/* ============================================
   MODERN UI/UX - IVS Learning Hub
   Mobile-First, Minimalist Design System
   ============================================ */

/* ========== CSS VARIABLES (Design Tokens) ========== */
:root {
  /* Colors - Primary Palette */
  --color-primary: #4c5ef7;
  --color-primary-light: #5d6eff;
  --color-primary-dark: #3b4fd6;
  --color-secondary: #22d3ee;
  --color-success: #10b981;
  --color-warning: #f97316;
  --color-error: #ef4444;
  
  /* Neutral Colors */
  --color-bg: #0f0f0f;
  --color-bg-secondary: #1a1a1a;
  --color-bg-tertiary: #262626;
  --color-border: #27272a;
  --color-text: #f5f5f5;
  --color-text-secondary: #a8a8a8;
  
  /* Spacing (8px Grid System) */
  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;
  --spacing-2xl: 40px;
  --spacing-3xl: 48px;
  
  /* Typography */
  --font-primary: 'Be Vietnam Pro', sans-serif;
  --font-secondary: 'Inter', sans-serif;
  --font-mono: 'Fira Code', monospace;
  
  --font-size-xs: 12px;
  --font-size-sm: 14px;
  --font-size-base: 16px;
  --font-size-lg: 18px;
  --font-size-xl: 20px;
  --font-size-2xl: 24px;
  --font-size-3xl: 28px;
  --font-size-4xl: 36px;
  --font-size-5xl: 48px;
  
  --line-height-tight: 1.4;
  --line-height-normal: 1.6;
  --line-height-relaxed: 1.8;
  
  /* Shadows */
  --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.15);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.3);
  --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.5);
  
  /* Border Radius */
  --radius-xs: 4px;
  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-2xl: 20px;
  --radius-full: 9999px;
  
  /* Transitions */
  --transition-fast: 0.15s ease-in-out;
  --transition-normal: 0.3s ease-in-out;
  --transition-slow: 0.5s ease-in-out;
}

/* ========== GLOBAL RESET ========== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  background-color: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-primary);
  font-size: var(--font-size-base);
  line-height: var(--line-height-normal);
  overflow-x: hidden;
}

/* ========== TYPOGRAPHY ========== */

h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: var(--line-height-tight);
  margin-bottom: var(--spacing-md);
}

h1 {
  font-size: var(--font-size-3xl);
  letter-spacing: -0.5px;
}

h2 {
  font-size: var(--font-size-2xl);
  letter-spacing: -0.25px;
}

h3 {
  font-size: var(--font-size-xl);
}

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

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

a:hover {
  color: #06b6d4;
}

/* Media queries for typography scaling */
@media (min-width: 768px) {
  h1 { font-size: var(--font-size-4xl); }
  h2 { font-size: var(--font-size-3xl); }
  h3 { font-size: var(--font-size-2xl); }
}

@media (min-width: 1024px) {
  h1 { font-size: var(--font-size-5xl); }
  h2 { font-size: var(--font-size-4xl); }
  h3 { font-size: var(--font-size-3xl); }
}

/* ========== HEADER & NAVIGATION ========== */

/* Header Container */
header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 50;
  background: rgba(15, 15, 15, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-border);
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
}

/* Header Inner Container */
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-md) var(--spacing-lg);
  gap: var(--spacing-lg);
  max-width: 1280px;
  margin: 0 auto;
}

@media (max-width: 1024px) {
  .header-inner {
    padding: var(--spacing-md);
  }
}

/* Logo Section */
.header-logo {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  flex-shrink: 0;
  min-width: fit-content;
}

.header-logo-img {
  height: 40px;
  width: auto;
  transition: transform var(--transition-normal);
}

.header-logo-img:hover {
  transform: scale(1.05);
}

.header-logo-text {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.header-logo-text-main {
  font-size: var(--font-size-lg);
  font-weight: 700;
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.5px;
}

.header-logo-text-sub {
  font-size: var(--font-size-xs);
  color: var(--color-text-secondary);
  white-space: nowrap;
}

@media (max-width: 640px) {
  .header-logo-text-sub {
    display: none;
  }
}

/* Navigation (Desktop) */
.header-nav {
  display: none;
  align-items: center;
  gap: var(--spacing-xl);
  flex: 1;
  justify-content: center;
}

@media (min-width: 1025px) {
  .header-nav {
    display: flex;
  }
}

.header-nav-item {
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
  font-weight: 500;
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.header-nav-item:hover {
  color: var(--color-secondary);
  background: rgba(34, 211, 238, 0.1);
}

.header-nav-item.active {
  color: var(--color-secondary);
  border-bottom: 2px solid var(--color-secondary);
}

/* Auth Section (Right Side) */
.header-auth {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  flex-shrink: 0;
}

/* Auth Buttons */
.header-auth-button {
  padding: 8px 16px;
  font-size: var(--font-size-sm);
  font-weight: 600;
  border-radius: var(--radius-lg);
  transition: all var(--transition-fast);
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  white-space: nowrap;
}

.header-auth-login {
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-light));
  color: white;
  box-shadow: 0 2px 8px rgba(76, 94, 247, 0.2);
}

.header-auth-login:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(76, 94, 247, 0.3);
}

.header-auth-signup {
  background: linear-gradient(135deg, var(--color-secondary), #0891b2);
  color: white;
  box-shadow: 0 2px 8px rgba(34, 211, 238, 0.2);
}

.header-auth-signup:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(34, 211, 238, 0.3);
}

.header-auth-user {
  background: linear-gradient(135deg, var(--color-success), #059669);
  color: white;
  padding: 8px 16px;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: var(--font-size-sm);
  font-weight: 600;
}

.header-auth-user:hover {
  transform: translateY(-2px);
}

.header-auth-logout {
  background: linear-gradient(135deg, var(--color-error), #dc2626);
  color: white;
  box-shadow: 0 2px 8px rgba(239, 68, 68, 0.2);
}

.header-auth-logout:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(239, 68, 68, 0.3);
}

/* Mobile Menu Toggle */
.header-menu-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  background: rgba(34, 211, 238, 0.1);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  color: var(--color-text-primary);
  font-size: 20px;
  cursor: pointer;
  transition: all var(--transition-fast);
  border: none;
  padding: 0;
}

.header-menu-toggle:hover {
  background: rgba(34, 211, 238, 0.2);
  transform: scale(1.05);
}

@media (min-width: 1025px) {
  .header-menu-toggle {
    display: none;
  }
}

/* Mobile Menu (Overlay) */
.mobile-menu-overlay {
  display: none;
  position: fixed;
  top: 64px;
  left: 0;
  width: 100%;
  height: calc(100vh - 64px);
  background: rgba(15, 15, 15, 0.98);
  backdrop-filter: blur(10px);
  z-index: 40;
  overflow-y: auto;
  padding: var(--spacing-lg);
  border-top: 1px solid var(--color-border);
}

.mobile-menu-overlay.active {
  display: block;
  animation: slideDown 0.3s ease-out;
}

@media (min-width: 1025px) {
  .mobile-menu-overlay {
    display: none !important;
  }
}

/* Mobile Navigation */
.mobile-nav {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
}

.mobile-nav-item {
  color: var(--color-text-secondary);
  font-size: var(--font-size-lg);
  font-weight: 500;
  padding: var(--spacing-md);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  border-bottom: 1px solid var(--color-border);
}

.mobile-nav-item:hover,
.mobile-nav-item.active {
  color: var(--color-secondary);
  background: rgba(34, 211, 238, 0.1);
}

/* Mobile Auth Section */
.mobile-auth {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  padding-top: var(--spacing-lg);
  border-top: 1px solid var(--color-border);
  margin-top: var(--spacing-lg);
}

.mobile-auth-button {
  width: 100%;
  padding: 12px 16px;
  font-size: var(--font-size-base);
  font-weight: 600;
  border-radius: var(--radius-lg);
  transition: all var(--transition-fast);
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}

/* Breadcrumb */
.breadcrumb-container {
  display: none;
  padding: var(--spacing-md) var(--spacing-lg);
  border-top: 1px solid var(--color-border);
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  background: rgba(0, 0, 0, 0.2);
}

.breadcrumb-container.visible {
  display: block;
}

/* ========== BUTTONS ========== */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  border: none;
  border-radius: var(--radius-lg);
  font-weight: 600;
  font-size: var(--font-size-base);
  cursor: pointer;
  transition: all var(--transition-normal);
  min-height: 44px;
  padding: var(--spacing-sm) var(--spacing-lg);
  position: relative;
  overflow: hidden;
}

/* Button Sizes */
.btn-sm {
  min-height: 36px;
  font-size: var(--font-size-sm);
  padding: 8px 16px;
}

.btn-md {
  min-height: 44px;
  font-size: var(--font-size-base);
  padding: 12px 24px;
}

.btn-lg {
  min-height: 52px;
  font-size: var(--font-size-lg);
  padding: 16px 32px;
}

/* Button Variants */
.btn-primary {
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-light));
  color: white;
  box-shadow: 0 4px 15px rgba(76, 94, 247, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(76, 94, 247, 0.4);
}

.btn-secondary {
  background: linear-gradient(135deg, var(--color-secondary), #0891b2);
  color: white;
  box-shadow: 0 4px 15px rgba(34, 211, 238, 0.3);
}

.btn-secondary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(34, 211, 238, 0.4);
}

.btn-success {
  background: linear-gradient(135deg, var(--color-success), #059669);
  color: white;
  box-shadow: 0 4px 15px rgba(16, 185, 129, 0.3);
}

.btn-success:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(16, 185, 129, 0.4);
}

.btn-outline {
  background: transparent;
  border: 2px solid var(--color-border);
  color: var(--color-text);
}

.btn-outline:hover {
  border-color: var(--color-secondary);
  background: rgba(34, 211, 238, 0.05);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

/* Mobile-first: Full width buttons on small screens */
@media (max-width: 640px) {
  .btn-fullwidth {
    width: 100%;
  }
}

/* ========== FORM ELEMENTS ========== */

.form-group {
  margin-bottom: var(--spacing-lg);
}

.form-label {
  display: block;
  font-size: var(--font-size-sm);
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
  color: var(--color-text);
}

.form-input,
.form-textarea,
.form-select {
  width: 100%;
  min-height: 44px;
  padding: 12px 16px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.05);
  color: var(--color-text);
  font-family: var(--font-primary);
  font-size: var(--font-size-base);
  transition: all var(--transition-normal);
}

.form-input::placeholder,
.form-textarea::placeholder {
  color: var(--color-text-secondary);
}

.form-input:focus,
.form-textarea:focus,
.form-select:focus {
  outline: none;
  border-color: var(--color-primary);
  background: rgba(255, 255, 255, 0.08);
  box-shadow: 0 0 0 3px rgba(76, 94, 247, 0.1);
}

.form-textarea {
  resize: vertical;
  min-height: 120px;
}

.form-error {
  display: block;
  color: var(--color-error);
  font-size: var(--font-size-xs);
  margin-top: var(--spacing-xs);
}

.form-success {
  display: block;
  color: var(--color-success);
  font-size: var(--font-size-xs);
  margin-top: var(--spacing-xs);
}

/* ========== CARD COMPONENT ========== */

.card {
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  transition: all var(--transition-normal);
  display: flex;
  flex-direction: column;
}

.card:hover {
  transform: translateY(-4px);
  background: rgba(255, 255, 255, 0.04);
  border-color: rgba(255, 255, 255, 0.1);
  box-shadow: var(--shadow-lg);
}

.card-icon {
  width: 60px;
  height: 60px;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--spacing-md);
  background: linear-gradient(135deg, rgba(76, 94, 247, 0.15), rgba(34, 211, 238, 0.15));
  font-size: 24px;
  color: var(--color-secondary);
}

.card-title {
  font-size: var(--font-size-lg);
  font-weight: 700;
  margin-bottom: var(--spacing-sm);
  color: var(--color-text);
}

.card-description {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-md);
  flex-grow: 1;
}

.card-link {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
  color: var(--color-secondary);
  font-weight: 600;
  font-size: var(--font-size-sm);
  transition: gap var(--transition-fast);
}

.card-link:hover {
  gap: var(--spacing-md);
}

/* ========== HEADER & NAVIGATION ========== */

header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: rgba(15, 15, 15, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-border);
}

.header-container {
  max-width: 1280px;
  margin: 0 auto;
  padding: var(--spacing-md) var(--spacing-md);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.header-logo {
  font-size: 24px;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.header-nav {
  display: none;
  gap: var(--spacing-xl);
  align-items: center;
}

.header-nav a {
  color: var(--color-text-secondary);
  transition: color var(--transition-fast);
  font-size: var(--font-size-sm);
}

.header-nav a:hover {
  color: var(--color-secondary);
}

.header-auth {
  display: none;
  gap: var(--spacing-md);
  align-items: center;
}

.mobile-menu-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border: none;
  background: transparent;
  color: var(--color-text);
  cursor: pointer;
  font-size: 24px;
}

/* Tablet and up */
@media (min-width: 768px) {
  .header-container {
    padding: var(--spacing-lg) var(--spacing-xl);
  }
  
  .header-nav {
    display: flex;
  }
  
  .header-auth {
    display: flex;
  }
  
  .mobile-menu-btn {
    display: none;
  }
}

/* ========== HERO SECTION ========== */

.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  padding: var(--spacing-xl) var(--spacing-md);
}

.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(76, 94, 247, 0.1), rgba(34, 211, 238, 0.1));
  z-index: -2;
}

.hero::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, transparent 0%, rgba(15, 15, 15, 0.5) 100%);
  z-index: -1;
}

.hero-content {
  max-width: 800px;
  text-align: center;
  animation: fadeInUp 0.8s ease-in-out;
}

.hero-title {
  font-size: var(--font-size-3xl);
  font-weight: 800;
  margin-bottom: var(--spacing-md);
  background: linear-gradient(135deg, #ffffff, var(--color-secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  animation: float 3s ease-in-out infinite;
}

.hero-subtitle {
  font-size: var(--font-size-lg);
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-2xl);
  line-height: var(--line-height-relaxed);
}

.hero-cta {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  justify-content: center;
}

@media (min-width: 640px) {
  .hero {
    padding: var(--spacing-3xl) var(--spacing-xl);
  }
  
  .hero-title {
    font-size: var(--font-size-4xl);
  }
  
  .hero-cta {
    flex-direction: row;
  }
}

@media (min-width: 1024px) {
  .hero {
    min-height: 100vh;
    padding: var(--spacing-3xl) var(--spacing-2xl);
  }
  
  .hero-title {
    font-size: var(--font-size-5xl);
  }
}

/* ========== SECTION COMMON ========== */

section {
  padding: var(--spacing-2xl) var(--spacing-md);
}

section h2 {
  margin-bottom: var(--spacing-lg);
}

section > p {
  max-width: 600px;
  margin: 0 auto var(--spacing-2xl);
  text-align: center;
}

@media (min-width: 768px) {
  section {
    padding: var(--spacing-3xl) var(--spacing-xl);
  }
}

/* ========== GRID LAYOUTS ========== */

.grid {
  display: grid;
  gap: var(--spacing-md);
}

/* Mobile: 1 column */
.grid-cols-1 { grid-template-columns: 1fr; }

/* Tablet: 2 columns */
@media (min-width: 640px) {
  .grid-cols-2 { grid-template-columns: repeat(2, 1fr); }
}

/* Desktop: 3+ columns */
@media (min-width: 1024px) {
  .grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
  .grid-cols-4 { grid-template-columns: repeat(4, 1fr); }
  .grid { gap: var(--spacing-lg); }
}

/* ========== ANIMATIONS ========== */

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

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

@keyframes slideInLeft {
  from {
    opacity: 0;
    transform: translateX(-20px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes slideInRight {
  from {
    opacity: 0;
    transform: translateX(20px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes pulse {
  0%, 100% {
    opacity: 1;
  }
  50% {
    opacity: 0.5;
  }
}

/* AOS Enhancements */
.aos-init[data-aos] {
  opacity: 0;
}

.aos-animate {
  opacity: 1 !important;
}

/* ========== FOOTER ========== */

footer {
  background: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
  padding: var(--spacing-2xl) var(--spacing-md);
  margin-top: var(--spacing-3xl);
}

.footer-container {
  max-width: 1280px;
  margin: 0 auto;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--spacing-xl);
  margin-bottom: var(--spacing-2xl);
}

@media (min-width: 640px) {
  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .footer-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

.footer-section h4 {
  font-size: var(--font-size-sm);
  font-weight: 700;
  margin-bottom: var(--spacing-md);
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--color-text);
}

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

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

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

.footer-divider {
  height: 1px;
  background: var(--color-border);
  margin: var(--spacing-xl) 0;
}

.footer-bottom {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  align-items: center;
  text-align: center;
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
}

@media (min-width: 768px) {
  .footer-bottom {
    flex-direction: row;
    justify-content: space-between;
  }
  
  footer {
    padding: var(--spacing-3xl) var(--spacing-xl);
  }
}

/* ========== UTILITY CLASSES ========== */

.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

@media (min-width: 768px) {
  .container {
    padding: 0 var(--spacing-xl);
  }
}

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

.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }

.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.mb-xl { margin-bottom: var(--spacing-xl); }

.gap-sm { gap: var(--spacing-sm); }
.gap-md { gap: var(--spacing-md); }
.gap-lg { gap: var(--spacing-lg); }

.flex { display: flex; }
.flex-col { flex-direction: column; }
.flex-center { justify-content: center; align-items: center; }
.flex-between { justify-content: space-between; align-items: center; }

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

@media (max-width: 767px) {
  .hidden-mobile { display: none !important; }
}

@media (min-width: 768px) {
  .hidden-desktop { display: none !important; }
}

/* ========== RESPONSIVE OVERRIDES ========== */

@media (max-width: 640px) {
  body {
    font-size: 14px;
  }
  
  h1 { font-size: var(--font-size-2xl); }
  h2 { font-size: var(--font-size-xl); }
  h3 { font-size: var(--font-size-lg); }
  
  section {
    padding: var(--spacing-lg) var(--spacing-md);
  }
  
  .btn {
    min-height: 40px;
    padding: 10px 16px;
  }
}

/* ========== PRINT STYLES ========== */

@media print {
  header, footer, .no-print {
    display: none !important;
  }
  
  body {
    background: white;
    color: black;
  }
}

/* ========== ADVANCED COMPONENTS ========== */

/* MODAL DIALOG */
.modal {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 1000;
  background: rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(4px);
  align-items: center;
  justify-content: center;
  padding: var(--spacing-md);
}

.modal.active {
  display: flex;
  animation: fadeIn var(--transition-fast) ease-in-out;
}

.modal-content {
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--spacing-lg);
  max-width: 500px;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: var(--shadow-xl);
}

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

.modal-title {
  font-size: var(--font-size-xl);
  font-weight: 700;
}

.modal-close {
  width: 40px;
  height: 40px;
  border: none;
  background: transparent;
  color: var(--color-text-secondary);
  cursor: pointer;
  font-size: 24px;
  transition: color var(--transition-fast);
}

.modal-close:hover {
  color: var(--color-text);
}

.modal-body {
  margin-bottom: var(--spacing-lg);
}

.modal-footer {
  display: flex;
  gap: var(--spacing-md);
  border-top: 1px solid var(--color-border);
  padding-top: var(--spacing-md);
}

/* DROPDOWN MENU */
.dropdown {
  position: relative;
  display: inline-block;
}

.dropdown-toggle {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
  background: none;
  border: none;
  color: var(--color-text);
  cursor: pointer;
  padding: var(--spacing-sm) var(--spacing-md);
  font-weight: 600;
}

.dropdown-menu {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  min-width: 200px;
  margin-top: var(--spacing-sm);
  box-shadow: var(--shadow-lg);
  z-index: 100;
  animation: slideInDown var(--transition-normal) ease-in-out;
}

.dropdown-menu.active {
  display: block;
}

.dropdown-item {
  display: block;
  width: 100%;
  text-align: left;
  padding: var(--spacing-md) var(--spacing-lg);
  color: var(--color-text-secondary);
  background: none;
  border: none;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.dropdown-item:hover {
  background: rgba(255, 255, 255, 0.05);
  color: var(--color-secondary);
}

.dropdown-item.active {
  background: rgba(76, 94, 247, 0.1);
  color: var(--color-primary);
}

.dropdown-divider {
  height: 1px;
  background: var(--color-border);
  margin: 0;
}

/* ACCORDION */
.accordion {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.accordion-item {
  border-bottom: 1px solid var(--color-border);
}

.accordion-item:last-child {
  border-bottom: none;
}

.accordion-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
  padding: var(--spacing-lg);
  background: transparent;
  border: none;
  cursor: pointer;
  transition: all var(--transition-normal);
  gap: var(--spacing-md);
  font-weight: 600;
  color: var(--color-text);
}

.accordion-header:hover {
  background: rgba(255, 255, 255, 0.02);
}

.accordion-header.active {
  background: rgba(76, 94, 247, 0.05);
  color: var(--color-secondary);
}

.accordion-icon {
  width: 24px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform var(--transition-normal);
}

.accordion-header.active .accordion-icon {
  transform: rotate(180deg);
}

.accordion-content {
  display: none;
  padding: 0 var(--spacing-lg) var(--spacing-lg);
  color: var(--color-text-secondary);
  animation: slideDown var(--transition-normal) ease-in-out;
}

.accordion-content.active {
  display: block;
}

/* TABS */
.tabs {
  display: flex;
  border-bottom: 2px solid var(--color-border);
  gap: var(--spacing-md);
  overflow-x: auto;
  margin-bottom: var(--spacing-lg);
}

.tab-btn {
  padding: var(--spacing-md) var(--spacing-lg);
  background: none;
  border: none;
  border-bottom: 3px solid transparent;
  color: var(--color-text-secondary);
  cursor: pointer;
  font-weight: 600;
  transition: all var(--transition-normal);
  white-space: nowrap;
}

.tab-btn:hover {
  color: var(--color-text);
}

.tab-btn.active {
  color: var(--color-secondary);
  border-bottom-color: var(--color-secondary);
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
  animation: fadeIn var(--transition-normal) ease-in-out;
}

/* BREADCRUMBS */
.breadcrumbs {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-lg);
  flex-wrap: wrap;
}

.breadcrumb-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.breadcrumb-item a {
  color: var(--color-secondary);
  transition: color var(--transition-fast);
}

.breadcrumb-item a:hover {
  color: #06b6d4;
  text-decoration: underline;
}

.breadcrumb-item.active {
  color: var(--color-text);
}

.breadcrumb-separator {
  color: var(--color-border);
}

/* TAGS */
.tag {
  display: inline-block;
  padding: 6px 12px;
  background: rgba(76, 94, 247, 0.1);
  color: var(--color-primary);
  border-radius: var(--radius-full);
  font-size: var(--font-size-xs);
  font-weight: 600;
}

.tag-primary { background: rgba(76, 94, 247, 0.1); color: var(--color-primary); }
.tag-secondary { background: rgba(34, 211, 238, 0.1); color: var(--color-secondary); }
.tag-success { background: rgba(16, 185, 129, 0.1); color: var(--color-success); }
.tag-warning { background: rgba(249, 115, 22, 0.1); color: var(--color-warning); }
.tag-error { background: rgba(239, 68, 68, 0.1); color: var(--color-error); }

/* BADGE */
.badge {
  display: inline-block;
  padding: 4px 8px;
  background: var(--color-primary);
  color: white;
  border-radius: var(--radius-full);
  font-size: 11px;
  font-weight: 700;
  line-height: 1;
}

.badge-secondary { background: var(--color-secondary); }
.badge-success { background: var(--color-success); }
.badge-warning { background: var(--color-warning); }
.badge-error { background: var(--color-error); }

/* TOAST NOTIFICATION */
.toast-container {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 2000;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  max-width: 400px;
}

.toast {
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-left: 4px solid var(--color-primary);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  display: flex;
  gap: var(--spacing-md);
  align-items: flex-start;
  box-shadow: var(--shadow-lg);
  animation: slideInRight var(--transition-normal) ease-in-out;
}

.toast-success { border-left-color: var(--color-success); }
.toast-error { border-left-color: var(--color-error); }
.toast-warning { border-left-color: var(--color-warning); }
.toast-info { border-left-color: var(--color-secondary); }

.toast-icon {
  flex-shrink: 0;
  font-size: 20px;
}

.toast-content {
  flex: 1;
}

.toast-title {
  font-weight: 600;
  margin-bottom: 4px;
}

.toast-message {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

.toast-close {
  flex-shrink: 0;
  background: none;
  border: none;
  color: var(--color-text-secondary);
  cursor: pointer;
  padding: 0;
  font-size: 16px;
}

/* LOADING SPINNER */
.spinner {
  display: inline-block;
  width: 20px;
  height: 20px;
  border: 3px solid rgba(255, 255, 255, 0.3);
  border-top-color: var(--color-secondary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

.spinner-sm {
  width: 16px;
  height: 16px;
  border-width: 2px;
}

.spinner-lg {
  width: 32px;
  height: 32px;
  border-width: 4px;
}

/* PROGRESS BAR */
.progress {
  width: 100%;
  height: 8px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: var(--radius-full);
  overflow: hidden;
}

.progress-bar {
  height: 100%;
  background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
  border-radius: var(--radius-full);
  transition: width var(--transition-normal);
}

/* ALERT */
.alert {
  padding: var(--spacing-lg);
  border-radius: var(--radius-lg);
  border-left: 4px solid;
  display: flex;
  gap: var(--spacing-md);
  align-items: flex-start;
}

.alert-primary {
  background: rgba(76, 94, 247, 0.1);
  border-left-color: var(--color-primary);
  color: var(--color-text);
}

.alert-success {
  background: rgba(16, 185, 129, 0.1);
  border-left-color: var(--color-success);
  color: var(--color-text);
}

.alert-warning {
  background: rgba(249, 115, 22, 0.1);
  border-left-color: var(--color-warning);
  color: var(--color-text);
}

.alert-error {
  background: rgba(239, 68, 68, 0.1);
  border-left-color: var(--color-error);
  color: var(--color-text);
}

.alert-icon {
  flex-shrink: 0;
  font-size: 18px;
}

.alert-content {
  flex: 1;
}

.alert-title {
  font-weight: 600;
  margin-bottom: 4px;
}

.alert-message {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

/* ADDITIONAL ANIMATIONS */
@keyframes slideInDown {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes slideDown {
  from {
    opacity: 0;
    max-height: 0;
  }
  to {
    opacity: 1;
    max-height: 500px;
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}