/* =================================================================
   Modern Responsive CSS for Ho Chi Minh City Website
   Vietnam-inspired design with mobile-first approach
   Based on Vietnam flag colors (red #DA020E, yellow #FFCD00)
   ================================================================= */

/* ===== CSS VARIABLES - Vietnam Flag Colors ===== */
:root {
  /* Vietnam Flag Colors */
  --vietnam-red: #DA020E;
  --vietnam-yellow: #FFCD00;
  --vietnam-red-dark: #B8010C;
  --vietnam-red-light: #E53E4A;
  
  /* Extended Palette */
  --primary-red: var(--vietnam-red);
  --accent-yellow: var(--vietnam-yellow);
  --text-dark: #2C3E50;
  --text-light: #6C757D;
  --white: #FFFFFF;
  --background-light: #F8F9FA;
  --border-light: #E9ECEF;
  --hero-overlay: rgba(218, 2, 14, 0.15);
  
  /* Typography */
  --font-primary: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  --font-secondary: Georgia, 'Times New Roman', serif;
  
  /* Spacing */
  --container-max-width: 1200px;
  --mobile-padding: 1.5rem;
  --section-padding: 2rem 0;
  --border-radius: 8px;
  
  /* Shadows */
  --shadow-light: 0 2px 4px rgba(0,0,0,0.1);
  --shadow-medium: 0 4px 8px rgba(0,0,0,0.15);
  --shadow-strong: 0 8px 16px rgba(0,0,0,0.2);
}

/* ===== RESET & BASE STYLES ===== */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  font-family: var(--font-primary);
  line-height: 1.6;
  color: var(--text-dark);
  background-color: var(--background-light);
}

/* ===== LAYOUT CONTAINERS ===== */
.container {
  max-width: var(--container-max-width);
  margin: 0 auto;
  padding: 0 var(--mobile-padding);
}

.content-wrapper {
  padding: var(--mobile-padding);
}

/* ===== HEADER & HERO SECTION ===== */
.site-header {
  position: relative;
  background: linear-gradient(var(--hero-overlay), var(--hero-overlay)), 
              url('images/Content_Images/7147506961_84391ae836_z.jpg') center/cover;
  min-height: 400px;
  display: flex;
  align-items: center;
  color: var(--white);
}

.hero-content {
  text-align: center;
  z-index: 2;
  width: 100%;
}

.hero-title {
  font-size: 2.5rem;
  font-weight: bold;
  margin-bottom: 1rem;
  text-shadow: 2px 2px 4px rgba(0,0,0,0.7);
  background: rgba(0,0,0,0.3);
  padding: 1rem 2rem;
  border-radius: var(--border-radius);
  display: inline-block;
}

.hero-subtitle {
  font-size: 1.2rem;
  margin-bottom: 2rem;
  text-shadow: 1px 1px 2px rgba(0,0,0,0.7);
  background: rgba(0,0,0,0.2);
  padding: 0.5rem 1rem;
  border-radius: var(--border-radius);
  display: inline-block;
}

/* ===== NAVIGATION ===== */
.main-navigation {
  background: var(--white);
  box-shadow: var(--shadow-medium);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem var(--mobile-padding);
  position: relative;
}

.site-logo {
  font-size: 1.5rem;
  font-weight: bold;
  color: var(--primary-red);
  text-decoration: none;
}

.nav-menu {
  display: none;
  list-style: none;
  gap: 2rem;
}

.nav-menu a {
  color: var(--text-dark);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.3s ease;
}

.nav-menu a:hover {
  color: var(--primary-red);
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
  display: block;
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--text-dark);
  cursor: pointer;
  padding: 1rem;
  border-radius: var(--border-radius);
  transition: all 0.3s ease;
  position: absolute;
  top: 1rem;
  right: 1rem;
  z-index: 10001;
}

.mobile-menu-toggle:hover {
  background-color: var(--background-light);
  color: var(--primary-red);
}

/* Mobile Menu Overlay */
.mobile-menu-overlay {
  position: fixed;
  top: 0;
  left: -280px;
  width: 280px;
  height: 100vh;
  background: var(--white);
  box-shadow: var(--shadow-strong);
  z-index: 9999;
  transition: left 0.3s ease;
  overflow-y: auto;
  transform: translateX(0); /* Ensure transform is reset */
}

.mobile-menu-overlay.active {
  left: 0 !important;
  transform: translateX(0);
}

/* Ensure mobile menu is hidden by default */
@media (min-width: 768px) {
  .mobile-menu-overlay {
    display: none;
  }
}

.mobile-menu-header {
  padding: 1.5rem;
  background: var(--primary-red);
  color: var(--white);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.mobile-menu-close {
  background: none;
  border: none;
  color: var(--white);
  font-size: 1.5rem;
  cursor: pointer;
  padding: 0.5rem;
}

.mobile-nav-menu {
  list-style: none;
  padding: 0;
  margin: 0;
}

.mobile-nav-menu li {
  border-bottom: 1px solid var(--border-light);
}

.mobile-nav-menu a {
  display: block;
  padding: 1rem 1.5rem;
  color: var(--text-dark);
  text-decoration: none;
  transition: background-color 0.3s ease;
}

.mobile-nav-menu a:hover {
  background-color: var(--background-light);
  color: var(--primary-red);
}

/* Mobile Menu Backdrop */
.mobile-menu-backdrop {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.5);
  z-index: 9998;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
}

.mobile-menu-backdrop.active {
  opacity: 1;
  visibility: visible;
}

/* Body scroll lock when menu is open */
body.mobile-menu-open {
  overflow: hidden;
}

/* ===== MAIN CONTENT ===== */
.main-content {
  min-height: calc(100vh - 200px);
}

.page-content {
  background: var(--white);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-light);
  margin: 2rem 0;
  overflow: hidden;
}

.content-header {
  padding: 2rem var(--mobile-padding);
  background: linear-gradient(135deg, var(--primary-red), var(--vietnam-red-dark));
  color: var(--white);
}

.page-title {
  font-size: 2rem;
  margin-bottom: 0.5rem;
}

.page-subtitle {
  font-size: 1.1rem;
  opacity: 0.9;
}

.content-body {
  padding: 2rem var(--mobile-padding);
}

/* ===== CALLOUT STYLES ===== */
.callout-info {
  background: linear-gradient(135deg, #E3F2FD, #BBDEFB);
  border: 1px solid #90CAF9;
  border-radius: var(--border-radius);
  padding: 1.5rem;
  margin: 1.5rem 0;
  box-shadow: var(--shadow-light);
}

.callout-warning {
  background: linear-gradient(135deg, #FFF3E0, #FFE0B2);
  border: 1px solid #FFCC02;
  border-radius: var(--border-radius);
  padding: 1.5rem;
  margin: 1.5rem 0;
  box-shadow: var(--shadow-light);
}

.callout-tip {
  background: linear-gradient(135deg, #E8F5E8, #C8E6C9);
  border: 1px solid #81C784;
  border-radius: var(--border-radius);
  padding: 1.5rem;
  margin: 1.5rem 0;
  box-shadow: var(--shadow-light);
}

.callout-fact {
  background: linear-gradient(135deg, #FCE4EC, #F8BBD9);
  border: 1px solid #F06292;
  border-radius: var(--border-radius);
  padding: 1.5rem;
  margin: 1.5rem 0;
  box-shadow: var(--shadow-light);
}

.callout-cultural {
  background: linear-gradient(135deg, #FFF8E1, #FFECB3);
  border: 1px solid var(--accent-yellow);
  border-radius: var(--border-radius);
  padding: 1.5rem;
  margin: 1.5rem 0;
  box-shadow: var(--shadow-light);
}

/* Callout Typography */
.callout-info h3,
.callout-warning h3,
.callout-tip h3,
.callout-fact h3,
.callout-cultural h3 {
  margin-bottom: 1rem;
  font-size: 1.2rem;
  color: var(--text-dark);
}

/* ===== TYPOGRAPHY ===== */
h1, h2, h3, h4, h5, h6 {
  color: var(--text-dark);
  margin-bottom: 1rem;
  line-height: 1.3;
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }
h5 { font-size: 1.1rem; }
h6 { font-size: 1rem; }

p {
  margin-bottom: 1rem;
  line-height: 1.7;
}

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

a:hover {
  color: var(--vietnam-red-dark);
  text-decoration: underline;
}

/* ===== IMAGES ===== */
img {
  max-width: 100%;
  height: auto;
  border-radius: var(--border-radius);
}

/* Mobile image full-width */
@media (max-width: 768px) {
  .full-width-mobile {
    margin-left: calc(-1 * var(--mobile-padding));
    margin-right: calc(-1 * var(--mobile-padding));
    border-radius: 0;
  }
}

/* ===== FOOTER ===== */
.site-footer {
  background: var(--text-dark);
  color: var(--white);
  padding: 3rem 0 2rem;
  margin-top: 4rem;
}

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

.footer-links {
  list-style: none;
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-bottom: 2rem;
  flex-wrap: wrap;
}

.footer-links a {
  color: var(--white);
  opacity: 0.8;
  transition: opacity 0.3s ease;
}

.footer-links a:hover {
  opacity: 1;
}

.copyright {
  opacity: 0.7;
  font-size: 0.9rem;
}

/* ===== RESPONSIVE DESIGN ===== */

/* Tablet */
@media (min-width: 768px) {
  :root {
    --mobile-padding: 2rem;
  }
  
  .hero-title {
    font-size: 3.5rem;
  }
  
  .hero-subtitle {
    font-size: 1.4rem;
  }
  
  .content-wrapper {
    padding: 2rem;
  }
  
  .mobile-menu-toggle {
    display: none;
  }
  
  .nav-menu {
    display: flex;
  }
}

/* Desktop */
@media (min-width: 1024px) {
  :root {
    --mobile-padding: 3rem;
  }
  
  .hero-title {
    font-size: 4rem;
  }
  
  .site-header {
    min-height: 500px;
  }
  
  .content-wrapper {
    padding: 3rem;
  }
}

/* Large Desktop */
@media (min-width: 1200px) {
  .container {
    padding: 0 2rem;
  }
}

/* ===== UTILITY CLASSES ===== */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mb-1 { margin-bottom: 1rem; }
.mb-2 { margin-bottom: 2rem; }
.mb-3 { margin-bottom: 3rem; }

.mt-1 { margin-top: 1rem; }
.mt-2 { margin-top: 2rem; }
.mt-3 { margin-top: 3rem; }

.hidden { display: none; }
.visible { display: block; }

/* ===== ACCESSIBILITY ===== */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Focus styles for accessibility */
:focus {
  outline: 2px solid var(--primary-red);
  outline-offset: 2px;
}

/* Skip link for screen readers */
.skip-link {
  position: absolute;
  top: -40px;
  left: 6px;
  background: var(--primary-red);
  color: var(--white);
  padding: 8px;
  text-decoration: none;
  z-index: 10000;
}

.skip-link:focus {
  top: 6px;
}