24px;
}

.download-button.large .button-icon {
  width: 28px;
  height: 28px;
}

.download-button.large .button-store {
  font-size: 20px;
}

/* ===================================
   Features Section
   =================================== */
.features {
  padding: var(--spacing-xl) var(--spacing-sm);
  background: var(--color-bg-light);
}

.features-container {
  max-width: var(--container-max);
  margin: 0 auto;
}

.section-title {
  font-family: var(--font-display);
  font-size: 32px;
  font-weight: 700;
  text-align: center;
  color: var(--color-text);
  margin-bottom: var(--spacing-sm);
}

.section-subtitle {
  font-size: 16px;
  text-align: center;
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-lg);
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.features-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--spacing-md);
  margin-top: var(--spacing-lg);
}

.feature-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--spacing-md);
  transition: transform 0.3s ease, box-shadow 0.3s ease, border-color 0.3s ease;
  position: relative;
  overflow: hidden;
}

.feature-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
  opacity: 0;
  transition: opacity 0.3s ease;
}

.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-primary);
}

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

.feature-icon {
  width: 48px;
  height: 48px;
  margin-bottom: var(--spacing-sm);
  color: var(--color-accent);
  opacity: 0.9;
}

.feature-title {
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: var(--spacing-xs);
}

.feature-description {
  font-size: 14px;
  line-height: 1.6;
  color: var(--color-text-muted);
}

/* ===================================
   Download CTA Section
   =================================== */
.download-cta {
  padding: var(--spacing-xl) var(--spacing-sm);
  background: linear-gradient(135deg, 
    var(--color-primary) 0%, 
    var(--color-secondary) 100%);
  position: relative;
  overflow: hidden;
}

.download-cta::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle, rgba(255, 255, 255, 0.1) 0%, transparent 70%);
  opacity: 0.5;
}

.download-container {
  position: relative;
  z-index: 1;
  max-width: 800px;
  margin: 0 auto;
  text-align: center;
}

.download-title {
  font-family: var(--font-display);
  font-size: 32px;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: var(--spacing-sm);
  text-shadow: 0 2px 8px rgba(0, 0, 0, 0.5);
}

.download-subtitle {
  font-size: 18px;
  color: rgba(255, 255, 255, 0.9);
  margin-bottom: var(--spacing-lg);
  text-shadow: 0 1px 4px rgba(0, 0, 0, 0.5);
}

.download-buttons {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
  max-width: 100%;
  margin: 0 auto;
}

/* ===================================
   About Section
   =================================== */
.about {
  padding: var(--spacing-xl) var(--spacing-sm);
  background: var(--color-bg);
}

.about-container {
  max-width: 800px;
  margin: 0 auto;
}

.about-text {
  font-size: 16px;
  line-height: 1.8;
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-lg);
  text-align: justify;
}

.contact-info {
  text-align: center;
  padding: var(--spacing-md);
  background: var(--color-bg-card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
}

.contact-label {
  font-size: 14px;
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-xs);
}

.contact-email {
  font-size: 18px;
  font-weight: 600;
  color: var(--color-accent);
  display: inline-block;
}

/* ===================================
   Footer
   =================================== */
.site-footer {
  padding: var(--spacing-lg) var(--spacing-sm);
  background: var(--color-bg-light);
  border-top: 1px solid var(--color-border);
}

.footer-container {
  max-width: var(--container-max);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  align-items: center;
  text-align: center;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.footer-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
}

.footer-title {
  font-family: var(--font-display);
  font-size: 16px;
  font-weight: 600;
  color: var(--color-text);
}

.footer-contact {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
  font-size: 14px;
  color: var(--color-text-muted);
}

.footer-nav {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-size: 14px;
}

.footer-link {
  color: var(--color-text-muted);
  transition: color 0.3s ease;
}

.footer-link:hover {
  color: var(--color-accent);
  opacity: 1;
}

.footer-separator {
  color: var(--color-border);
}

/* ===================================
   Mobile Sticky CTA
   =================================== */
.mobile-sticky-cta {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  padding: var(--spacing-sm);
  background: rgba(13, 17, 23, 0.95);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-top: 1px solid var(--color-border);
  z-index: 999;
  opacity: 0;
  transform: translateY(100%);
  transition: opacity 0.3s ease, transform 0.3s ease;
  padding-bottom: max(var(--spacing-sm), env(safe-area-inset-bottom));
}

.mobile-sticky-cta.visible {
  opacity: 1;
  transform: translateY(0);
}

.sticky-button {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  padding: 16px;
  background: var(--color-primary);
  color: var(--color-text);
  border-radius: var(--radius-md);
  font-size: 16px;
  font-weight: 600;
  min-height: 56px;
  transition: background 0.3s ease, transform 0.2s ease;
  box-shadow: var(--shadow-md);
}

.sticky-button:hover {
  background: var(--color-accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  opacity: 1;
}

.sticky-button:active {
  transform: translateY(0);
  opacity: 1;
}

/* ===================================
   Responsive Design - Tablet
   =================================== */
@media (min-width: 768px) {
  :root {
    --header-height: 64px;
  }
  
  .site-header {
    height: 64px;
  }
  
  .header-icon {
    width: 40px;
    height: 40px;
  }
  
  .header-title {
    font-size: 18px;
  }
  
  .nav-link {
    display: block;
  }
  
  .nav-cta {
    padding: 10px 20px;
  }
  
  .nav-cta-text {
    display: inline;
  }
  
  .hero {
    padding-top: 64px;
  }
  
  .hero-title {
    font-size: 52px;
  }
  
  .hero-subtitle {
    font-size: 18px;
  }
  
  .hero-buttons {
    flex-direction: row;
    justify-content: center;
    max-width: 560px;
    margin: 0 auto;
  }
  
  .download-button {
    width: auto;
    min-width: 200px;
  }
  
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-lg);
  }
  
  .section-title {
    font-size: 42px;
  }
  
  .section-subtitle {
    font-size: 18px;
  }
  
  .download-title {
    font-size: 42px;
  }
  
  .download-subtitle {
    font-size: 20px;
  }
  
  .download-buttons {
    flex-direction: row;
    justify-content: center;
    max-width: 560px;
  }
  
  .footer-container {
    flex-direction: row;
    justify-content: space-between;
    text-align: left;
  }
  
  .footer-contact {
    align-items: flex-start;
  }
  
  /* Hide mobile sticky CTA on tablet+ */
  .mobile-sticky-cta {
    display: none;
  }
}

/* ===================================
   Responsive Design - Desktop
   =================================== */
@media (min-width: 1024px) {
  .hero-container {
    padding: var(--spacing-xl) var(--spacing-sm);
  }
  
  .hero-icon {
    width: 120px;
    height: 120px;
  }
  
  .hero-title {
    font-size: 64px;
  }
  
  .hero-subtitle {
    font-size: 20px;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
  }
  
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .feature-card {
    padding: var(--spacing-lg);
  }
  
  .feature-icon {
    width: 56px;
    height: 56px;
  }
  
  .feature-title {
    font-size: 22px;
  }
  
  .feature-description {
    font-size: 15px;
  }
  
  .about-text {
    font-size: 17px;
  }
}