/* ===== ZALO SERVER - MAIN CSS ===== */
/* Foundation CSS for unified UI/UX across all pages */

/* ===== CSS CUSTOM PROPERTIES (VARIABLES) ===== */
:root {
  /* Primary Color Palette */
  --primary-color: #0066cc;
  --primary-light: #3385d6;
  --primary-dark: #004499;
  --primary-gradient: linear-gradient(135deg, #0066cc 0%, #3385d6 100%);
  
  /* Secondary Colors */
  --secondary-color: #6c757d;
  --accent-color: #28a745;
  --warning-color: #ffc107;
  --danger-color: #dc3545;
  --info-color: #17a2b8;
  
  /* Neutral Colors */
  --white: #ffffff;
  --light-gray: #f8f9fa;
  --medium-gray: #e9ecef;
  --dark-gray: #6c757d;
  --black: #212529;
  
  /* Background Colors */
  --bg-primary: #ffffff;
  --bg-secondary: #f8f9fa;
  --bg-dark: #343a40;
  --bg-gradient: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
  
  /* Text Colors */
  --text-primary: #212529;
  --text-secondary: #6c757d;
  --text-muted: #868e96;
  --text-white: #ffffff;
  
  /* Border & Shadow */
  --border-color: #dee2e6;
  --border-radius: 8px;
  --border-radius-sm: 4px;
  --border-radius-lg: 12px;
  --box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  --box-shadow-lg: 0 4px 12px rgba(0, 0, 0, 0.15);
  --box-shadow-hover: 0 4px 8px rgba(0, 0, 0, 0.2);
  
  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-xxl: 3rem;
  
  /* Typography */
  --font-family-primary: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  --font-family-mono: 'Courier New', Courier, monospace;
  --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-xxl: 1.5rem;
  --font-weight-light: 300;
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-bold: 700;
  
  /* Layout */
  --header-height: 70px;
  --sidebar-width: 250px;
  --container-max-width: 1200px;
  --content-padding: var(--spacing-lg);
  
  /* Transitions */
  --transition-fast: 0.15s ease-in-out;
  --transition-normal: 0.3s ease-in-out;
  --transition-slow: 0.5s ease-in-out;
  
  /* Z-index layers */
  --z-dropdown: 1000;
  --z-sticky: 1020;
  --z-fixed: 1030;
  --z-modal-backdrop: 1040;
  --z-modal: 1050;
  --z-popover: 1060;
  --z-tooltip: 1070;
}

/* ===== GLOBAL RESET & BASE STYLES ===== */
* {
  box-sizing: border-box;
}

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

body {
  font-family: var(--font-family-primary);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-normal);
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-secondary);
  margin: 0;
  padding: 0;
  min-height: 100vh;
}

/* ===== TYPOGRAPHY ===== */
h1, h2, h3, h4, h5, h6 {
  font-weight: var(--font-weight-bold);
  line-height: 1.2;
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.75rem; }
h4 { font-size: 1.5rem; }
h5 { font-size: 1.25rem; }
h6 { font-size: 1rem; }

p {
  margin-bottom: var(--spacing-md);
  color: var(--text-secondary);
}

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

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

/* ===== LAYOUT COMPONENTS ===== */
.main-wrapper {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.main-header {
  background: var(--bg-primary);
  border-bottom: 1px solid var(--border-color);
  box-shadow: var(--box-shadow);
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  height: var(--header-height);
}

.main-content {
  flex: 1;
  padding: var(--content-padding);
  max-width: var(--container-max-width);
  margin: 0 auto;
  width: 100%;
}

.main-footer {
  background: var(--bg-dark);
  color: var(--text-white);
  padding: var(--spacing-lg) 0;
  margin-top: auto;
}

/* ===== CARD COMPONENTS ===== */
.card-modern {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius);
  box-shadow: var(--box-shadow);
  transition: all var(--transition-normal);
  overflow: hidden;
}

.card-modern:hover {
  box-shadow: var(--box-shadow-hover);
  transform: translateY(-2px);
}

.card-modern .card-header {
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
  padding: var(--spacing-lg);
  font-weight: var(--font-weight-medium);
}

.card-modern .card-body {
  padding: var(--spacing-lg);
}

.card-modern .card-footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: var(--spacing-md) var(--spacing-lg);
}

/* ===== BUTTON ENHANCEMENTS ===== */
.btn-modern {
  border-radius: var(--border-radius);
  font-weight: var(--font-weight-medium);
  padding: var(--spacing-sm) var(--spacing-lg);
  transition: all var(--transition-fast);
  border: none;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.btn-modern:hover {
  transform: translateY(-1px);
  box-shadow: var(--box-shadow);
}

.btn-primary-modern {
  background: var(--primary-gradient);
  color: var(--text-white);
}

.btn-primary-modern:hover {
  background: var(--primary-dark);
  color: var(--text-white);
}

/* ===== FORM ENHANCEMENTS ===== */
.form-modern .form-control {
  border-radius: var(--border-radius);
  border: 1px solid var(--border-color);
  padding: var(--spacing-sm) var(--spacing-md);
  transition: all var(--transition-fast);
}

.form-modern .form-control:focus {
  border-color: var(--primary-color);
  box-shadow: 0 0 0 0.2rem rgba(0, 102, 204, 0.25);
}

.form-modern .form-label {
  font-weight: var(--font-weight-medium);
  color: var(--text-primary);
  margin-bottom: var(--spacing-sm);
}

/* ===== UTILITY CLASSES ===== */
.text-gradient {
  background: var(--primary-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.bg-gradient-primary {
  background: var(--primary-gradient);
}

.shadow-modern {
  box-shadow: var(--box-shadow-lg);
}

.rounded-modern {
  border-radius: var(--border-radius);
}

.transition-modern {
  transition: all var(--transition-normal);
}

/* ===== RESPONSIVE BREAKPOINTS ===== */
/* Mobile First Approach */
@media (max-width: 576px) {
  :root {
    --content-padding: var(--spacing-md);
    --header-height: 60px;
  }
  
  .main-content {
    padding: var(--spacing-md);
  }
  
  h1 { font-size: 2rem; }
  h2 { font-size: 1.75rem; }
  h3 { font-size: 1.5rem; }
}

@media (min-width: 768px) {
  .main-content {
    padding: var(--spacing-xl);
  }
}

@media (min-width: 992px) {
  .main-content {
    padding: var(--spacing-xxl);
  }
}

/* ===== LOADING & ANIMATION UTILITIES ===== */
.loading-spinner {
  display: inline-block;
  width: 20px;
  height: 20px;
  border: 3px solid rgba(255, 255, 255, 0.3);
  border-radius: 50%;
  border-top-color: var(--primary-color);
  animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.fade-in {
  animation: fadeIn 0.5s ease-in-out;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ===== ACCESSIBILITY ===== */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Focus styles for accessibility */
.btn:focus,
.form-control:focus,
a:focus {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
}

/* ===== LOADING OVERLAY ===== */
.loading-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.7);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: var(--z-modal);
}

.loading-content {
  text-align: center;
  color: var(--text-white);
}

.loading-text {
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-medium);
}

/* ===== DASHBOARD LAYOUT ===== */
.dashboard-layout {
  display: flex;
  min-height: 100vh;
  flex-direction: column;
}

/* Dashboard Header */
.dashboard-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  z-index: var(--z-fixed);
  box-shadow: var(--box-shadow);
}

/* Dashboard Sidebar */
.dashboard-sidebar {
  position: fixed;
  top: var(--header-height);
  left: 0;
  width: var(--sidebar-width);
  height: calc(100vh - var(--header-height));
  z-index: var(--z-sticky);
  overflow-y: auto;
  overflow-x: hidden;
  transition: transform var(--transition-normal);
}

.sidebar-content {
  padding: var(--spacing-lg) 0;
}

/* Sidebar Navigation */
.sidebar-nav .nav {
  padding: 0 var(--spacing-md);
}

.sidebar-nav .nav-item {
  margin-bottom: var(--spacing-xs);
}

.sidebar-nav .nav-link {
  display: flex;
  align-items: center;
  padding: var(--spacing-sm) var(--spacing-md);
  color: var(--text-secondary);
  text-decoration: none;
  border-radius: var(--border-radius-sm);
  transition: all var(--transition-fast);
  font-weight: var(--font-weight-normal);
  font-size: var(--font-size-sm);
}

.sidebar-nav .nav-link:hover {
  background-color: var(--bg-secondary);
  color: var(--primary-color);
  transform: translateX(2px);
}

.sidebar-nav .nav-link.active {
  background-color: var(--primary-color);
  color: var(--text-white);
  font-weight: var(--font-weight-medium);
  box-shadow: var(--box-shadow);
}

.sidebar-nav .nav-link i {
  width: 20px;
  text-align: center;
  font-size: var(--font-size-sm);
}

/* Sidebar Section Titles */
.nav-section-title {
  display: flex;
  align-items: center;
  padding: var(--spacing-md) var(--spacing-md) var(--spacing-sm);
  color: var(--text-muted);
  font-weight: var(--font-weight-medium);
  font-size: var(--font-size-xs);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.nav-section-title i {
  width: 20px;
  text-align: center;
  font-size: var(--font-size-xs);
}

/* Sidebar Dividers */
.nav-divider {
  height: 1px;
  background-color: var(--border-color);
  margin: var(--spacing-md) var(--spacing-lg);
}

/* Dashboard Main Content */
.dashboard-main {
  margin-left: var(--sidebar-width);
  margin-top: var(--header-height);
  padding: var(--content-padding);
  min-height: calc(100vh - var(--header-height));
  display: flex;
  flex-direction: column;
}

/* Standalone Layout (for admin-login) */
.standalone-wrapper {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-gradient);
}

/* Responsive Design */
@media (max-width: 991.98px) {
  .dashboard-sidebar {
    transform: translateX(-100%);
  }

  .dashboard-sidebar.show {
    transform: translateX(0);
    box-shadow: var(--box-shadow-lg);
  }

  .dashboard-main {
    margin-left: 0;
  }
}

@media (max-width: 575.98px) {
  .dashboard-main {
    padding: var(--spacing-md);
  }

  .sidebar-content {
    padding: var(--spacing-md) 0;
  }
}