/* ==========================================================================
   VUA NƯỚC SẠCH - GLOBAL DESIGN SYSTEM & COMPONENT STYLES
   Clean, Pure Water Aesthetic (Ocean Blue, Teal, Pure White)
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@300;400;500;600;700;800&family=Outfit:wght@400;500;600;700;800&display=swap');

:root {
  /* Color Palette */
  --vns-primary: #0284C7;        /* Clean Ocean Blue */
  --vns-primary-dark: #0369A1;   /* Deep Blue */
  --vns-primary-light: #E0F2FE;  /* Soft Water Mist */
  --vns-accent: #0D9488;         /* Teal Pure */
  --vns-accent-light: #CCFBF1;   
  
  --vns-bg: #FFFFFF;
  --vns-bg-alt: #F8FAFC;
  --vns-bg-subtle: #F0F9FF;
  
  --vns-text: #0F172A;
  --vns-text-secondary: #475569;
  --vns-text-muted: #94A3B8;
  --vns-border: #E2E8F0;
  
  /* Typography */
  --font-heading: 'Outfit', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-body: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  
  /* Transitions & Shadows */
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-full: 9999px;
  
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 16px -2px rgba(2, 132, 199, 0.08);
  --shadow-lg: 0 12px 30px -4px rgba(2, 132, 199, 0.12);
  
  --transition-fast: 0.2s cubic-bezier(0.16, 1, 0.3, 1);
  --transition-normal: 0.35s cubic-bezier(0.16, 1, 0.3, 1);
}

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

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

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  color: var(--vns-text);
  font-weight: 700;
  line-height: 1.25;
}

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

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

/* Container */
.vns-container {
  width: 100%;
  max-width: 1280px;
  margin-left: auto;
  margin-right: auto;
  padding-left: 1.5rem;
  padding-right: 1.5rem;
}

.vns-section {
  padding-top: clamp(4rem, 8vw, 6.5rem);
  padding-bottom: clamp(4rem, 8vw, 6.5rem);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.9rem 1.8rem;
  font-size: 0.9rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition-normal);
  line-height: 1;
  border: 1px solid transparent;
}

.btn-sm {
  padding: 0.65rem 1.3rem;
  font-size: 0.82rem;
}

.btn-primary {
  background-color: var(--vns-primary);
  color: #ffffff;
  border-color: var(--vns-primary);
  box-shadow: 0 4px 14px rgba(2, 132, 199, 0.25);
}

.btn-primary:hover {
  background-color: var(--vns-primary-dark);
  border-color: var(--vns-primary-dark);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(2, 132, 199, 0.35);
}

.btn-outline {
  background-color: transparent;
  color: var(--vns-primary);
  border-color: var(--vns-primary);
}

.btn-outline:hover {
  background-color: var(--vns-primary-light);
  transform: translateY(-2px);
}

/* Badge */
.vns-badge {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--vns-primary-dark);
  background-color: var(--vns-primary-light);
  padding: 0.4rem 0.9rem;
  border-radius: var(--radius-full);
  margin-bottom: 1.2rem;
}

/* ==========================================================================
   TOP BAR & HEADER
   ========================================================================== */
.top-bar {
  background-color: #034D75;
  color: #ffffff;
  font-size: 0.8rem;
  padding: 0.5rem 0;
  font-weight: 500;
}

.top-bar-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.top-bar-right {
  display: flex;
  gap: 1.5rem;
}

@media (max-width: 768px) {
  .top-bar-right {
    display: none;
  }
}

.site-header {
  position: sticky;
  top: 0;
  left: 0;
  right: 0;
  margin: 0 auto;
  z-index: 1000;
  background-color: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--vns-border);
  transition: transform 0.3s ease;
}

.site-header.header-hidden {
  transform: translateY(-120%);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 80px;
}

.logo-text {
  font-family: var(--font-heading);
  font-weight: 800;
  font-size: 1.4rem;
  letter-spacing: -0.02em;
  color: var(--vns-primary);
}

.header-nav {
  display: flex;
  align-items: center;
  gap: 1.8rem;
}

.nav-link {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--vns-text);
  padding: 0.5rem 0;
  position: relative;
}

.nav-link:hover {
  color: var(--vns-primary);
}

.hamburger-btn {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
  color: var(--vns-text);
}

@media (max-width: 992px) {
  .header-nav, .header-actions {
    display: none;
  }
  .hamburger-btn {
    display: block;
  }
}

/* ==========================================================================
   HERO SECTION
   ========================================================================== */
.vns-hero-section {
  background: radial-gradient(circle at 90% 10%, rgba(2, 132, 199, 0.08), transparent 60%),
              linear-gradient(180deg, #F0F9FF 0%, #FFFFFF 100%);
  padding: clamp(3.5rem, 6vw, 5.5rem) 0;
}

.vns-hero-grid {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 3.5rem;
  align-items: center;
}

.vns-hero-content h1 {
  font-size: clamp(2.2rem, 3.8vw, 3.2rem);
  line-height: 1.15;
  margin-bottom: 1.2rem;
  color: #034D75;
}

.vns-hero-content p {
  font-size: 1.05rem;
  color: var(--vns-text-secondary);
  line-height: 1.65;
  margin-bottom: 2rem;
}

.vns-hero-actions {
  display: flex;
  gap: 1.2rem;
  flex-wrap: wrap;
}

.vns-hero-card {
  background: #ffffff;
  border-radius: var(--radius-lg);
  padding: 3.5rem 2.5rem;
  border: 1px solid var(--vns-border);
  box-shadow: var(--shadow-lg);
  text-align: center;
}

.vns-hero-card-icon {
  font-size: 3.5rem;
  margin-bottom: 1rem;
}

@media (max-width: 992px) {
  .vns-hero-grid {
    grid-template-columns: 1fr;
    text-align: center;
    gap: 2.5rem;
  }
  .vns-hero-actions {
    justify-content: center;
  }
}

/* ==========================================================================
   FEATURES / VALUE PROPS
   ========================================================================== */
.vns-features-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 2rem;
}

.vns-feature-card {
  background: #ffffff;
  padding: 2.2rem 1.8rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--vns-border);
  transition: var(--transition-normal);
}

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

.vns-feature-icon {
  font-size: 2.4rem;
  margin-bottom: 1.2rem;
}

.vns-feature-card h3 {
  font-size: 1.05rem;
  margin-bottom: 0.6rem;
}

.vns-feature-card p {
  font-size: 0.88rem;
  color: var(--vns-text-secondary);
  line-height: 1.5;
}

@media (max-width: 992px) {
  .vns-features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 580px) {
  .vns-features-grid {
    grid-template-columns: 1fr;
  }
}

/* ==========================================================================
   FOOTER
   ========================================================================== */
.site-footer {
  background-color: #032B42;
  color: rgba(255, 255, 255, 0.85);
  padding: 5rem 0 2rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1.2fr;
  gap: 3rem;
  margin-bottom: 4rem;
}

.footer-brand p {
  margin-top: 1rem;
  font-size: 0.9rem;
  line-height: 1.6;
  color: rgba(255, 255, 255, 0.7);
}

.footer-col-title {
  color: #ffffff;
  font-size: 1rem;
  margin-bottom: 1.4rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
}

.footer-links a {
  color: rgba(255, 255, 255, 0.75);
  font-size: 0.9rem;
}

.footer-links a:hover {
  color: #ffffff;
  padding-left: 4px;
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: 2rem;
  display: flex;
  justify-content: space-between;
  font-size: 0.82rem;
  color: rgba(255, 255, 255, 0.6);
  flex-wrap: wrap;
  gap: 1rem;
}

@media (max-width: 992px) {
  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 580px) {
  .footer-grid {
    grid-template-columns: 1fr;
  }
}

/* Mobile Off-canvas Drawer */
.mobile-nav-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 9990;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
}

.mobile-nav-overlay.active {
  opacity: 1;
  visibility: visible;
}

.mobile-nav-drawer {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  width: 280px;
  background: #ffffff;
  z-index: 9995;
  transform: translateX(-100%);
  transition: transform 0.35s cubic-bezier(0.16, 1, 0.3, 1);
  display: flex;
  flex-direction: column;
  padding: 1.5rem;
}

.mobile-nav-drawer.active {
  transform: translateX(0);
}

.mobile-nav-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
  border-bottom: 1px solid var(--vns-border);
  padding-bottom: 1rem;
}

.mobile-nav-close {
  background: none;
  border: none;
  font-size: 1.8rem;
  cursor: pointer;
}

.mobile-nav-body {
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
}

.mobile-nav-link {
  font-size: 1rem;
  font-weight: 600;
  color: var(--vns-text);
}