/* Global Responsive CSS for IT Interview Hub */
/* Mobile-first responsive design system */

/* CSS Variables for responsive breakpoints */
:root {
  --breakpoint-xs: 480px;
  --breakpoint-sm: 640px;
  --breakpoint-md: 768px;
  --breakpoint-lg: 1024px;
  --breakpoint-xl: 1200px;
  --breakpoint-2xl: 1400px;
  
  /* Responsive spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 1.5rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  --spacing-2xl: 4rem;
  
  /* Responsive font sizes */
  --font-xs: 0.75rem;
  --font-sm: 0.875rem;
  --font-base: 1rem;
  --font-lg: 1.125rem;
  --font-xl: 1.25rem;
  --font-2xl: 1.5rem;
  --font-3xl: 1.875rem;
  --font-4xl: 2.25rem;
}

/* Base responsive styles */
* {
  box-sizing: border-box;
}

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  line-height: 1.6;
  color: #0f172a;
  margin: 0;
  padding: 0;
  overflow-x: hidden;
}

/* Container responsive system */
.container {
  width: 100%;
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 1rem;
}

@media (min-width: 640px) {
  .container {
    padding: 0 1.5rem;
  }
}

@media (min-width: 1024px) {
  .container {
    padding: 0 2rem;
  }
}

@media (min-width: 1400px) {
  .container {
    padding: 0 3rem;
  }
}

/* Grid system */
.grid {
  display: grid;
  gap: 1rem;
}

.grid-cols-1 { grid-template-columns: repeat(1, 1fr); }
.grid-cols-2 { grid-template-columns: repeat(2, 1fr); }
.grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
.grid-cols-4 { grid-template-columns: repeat(4, 1fr); }

@media (min-width: 640px) {
  .sm\:grid-cols-1 { grid-template-columns: repeat(1, 1fr); }
  .sm\:grid-cols-2 { grid-template-columns: repeat(2, 1fr); }
  .sm\:grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
  .sm\:grid-cols-4 { grid-template-columns: repeat(4, 1fr); }
}

@media (min-width: 768px) {
  .md\:grid-cols-1 { grid-template-columns: repeat(1, 1fr); }
  .md\:grid-cols-2 { grid-template-columns: repeat(2, 1fr); }
  .md\:grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
  .md\:grid-cols-4 { grid-template-columns: repeat(4, 1fr); }
}

@media (min-width: 1024px) {
  .lg\:grid-cols-1 { grid-template-columns: repeat(1, 1fr); }
  .lg\:grid-cols-2 { grid-template-columns: repeat(2, 1fr); }
  .lg\:grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
  .lg\:grid-cols-4 { grid-template-columns: repeat(4, 1fr); }
}

/* Flexbox utilities */
.flex {
  display: flex;
}

.flex-col {
  flex-direction: column;
}

.flex-wrap {
  flex-wrap: wrap;
}

.items-center {
  align-items: center;
}

.justify-center {
  justify-content: center;
}

.justify-between {
  justify-content: space-between;
}

/* Responsive typography */
.text-xs { font-size: var(--font-xs); }
.text-sm { font-size: var(--font-sm); }
.text-base { font-size: var(--font-base); }
.text-lg { font-size: var(--font-lg); }
.text-xl { font-size: var(--font-xl); }
.text-2xl { font-size: var(--font-2xl); }
.text-3xl { font-size: var(--font-3xl); }
.text-4xl { font-size: var(--font-4xl); }

@media (min-width: 768px) {
  .md\:text-xs { font-size: var(--font-xs); }
  .md\:text-sm { font-size: var(--font-sm); }
  .md\:text-base { font-size: var(--font-base); }
  .md\:text-lg { font-size: var(--font-lg); }
  .md\:text-xl { font-size: var(--font-xl); }
  .md\:text-2xl { font-size: var(--font-2xl); }
  .md\:text-3xl { font-size: var(--font-3xl); }
  .md\:text-4xl { font-size: var(--font-4xl); }
}

@media (min-width: 1024px) {
  .lg\:text-xs { font-size: var(--font-xs); }
  .lg\:text-sm { font-size: var(--font-sm); }
  .lg\:text-base { font-size: var(--font-base); }
  .lg\:text-lg { font-size: var(--font-lg); }
  .lg\:text-xl { font-size: var(--font-xl); }
  .lg\:text-2xl { font-size: var(--font-2xl); }
  .lg\:text-3xl { font-size: var(--font-3xl); }
  .lg\:text-4xl { font-size: var(--font-4xl); }
}

/* Responsive spacing */
.p-1 { padding: var(--spacing-xs); }
.p-2 { padding: var(--spacing-sm); }
.p-3 { padding: var(--spacing-md); }
.p-4 { padding: var(--spacing-lg); }
.p-5 { padding: var(--spacing-xl); }
.p-6 { padding: var(--spacing-2xl); }

.m-1 { margin: var(--spacing-xs); }
.m-2 { margin: var(--spacing-sm); }
.m-3 { margin: var(--spacing-md); }
.m-4 { margin: var(--spacing-lg); }
.m-5 { margin: var(--spacing-xl); }
.m-6 { margin: var(--spacing-2xl); }

.mt-1 { margin-top: var(--spacing-xs); }
.mt-2 { margin-top: var(--spacing-sm); }
.mt-3 { margin-top: var(--spacing-md); }
.mt-4 { margin-top: var(--spacing-lg); }
.mt-5 { margin-top: var(--spacing-xl); }
.mt-6 { margin-top: var(--spacing-2xl); }

.mb-1 { margin-bottom: var(--spacing-xs); }
.mb-2 { margin-bottom: var(--spacing-sm); }
.mb-3 { margin-bottom: var(--spacing-md); }
.mb-4 { margin-bottom: var(--spacing-lg); }
.mb-5 { margin-bottom: var(--spacing-xl); }
.mb-6 { margin-bottom: var(--spacing-2xl); }

/* Responsive buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  font-size: 0.875rem;
  font-weight: 500;
  text-decoration: none;
  border-radius: 0.5rem;
  transition: all 0.3s ease;
  cursor: pointer;
  border: none;
  min-height: 44px; /* Touch target size */
  white-space: nowrap;
}

@media (max-width: 640px) {
  .btn {
    padding: 0.65rem 1.25rem;
    font-size: 0.8rem;
    min-height: 40px;
  }
}

@media (max-width: 480px) {
  .btn {
    padding: 0.6rem 1rem;
    font-size: 0.75rem;
    min-height: 36px;
  }
}

.btn-primary {
  background: linear-gradient(135deg, #2563eb, #1e40af);
  color: white;
  box-shadow: 0 4px 6px -1px rgba(37, 99, 235, 0.2);
}

.btn-primary:hover {
  background: linear-gradient(135deg, #1d4ed8, #1e3a8a);
  transform: translateY(-2px);
  box-shadow: 0 10px 15px -3px rgba(37, 99, 235, 0.3);
}

.btn-secondary {
  background: white;
  color: #2563eb;
  border: 2px solid #2563eb;
}

.btn-secondary:hover {
  background: rgba(37, 99, 235, 0.05);
  transform: translateY(-2px);
}

/* Responsive cards */
.card {
  background: white;
  border-radius: 0.75rem;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  padding: 1.5rem;
  transition: all 0.3s ease;
  border: 1px solid #e2e8f0;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
}

@media (max-width: 768px) {
  .card {
    padding: 1.25rem;
  }
}

@media (max-width: 480px) {
  .card {
    padding: 1rem;
    border-radius: 0.5rem;
  }
}

/* Responsive navigation */
.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem;
}

@media (max-width: 768px) {
  .nav-container {
    padding: 0.75rem;
  }
}

@media (max-width: 480px) {
  .nav-container {
    padding: 0.5rem;
  }
}

/* Responsive hero section */
.hero {
  padding: 4rem 0;
  text-align: center;
  background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
}

.hero h1 {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: 1rem;
  line-height: 1.2;
}

.hero p {
  font-size: 1.125rem;
  margin-bottom: 2rem;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
  color: #64748b;
}

@media (max-width: 768px) {
  .hero {
    padding: 3rem 0;
  }
  
  .hero h1 {
    font-size: 2rem;
  }
  
  .hero p {
    font-size: 1rem;
    margin-bottom: 1.5rem;
  }
}

@media (max-width: 480px) {
  .hero {
    padding: 2rem 0;
  }
  
  .hero h1 {
    font-size: 1.75rem;
  }
  
  .hero p {
    font-size: 0.95rem;
    margin-bottom: 1.25rem;
  }
}

/* Responsive sections */
.section {
  padding: 4rem 0;
}

.section-title {
  text-align: center;
  margin-bottom: 3rem;
}

.section-title h2 {
  font-size: 2.25rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: #0f172a;
}

.section-title p {
  font-size: 1.125rem;
  color: #64748b;
  max-width: 600px;
  margin: 0 auto;
}

@media (max-width: 768px) {
  .section {
    padding: 3rem 0;
  }
  
  .section-title {
    margin-bottom: 2rem;
  }
  
  .section-title h2 {
    font-size: 1.875rem;
  }
  
  .section-title p {
    font-size: 1rem;
  }
}

@media (max-width: 480px) {
  .section {
    padding: 2rem 0;
  }
  
  .section-title {
    margin-bottom: 1.5rem;
  }
  
  .section-title h2 {
    font-size: 1.5rem;
  }
  
  .section-title p {
    font-size: 0.95rem;
  }
}

/* Responsive topic grid */
.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  margin-bottom: 3rem;
}

.topic-card {
  background: white;
  border-radius: 1rem;
  padding: 2rem;
  text-align: center;
  transition: all 0.3s ease;
  border: 1px solid #e2e8f0;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.topic-card:hover {
  transform: translateY(-8px);
  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
}

.topic-icon {
  width: 80px;
  height: 80px;
  background: linear-gradient(135deg, #2563eb, #1e40af);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 1.5rem;
  color: white;
  font-size: 2rem;
}

.topic-title {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
  color: #0f172a;
}

.topic-meta {
  font-size: 0.875rem;
  color: #64748b;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
}

@media (max-width: 768px) {
  .topics-grid {
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
  }
  
  .topic-card {
    padding: 1.5rem;
  }
  
  .topic-icon {
    width: 60px;
    height: 60px;
    font-size: 1.5rem;
  }
  
  .topic-title {
    font-size: 1.125rem;
  }
  
  .topic-meta {
    font-size: 0.8rem;
  }
}

@media (max-width: 480px) {
  .topics-grid {
    grid-template-columns: 1fr;
    gap: 1.25rem;
    margin-bottom: 1.5rem;
  }
  
  .topic-card {
    padding: 1.25rem;
  }
  
  .topic-icon {
    width: 50px;
    height: 50px;
    font-size: 1.25rem;
  }
  
  .topic-title {
    font-size: 1rem;
  }
  
  .topic-meta {
    font-size: 0.75rem;
  }
}

/* Responsive forms */
.form-group {
  margin-bottom: 1.5rem;
}

.form-label {
  display: block;
  font-weight: 500;
  margin-bottom: 0.5rem;
  color: #374151;
}

.form-input,
.form-textarea {
  width: 100%;
  padding: 0.75rem 1rem;
  border: 2px solid #e5e7eb;
  border-radius: 0.5rem;
  font-size: 1rem;
  transition: border-color 0.3s ease;
}

.form-input:focus,
.form-textarea:focus {
  outline: none;
  border-color: #2563eb;
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

@media (max-width: 480px) {
  .form-input,
  .form-textarea {
    padding: 0.65rem 0.875rem;
    font-size: 0.9rem;
  }
}

/* Responsive tables */
.table-container {
  overflow-x: auto;
  margin-bottom: 2rem;
}

.table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
}

.table th,
.table td {
  padding: 0.75rem;
  text-align: left;
  border-bottom: 1px solid #e5e7eb;
}

@media (max-width: 768px) {
  .table th,
  .table td {
    padding: 0.5rem;
    font-size: 0.8rem;
  }
}

@media (max-width: 480px) {
  .table {
    font-size: 0.75rem;
  }
  
  .table th,
  .table td {
    padding: 0.4rem;
  }
}

/* Responsive sidebar */
.sidebar {
  width: 300px;
  background: white;
  border-radius: 0.75rem;
  padding: 1.5rem;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  position: sticky;
  top: 2rem;
  max-height: calc(100vh - 4rem);
  overflow-y: auto;
}

@media (max-width: 768px) {
  .sidebar {
    width: 100%;
    position: relative;
    top: 0;
    max-height: none;
    margin-bottom: 2rem;
  }
}

/* Responsive footer */
.footer {
  background: #0f172a;
  color: #cbd5f5;
  padding: 3rem 0 2rem;
  margin-top: 4rem;
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
  margin-bottom: 2rem;
}

.footer-section h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: 1rem;
  color: white;
}

.footer-links {
  list-style: none;
  padding: 0;
}

.footer-links li {
  margin-bottom: 0.5rem;
}

.footer-links a {
  color: #94a3b8;
  text-decoration: none;
  transition: color 0.3s ease;
}

.footer-links a:hover {
  color: #2563eb;
}

@media (max-width: 768px) {
  .footer {
    padding: 2rem 0 1.5rem;
    margin-top: 3rem;
  }
  
  .footer-content {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }
}

/* Accessibility and performance */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* Print styles */
@media print {
  .no-print {
    display: none !important;
  }
  
  body {
    font-size: 12pt;
    line-height: 1.4;
    color: black;
    background: white;
  }
  
  .card {
    box-shadow: none;
    border: 1px solid #ccc;
    break-inside: avoid;
  }
}

/* High contrast mode */
@media (prefers-contrast: high) {
  .card {
    border: 2px solid #000;
  }
  
  .btn {
    border: 2px solid currentColor;
  }
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
  body {
    background: #0f172a;
    color: #f1f5f9;
  }
  
  .card {
    background: #1e293b;
    border-color: #334155;
    color: #f1f5f9;
  }
  
  .hero {
    background: linear-gradient(135deg, #1e293b 0%, #334155 100%);
  }
  
  .section-title h2 {
    color: #f1f5f9;
  }
  
  .topic-title {
    color: #f1f5f9;
  }
}