/* ============================================
   Tram Thien Tra — Shared Stylesheet
   Premium Zen Design System
   ============================================ */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600&family=Playfair+Display:ital,wght@0,400;0,600;0,700;1,400&display=swap');

/* --- Custom Properties --- */
:root {
  /* Colors */
  --zen-cream: #F5EBE1; /* Lighter, warmer paper base */
  --zen-cream-dark: #E6DACD;
  --zen-brown: #463A31; /* Soft text color */
  --zen-brown-dark: #221D18; /* Deep ink wash */
  --zen-sage: #5A7D5A;
  --zen-sage-light: #8EAC8E;
  --zen-gold: #C59A63;
  --zen-white: #FFFFFF;
  
  /* Typography */
  --font-heading: 'Playfair Display', serif;
  --font-body: 'Inter', sans-serif;

  /* Structure */
  --max-width: 1080px;
  --nav-height: 72px;
  --radius: 20px;
  --radius-sm: 12px;
  
  /* Shadows & Glass */
  --shadow-sm: 0 4px 16px rgba(34, 29, 24, 0.04);
  --shadow-md: 0 10px 40px rgba(34, 29, 24, 0.08);
  --shadow-hover: 0 20px 60px rgba(34, 29, 24, 0.12);
  --glass-bg: rgba(255, 255, 255, 0.7);
  --glass-border: 1px solid rgba(255, 255, 255, 0.5);
  
  --transition: 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  --transition-slow: 0.8s cubic-bezier(0.16, 1, 0.3, 1);
}

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

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

body {
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.7;
  color: var(--zen-brown);
  background-color: var(--zen-cream);
  /* Subtle noise/paper texture */
  background-image: 
    radial-gradient(circle at 50% 0%, rgba(255,255,255,0.6) 0%, transparent 60%),
    url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noiseFilter'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.8' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noiseFilter)' opacity='0.04'/%3E%3C/svg%3E");
  background-attachment: fixed;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
}

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

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

a:hover {
  color: var(--zen-sage-light);
}

h1, h2, h3, h4 {
  font-family: var(--font-heading);
  color: var(--zen-brown-dark);
  line-height: 1.2;
  font-weight: 600;
}

h1 { font-size: 3.5rem; letter-spacing: -0.02em; margin-bottom: 0.6em; }
h2 { font-size: 2.2rem; letter-spacing: -0.01em; margin-bottom: 0.5em; }
h3 { font-size: 1.4rem; font-weight: 500; margin-bottom: 0.4em; }

p + p { margin-top: 1.2em; }
ul, ol { padding-left: 1.5em; }
li + li { margin-top: 0.4em; }

/* --- Utility & Animations --- */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

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

.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0, 0, 0, 0); border: 0;
}

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

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

.delay-100 { transition-delay: 100ms; }
.delay-200 { transition-delay: 200ms; }
.delay-300 { transition-delay: 300ms; }

/* --- Header & Navigation (Glassmorphism) --- */
.site-header {
  position: fixed;
  top: 16px;
  left: 50%;
  transform: translateX(-50%);
  width: calc(100% - 32px);
  max-width: var(--max-width);
  z-index: 100;
  background: var(--glass-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: var(--glass-border);
  border-radius: 100px;
  box-shadow: var(--shadow-sm);
  transition: padding var(--transition), box-shadow var(--transition);
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--nav-height);
  padding: 0 32px;
}

.site-logo {
  font-family: var(--font-heading);
  font-size: 1.4rem;
  color: var(--zen-brown-dark);
  font-weight: 700;
  letter-spacing: 0.02em;
  font-style: italic;
}

.site-nav {
  display: flex;
  gap: 12px;
  list-style: none;
  align-items: center;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 24px;
}

.lang-switch-btn {
  background: rgba(34, 29, 24, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.5);
  border-radius: 100px;
  padding: 4px;
  display: flex;
  align-items: center;
  cursor: pointer;
  position: relative;
  width: 68px;
  height: 32px;
  box-shadow: inset 0 2px 4px rgba(34, 29, 24, 0.05);
  transition: var(--transition);
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.lang-switch-btn .lang-text {
  flex: 1;
  text-align: center;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--zen-brown);
  opacity: 0.6;
  z-index: 2;
  transition: all var(--transition);
}

.lang-switch-slider {
  position: absolute;
  top: 4px; left: 4px;
  width: 28px; height: 24px;
  background: var(--zen-white);
  border-radius: 100px;
  box-shadow: 0 2px 8px rgba(34, 29, 24, 0.1);
  z-index: 1;
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

body.en-mode .lang-switch-slider { transform: translateX(32px); }
body.en-mode .lang-switch-btn .lang-text.en { opacity: 1; color: var(--zen-brown-dark); }
body:not(.en-mode) .lang-switch-btn .lang-text.vi { opacity: 1; color: var(--zen-brown-dark); }

/* --- Internationalization (i18n) Logic --- */
.lang-vi { display: inherit; }
.lang-en { display: none !important; }
body.en-mode .lang-vi { display: none !important; }
body.en-mode .lang-en { display: inherit !important; }

span.lang-vi, a.lang-vi, strong.lang-vi { display: inline; }
span.lang-en, a.lang-en, strong.lang-en { display: none !important; }
body.en-mode span.lang-vi, body.en-mode a.lang-vi, body.en-mode strong.lang-vi { display: none !important; }
body.en-mode span.lang-en, body.en-mode a.lang-en, body.en-mode strong.lang-en { display: inline !important; }

.site-nav a {
  display: block;
  padding: 8px 20px;
  border-radius: 100px;
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--zen-brown);
  position: relative;
  overflow: hidden;
}

.site-nav a::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0; bottom: 0;
  background: var(--zen-sage);
  border-radius: 100px;
  opacity: 0;
  transform: scale(0.8);
  transition: opacity var(--transition), transform var(--transition);
  z-index: -1;
}

.site-nav a:hover {
  color: var(--zen-sage);
}

.site-nav a.active {
  color: var(--zen-white);
}

.site-nav a.active::before {
  opacity: 1;
  transform: scale(1);
}

.menu-toggle {
  display: none;
  background: none; border: none; cursor: pointer;
  padding: 8px; color: var(--zen-brown-dark);
}

.menu-toggle span {
  display: block; width: 24px; height: 2px; background: currentColor;
  margin: 5px 0; border-radius: 2px; transition: var(--transition);
}

/* --- Main Content --- */
main {
  flex: 1;
  padding-top: 120px; /* Offset for fixed header */
}

/* --- Hero Section --- */
.hero {
  padding: 80px 0 100px;
  text-align: center;
  position: relative;
}

.hero-bg-blur {
  position: absolute;
  top: 50%; left: 50%;
  transform: translate(-50%, -50%);
  width: 600px; height: 600px;
  background: radial-gradient(circle, rgba(107, 143, 107, 0.15) 0%, rgba(212, 165, 116, 0.05) 50%, transparent 70%);
  filter: blur(60px);
  z-index: -1;
  animation: pulse 10s ease-in-out infinite alternate;
}

@keyframes pulse {
  0% { transform: translate(-50%, -50%) scale(1); opacity: 0.8; }
  100% { transform: translate(-50%, -50%) scale(1.1); opacity: 1; }
}

.hero-icon {
  width: 90px; height: 90px;
  margin: 0 auto 32px;
  display: flex; align-items: center; justify-content: center;
  animation: float 6s ease-in-out infinite;
}

@keyframes float {
  0% { transform: translateY(0px); }
  50% { transform: translateY(-10px); }
  100% { transform: translateY(0px); }
}

.hero h1 {
  background: linear-gradient(135deg, var(--zen-brown-dark) 0%, #5A4C40 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero .tagline {
  font-size: 1.25rem;
  color: var(--zen-brown);
  opacity: 0.9;
  max-width: 580px;
  margin: 0 auto 40px;
  line-height: 1.8;
  font-weight: 400;
}

/* --- Premium App Store Button --- */
.app-store-btn {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(34, 29, 24, 0.1);
  color: var(--zen-brown-dark);
  padding: 16px 36px;
  border-radius: 100px;
  font-size: 1.05rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition);
  text-decoration: none;
  box-shadow: var(--shadow-sm);
  position: relative;
  overflow: hidden;
}

.app-store-btn::after {
  content: '';
  position: absolute;
  top: 0; left: -100%; width: 100%; height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.4), transparent);
  transition: left 0.6s ease;
}

.app-store-btn:hover {
  background: var(--zen-brown-dark);
  color: var(--zen-white);
  border-color: var(--zen-brown-dark);
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

.app-store-btn:hover::after {
  left: 100%;
}

.app-store-btn svg { width: 24px; height: 24px; flex-shrink: 0; }

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

.section-title {
  text-align: center;
  margin-bottom: 64px;
  position: relative;
  font-size: 2.5rem;
}

.section-title::after {
  content: "";
  display: block;
  width: 40px;
  height: 2px;
  background: var(--zen-gold);
  margin: 20px auto 0;
  border-radius: 2px;
  opacity: 0.6;
}

/* --- Feature Cards (Glass Panels) --- */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 32px;
}

.feature-card {
  background: var(--glass-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: var(--glass-border);
  border-radius: var(--radius);
  padding: 40px 32px;
  text-align: center;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}

.feature-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; width: 100%; height: 4px;
  background: linear-gradient(90deg, transparent, var(--zen-sage), transparent);
  opacity: 0;
  transition: opacity var(--transition);
}

.feature-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-hover);
  background: rgba(255, 255, 255, 0.9);
}

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

.feature-icon {
  font-size: 2.2rem;
  margin-bottom: 24px;
  display: block;
  height: 48px;
  transition: transform var(--transition);
}

.feature-card:hover .feature-icon {
  transform: scale(1.1);
}

.feature-card h3 {
  font-size: 1.3rem;
  margin-bottom: 12px;
  color: var(--zen-brown-dark);
}

.feature-card p {
  font-size: 0.95rem;
  color: var(--zen-brown);
  opacity: 0.85;
  line-height: 1.7;
}

/* --- Philosophy Section --- */
.philosophy-section {
  text-align: center;
  padding: 80px 0;
}

.philosophy-text {
  max-width: 680px;
  margin: 0 auto 48px;
  font-size: 1.15rem;
  line-height: 1.8;
  opacity: 0.9;
}

.philosophy-pillars {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
  max-width: 800px;
  margin: 0 auto;
}

.pillar {
  text-align: center;
  padding: 32px 20px;
}

.pillar-icon {
  font-size: 2.5rem;
  display: block;
  margin-bottom: 16px;
}

.pillar h3 {
  font-size: 1.2rem;
  margin-bottom: 8px;
  color: var(--zen-brown-dark);
}

.pillar p {
  font-size: 0.95rem;
  opacity: 0.8;
}

@media (max-width: 768px) {
  .philosophy-pillars {
    grid-template-columns: 1fr;
    gap: 24px;
  }
}

/* --- Call to Action Section --- */
.cta-section {
  text-align: center;
  padding: 100px 0;
  position: relative;
}

.cta-section::before {
  content: '';
  position: absolute;
  top: 0; left: 50%; transform: translateX(-50%);
  width: 80%; height: 1px;
  background: linear-gradient(90deg, transparent, rgba(34, 29, 24, 0.1), transparent);
}

.cta-section p {
  margin-bottom: 32px;
  font-size: 1.15rem;
  opacity: 0.9;
}

/* --- Content Pages (Privacy, Support) --- */
.page-header {
  padding: 60px 0 40px;
  text-align: center;
  border-bottom: 1px solid rgba(34, 29, 24, 0.05);
}

.page-header p {
  margin-top: 12px; opacity: 0.7; font-size: 1.05rem;
}

.content-section { padding: 60px 0; }

.content-body {
  max-width: 760px;
  margin: 0 auto;
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  border: var(--glass-border);
  padding: 48px;
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
}

.content-body h2 {
  margin-top: 48px;
  padding-top: 32px;
  border-top: 1px solid rgba(34, 29, 24, 0.05);
  font-size: 1.8rem;
}

.content-body h2:first-child { margin-top: 0; padding-top: 0; border-top: none; }
.content-body h3 { margin-top: 32px; font-size: 1.3rem; color: var(--zen-sage); font-family: var(--font-body); font-weight: 600; }

.highlight-box {
  background: rgba(255, 255, 255, 0.6);
  border-left: 4px solid var(--zen-sage);
  padding: 24px 32px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: 32px 0;
  box-shadow: 0 2px 10px rgba(0,0,0,0.02);
}

.not-collect-box {
  border-left-color: var(--zen-gold);
}

/* Contact & FAQ */
.contact-card {
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  border: var(--glass-border);
  border-radius: var(--radius);
  padding: 40px;
  box-shadow: var(--shadow-sm);
  text-align: center;
  max-width: 500px;
  margin: 0 auto 60px;
}

.faq-section { max-width: 760px; margin: 0 auto; }
.faq-item {
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  border-radius: var(--radius-sm);
  margin-bottom: 16px;
  border: var(--glass-border);
  overflow: hidden;
  transition: all var(--transition);
}
.faq-item:hover { box-shadow: var(--shadow-sm); }
.faq-item[open] { background: var(--zen-white); box-shadow: var(--shadow-md); border-color: transparent; }

.faq-item summary {
  padding: 20px 48px 20px 24px;
  cursor: pointer;
  font-weight: 500;
  font-size: 1.05rem;
  color: var(--zen-brown-dark);
  position: relative;
  list-style: none;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+"; position: absolute; right: 24px; top: 50%; transform: translateY(-50%);
  font-size: 1.4rem; font-weight: 300; color: var(--zen-sage);
}
.faq-item[open] summary::after { content: "-"; }
.faq-answer { padding: 0 24px 24px; font-size: 1rem; opacity: 0.9; }

/* --- Footer --- */
.site-footer {
  background: var(--zen-brown-dark);
  color: var(--zen-cream);
  padding: 60px 0 32px;
  margin-top: auto;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.footer-content {
  display: flex; flex-wrap: wrap; justify-content: space-between;
  align-items: center; gap: 32px; margin-bottom: 40px;
}

.footer-brand {
  font-family: var(--font-heading);
  font-size: 1.5rem; font-style: italic;
  font-weight: 600; color: var(--zen-white);
  margin-bottom: 8px;
}

.footer-tagline { font-size: 0.95rem; opacity: 0.7; }
.footer-links { display: flex; gap: 24px; list-style: none; }
.footer-links a { color: var(--zen-sage-light); font-size: 0.95rem; }
.footer-links a:hover { color: var(--zen-white); }
.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: 24px; text-align: center; font-size: 0.85rem; opacity: 0.5;
}

/* --- Responsive --- */
@media (max-width: 768px) {
  h1 { font-size: 2.6rem; }
  h2 { font-size: 1.8rem; }
  
  .site-header { width: 100%; top: 0; border-radius: 0; border-top: none; border-left: none; border-right: none; }
  main { padding-top: 90px; }
  
  .menu-toggle { display: block; }
  .site-nav {
    display: none; position: absolute; top: 100%; left: 0; right: 0;
    background: rgba(255, 255, 255, 0.95); backdrop-filter: blur(20px);
    flex-direction: column; padding: 20px; align-items: stretch;
    border-bottom: 1px solid rgba(0,0,0,0.05); box-shadow: var(--shadow-md);
  }
  .header-actions { margin-top: 16px; justify-content: center; }
  .site-nav.is-open { display: flex; }
  .site-nav a { padding: 12px 20px; border-radius: var(--radius-sm); }
  
  .hero { padding: 60px 0 80px; }
  .features-grid { grid-template-columns: repeat(2, 1fr); }
  .footer-content { flex-direction: column; text-align: center; }
  .content-body { padding: 32px 24px; }
}

@media (max-width: 480px) {
  h1 { font-size: 2.2rem; }
  .hero-icon { width: 70px; height: 70px; }
  .features-grid { grid-template-columns: 1fr; }
  .app-store-btn { width: 100%; justify-content: center; }
}