/* ============================================
   VT Group - Main Stylesheet
   Modern, Responsive Design with Light/Dark Mode
   ============================================ */

/* === CSS VARIABLES === */
:root {
  /* Light Mode Colors */
  --color-primary: #0A2540;
  --color-primary-light: #1E3A5F;
  --color-primary-dark: #051220;
  --color-accent: #00A8E8;
  --color-accent-light: #33BFEF;
  --color-accent-dark: #0088BB;
  --color-bg: #FFFFFF;
  --color-surface: #F8F9FA;
  --color-surface-hover: #F1F3F5;
  --color-text-primary: #1A1A1A;
  --color-text-secondary: #6B7280;
  --color-text-muted: #9CA3AF;
  --color-border: #E5E7EB;
  --color-success: #10B981;
  --color-warning: #F59E0B;
  --color-error: #EF4444;
  --color-info: #3B82F6;

  /* Spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  --spacing-2xl: 4rem;
  --spacing-3xl: 6rem;

  /* Typography */
  --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 2rem;
  --font-size-4xl: 2.5rem;
  --font-size-5xl: 3rem;

  /* Line Heights */
  --line-height-tight: 1.25;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;

  /* Font Weights */
  --font-weight-light: 300;
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  --font-weight-extrabold: 800;

  /* Shadows */
  --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
  --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);

  /* Border Radius */
  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
  --radius-full: 9999px;

  /* Transitions */
  --transition-fast: 150ms ease-in-out;
  --transition-base: 250ms ease-in-out;
  --transition-slow: 350ms ease-in-out;

  /* Container */
  --container-max: 1200px;
  --container-padding: 1.5rem;

  /* Header */
  --header-height: 70px;
}

/* Dark Mode Variables */
[data-theme="dark"] {
  --color-primary: #1E40AF;
  --color-primary-light: #3B82F6;
  --color-primary-dark: #1E3A8A;
  --color-accent: #06B6D4;
  --color-accent-light: #22D3EE;
  --color-accent-dark: #0891B2;
  --color-bg: #0F172A;
  --color-surface: #1E293B;
  --color-surface-hover: #334155;
  --color-text-primary: #F1F5F9;
  --color-text-secondary: #94A3B8;
  --color-text-muted: #64748B;
  --color-border: #334155;
  --color-success: #34D399;
  --color-warning: #FBBF24;
  --color-error: #F87171;
  --color-info: #60A5FA;

  /* Darker shadows for dark mode */
  --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.4), 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.5), 0 2px 4px -1px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.6), 0 4px 6px -2px rgba(0, 0, 0, 0.4);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.7), 0 10px 10px -5px rgba(0, 0, 0, 0.5);
  --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.8);
}

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

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

body {
  font-family: var(--font-primary);
  font-size: var(--font-size-base);
  line-height: var(--line-height-normal);
  color: var(--color-text-primary);
  background-color: var(--color-bg);
  transition: background-color var(--transition-base), color var(--transition-base);
  -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: color var(--transition-fast);
}

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

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

ul, ol {
  list-style: none;
}

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

/* === HEADER === */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-base);
  height: var(--header-height);
}

.header-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
}

/* Logo */
.logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: var(--font-size-xl);
  font-weight: var(--font-weight-bold);
  color: var(--color-primary);
  transition: color var(--transition-fast);
}

.logo:hover {
  color: var(--color-accent);
}

.logo svg {
  color: var(--color-primary);
  transition: color var(--transition-fast);
}

.logo:hover svg {
  color: var(--color-accent);
}

/* Main Navigation */
.main-nav {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

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

.nav-list a {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.5rem 1rem;
  color: var(--color-text-primary);
  font-weight: var(--font-weight-medium);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
}

.nav-list a:hover {
  color: var(--color-accent);
  background-color: var(--color-surface);
}

.nav-list a.active {
  color: var(--color-accent);
  background-color: var(--color-surface);
}

/* Dropdown */
.nav-dropdown {
  position: relative;
}

.dropdown-icon {
  transition: transform var(--transition-fast);
}

.nav-dropdown:hover .dropdown-icon {
  transform: rotate(180deg);
}

.dropdown-menu {
  position: absolute;
  top: 100%;
  left: 0;
  margin-top: 0.5rem;
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  min-width: 200px;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-10px);
  transition: all var(--transition-base);
}

.nav-dropdown:hover .dropdown-menu {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.dropdown-menu li a {
  display: block;
  padding: 0.75rem 1rem;
  border-radius: 0;
}

.dropdown-menu li:first-child a {
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
}

.dropdown-menu li:last-child a {
  border-radius: 0 0 var(--radius-lg) var(--radius-lg);
}

/* Theme Toggle */
.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  background-color: var(--color-surface);
  color: var(--color-text-primary);
  transition: all var(--transition-fast);
  margin-left: var(--spacing-sm);
}

.theme-toggle:hover {
  background-color: var(--color-surface-hover);
  transform: scale(1.05);
}

.theme-toggle svg {
  width: 20px;
  height: 20px;
}

.sun-icon {
  display: none;
}

.moon-icon {
  display: block;
}

[data-theme="dark"] .sun-icon {
  display: block;
}

[data-theme="dark"] .moon-icon {
  display: none;
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  gap: 0.375rem;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  background-color: var(--color-surface);
  transition: background-color var(--transition-fast);
}

.mobile-menu-toggle:hover {
  background-color: var(--color-surface-hover);
}

.mobile-menu-toggle span {
  display: block;
  width: 20px;
  height: 2px;
  background-color: var(--color-text-primary);
  transition: all var(--transition-fast);
}

.mobile-menu-toggle.active span:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}

.mobile-menu-toggle.active span:nth-child(2) {
  opacity: 0;
}

.mobile-menu-toggle.active span:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

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

/* === SECTIONS === */
section {
  padding: var(--spacing-3xl) 0;
}

section:nth-child(even) {
  background-color: var(--color-surface);
}

.section-title {
  font-size: var(--font-size-3xl);
  font-weight: var(--font-weight-bold);
  text-align: center;
  margin-bottom: var(--spacing-xl);
  color: var(--color-primary);
}

.section-subtitle {
  font-size: var(--font-size-lg);
  text-align: center;
  color: var(--color-text-secondary);
  max-width: 700px;
  margin: 0 auto var(--spacing-xl);
}

/* === HERO SECTION === */
.hero {
  position: relative;
  min-height: calc(100vh - var(--header-height));
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
  color: white;
  padding: var(--spacing-3xl) 0;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image: url('../img/hero-bg.jpg');
  background-size: cover;
  background-position: center;
  opacity: 0.1;
  z-index: 0;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 900px;
}

.hero h1 {
  font-size: var(--font-size-5xl);
  font-weight: var(--font-weight-extrabold);
  margin-bottom: var(--spacing-md);
  line-height: var(--line-height-tight);
}

.hero p {
  font-size: var(--font-size-xl);
  margin-bottom: var(--spacing-xl);
  color: rgba(255, 255, 255, 0.9);
}

.hero-buttons {
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
  flex-wrap: wrap;
}

/* === BUTTONS === */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.875rem 2rem;
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-semibold);
  border-radius: var(--radius-lg);
  transition: all var(--transition-fast);
  cursor: pointer;
  border: 2px solid transparent;
  text-align: center;
}

.btn-primary {
  background-color: var(--color-accent);
  color: white;
}

.btn-primary:hover {
  background-color: var(--color-accent-dark);
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.btn-secondary {
  background-color: transparent;
  color: white;
  border-color: white;
}

.btn-secondary:hover {
  background-color: white;
  color: var(--color-primary);
}

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

.btn-outline:hover {
  background-color: var(--color-accent);
  color: white;
}

.btn-large {
  padding: 1.125rem 2.5rem;
  font-size: var(--font-size-lg);
}

/* === CARDS === */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: var(--spacing-lg);
}

.card {
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--spacing-xl);
  transition: all var(--transition-base);
}

.card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-xl);
  border-color: var(--color-accent);
}

.card-icon {
  width: 60px;
  height: 60px;
  background: linear-gradient(135deg, var(--color-accent), var(--color-accent-light));
  border-radius: var(--radius-xl);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--spacing-md);
  color: white;
  font-size: var(--font-size-2xl);
  font-weight: var(--font-weight-bold);
}

.card h3 {
  font-size: var(--font-size-xl);
  font-weight: var(--font-weight-bold);
  margin-bottom: var(--spacing-sm);
  color: var(--color-primary);
}

.card p {
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-md);
  line-height: var(--line-height-relaxed);
}

/* === TESTIMONIALS === */
.testimonials {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-lg);
}

.testimonial {
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--spacing-xl);
  position: relative;
}

.testimonial::before {
  content: '"';
  position: absolute;
  top: var(--spacing-md);
  left: var(--spacing-md);
  font-size: 4rem;
  color: var(--color-accent);
  opacity: 0.2;
  font-family: Georgia, serif;
  line-height: 1;
}

.testimonial-text {
  font-style: italic;
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-md);
  line-height: var(--line-height-relaxed);
}

.testimonial-author {
  font-weight: var(--font-weight-semibold);
  color: var(--color-primary);
}

.testimonial-company {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
}

/* === CTA SECTION === */
.cta-section {
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-light));
  color: white;
  text-align: center;
  padding: var(--spacing-3xl) 0;
}

.cta-section h2 {
  font-size: var(--font-size-3xl);
  margin-bottom: var(--spacing-md);
}

.cta-section p {
  font-size: var(--font-size-lg);
  margin-bottom: var(--spacing-xl);
  opacity: 0.9;
}

/* === FOOTER === */
.site-footer {
  background-color: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding: var(--spacing-3xl) 0 var(--spacing-lg);
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-xl);
  margin-bottom: var(--spacing-xl);
}

.footer-column h3 {
  margin-bottom: var(--spacing-md);
  color: var(--color-primary);
  font-weight: var(--font-weight-bold);
}

.footer-logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: var(--font-size-xl);
  font-weight: var(--font-weight-bold);
  color: var(--color-primary);
  margin-bottom: var(--spacing-md);
}

.footer-about {
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
  margin-bottom: var(--spacing-md);
}

.footer-social {
  display: flex;
  gap: var(--spacing-sm);
}

.footer-social a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  background-color: var(--color-surface-hover);
  color: var(--color-text-primary);
  transition: all var(--transition-fast);
}

.footer-social a:hover {
  background-color: var(--color-accent);
  color: white;
  transform: translateY(-3px);
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.footer-links a {
  color: var(--color-text-secondary);
  transition: color var(--transition-fast);
}

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

.footer-contact {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.footer-contact li {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  color: var(--color-text-secondary);
}

.footer-contact svg {
  flex-shrink: 0;
  margin-top: 0.125rem;
}

.footer-contact a {
  color: var(--color-text-secondary);
}

.footer-contact a:hover {
  color: var(--color-accent);
}

.footer-hours {
  margin-top: var(--spacing-md);
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
  line-height: var(--line-height-relaxed);
}

.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: var(--spacing-lg);
  border-top: 1px solid var(--color-border);
  flex-wrap: wrap;
  gap: var(--spacing-md);
}

.footer-bottom p {
  color: var(--color-text-muted);
  font-size: var(--font-size-sm);
}

.footer-bottom-links {
  display: flex;
  gap: var(--spacing-md);
}

.footer-bottom-links a {
  color: var(--color-text-muted);
  font-size: var(--font-size-sm);
}

.footer-bottom-links a:hover {
  color: var(--color-accent);
}

/* === FORMS === */
.form-group {
  margin-bottom: var(--spacing-md);
}

.form-label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: var(--font-weight-medium);
  color: var(--color-text-primary);
}

.form-input,
.form-textarea,
.form-select {
  width: 100%;
  padding: 0.875rem 1rem;
  font-size: var(--font-size-base);
  font-family: inherit;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  background-color: var(--color-bg);
  color: var(--color-text-primary);
  transition: all var(--transition-fast);
}

.form-input:focus,
.form-textarea:focus,
.form-select:focus {
  outline: none;
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px rgba(0, 168, 232, 0.1);
}

.form-textarea {
  resize: vertical;
  min-height: 150px;
}

.form-error {
  color: var(--color-error);
  font-size: var(--font-size-sm);
  margin-top: 0.25rem;
}

/* === FLASH MESSAGES === */
.flash-message {
  position: fixed;
  top: calc(var(--header-height) + 1rem);
  right: 1rem;
  max-width: 400px;
  padding: 1rem 1.5rem;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-xl);
  z-index: 9999;
  animation: slideIn 0.3s ease-out;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

@keyframes slideIn {
  from {
    transform: translateX(400px);
    opacity: 0;
  }
  to {
    transform: translateX(0);
    opacity: 1;
  }
}

.flash-success {
  background-color: var(--color-success);
  color: white;
}

.flash-error {
  background-color: var(--color-error);
  color: white;
}

.flash-warning {
  background-color: var(--color-warning);
  color: white;
}

.flash-info {
  background-color: var(--color-info);
  color: white;
}

.flash-close {
  background: none;
  border: none;
  color: white;
  font-size: 1.5rem;
  cursor: pointer;
  padding: 0;
  line-height: 1;
  opacity: 0.8;
  transition: opacity var(--transition-fast);
}

.flash-close:hover {
  opacity: 1;
}

/* === RESPONSIVE === */
@media (max-width: 768px) {
  :root {
    --font-size-3xl: 1.75rem;
    --font-size-4xl: 2rem;
    --font-size-5xl: 2.25rem;
    --spacing-3xl: 3rem;
    --container-padding: 1rem;
  }

  .mobile-menu-toggle {
    display: flex;
  }

  .main-nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-lg);
    padding: var(--spacing-md);
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-base);
  }

  .main-nav.active {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    width: 100%;
  }

  .dropdown-menu {
    position: static;
    opacity: 1;
    visibility: visible;
    transform: none;
    margin-top: 0.5rem;
    box-shadow: none;
    border: none;
    background-color: var(--color-surface);
  }

  .hero h1 {
    font-size: var(--font-size-4xl);
  }

  .hero-buttons {
    flex-direction: column;
  }

  .cards-grid {
    grid-template-columns: 1fr;
  }

  .footer-bottom {
    flex-direction: column;
    text-align: center;
  }

  .flash-message {
    right: 1rem;
    left: 1rem;
    max-width: none;
  }
}

@media (max-width: 480px) {
  .hero h1 {
    font-size: var(--font-size-3xl);
  }

  .btn {
    width: 100%;
  }
}