:root {
  /* Colors */
  --bg-dark: #0b1020;
  --surface: #0f1724;
  --surface-light: #1a2332;
  --surface-lighter: #242b3d;
  --primary: #00d1ff;
  --accent: #6c5ce7;
  --success: #22c55e;
  --warning: #f59e0b;
  --danger: #ef4444;
  --text-primary: #ffffff;
  --text-muted: #a9b0c0;
  --text-dim: #6b7280;

  /* Gradients */
  --gradient-primary: linear-gradient(90deg, #00d1ff 0%, #6c5ce7 100%);
  --gradient-success: linear-gradient(90deg, #22c55e 0%, #00d1ff 100%);

  /* Spacing */
  --space-1: 0.5rem;
  --space-2: 1rem;
  --space-3: 1.5rem;
  --space-4: 2rem;
  --space-5: 2.5rem;
  --space-6: 3rem;
  --space-8: 4rem;
  --space-12: 6rem;

  /* Typography */
  --font-heading: "Orbitron", monospace;
  --font-body: "Inter", sans-serif;

  /* Borders & Shadows */
  --radius: 0.5rem;
  --radius-lg: 1rem;
  --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
  --shadow-glow: 0 0 20px rgba(0, 209, 255, 0.3);

  /* Transitions */
  --transition: cubic-bezier(0.2, 0.9, 0.2, 1);
  --duration-fast: 0.15s;
  --duration-normal: 0.3s;
  --duration-slow: 0.6s;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  background: var(--bg-dark);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
  position: relative;
}

/* ===== HIDE SCROLLBAR ===== */
/* Webkit browsers (Chrome, Safari, Edge) */
::-webkit-scrollbar {
  width: 0px;
  background: transparent;
}

/* Firefox */
html {
  scrollbar-width: none;
}

.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;
}

/* ===== TYPOGRAPHY ===== */
h1,
h2,
h3,
h4,
h5,
h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.2;
}

h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 900;
}

h2 {
  font-size: clamp(1.5rem, 4vw, 2.25rem);
  margin-bottom: var(--space-4);
  text-align: center;
}

h3 {
  font-size: clamp(1.25rem, 3vw, 1.5rem);
  margin-bottom: var(--space-2);
}

p {
  margin-bottom: var(--space-3);
  color: var(--text-muted);
}

.section-subtitle {
  text-align: center;
  font-size: 1.125rem;
  margin-bottom: var(--space-6);
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

/* ===== LAYOUT ===== */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-4);
}

@media (max-width: 768px) {
  .container {
    padding: 0 var(--space-2);
  }
}

/* ===== BUTTONS ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-2) var(--space-4);
  border: none;
  border-radius: var(--radius);
  font-family: var(--font-body);
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  transition: all var(--duration-normal) var(--transition);
  position: relative;
  overflow: hidden;
  gap: var(--space-1);
}

.btn--primary {
  background: var(--gradient-primary);
  color: white;
  box-shadow: var(--shadow);
}

.btn--primary:hover,
.btn--primary:focus {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg), var(--shadow-glow);
}

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

.btn--secondary:hover,
.btn--secondary:focus {
  background: var(--primary);
  color: var(--bg-dark);
  transform: translateY(-2px);
}

.btn--small {
  padding: var(--space-1) var(--space-2);
  font-size: 0.875rem;
}

.btn--full {
  width: 100%;
}

.btn:focus {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

.btn-icon {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
}

/* ===== NAVIGATION ===== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: rgba(11, 16, 32, 0.7);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid rgba(0, 209, 255, 0.2);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
  z-index: 100;
  padding: var(--space-2) 0;
  transition: transform 0.3s ease-in-out;
}

/* Mobile navbar hide/show on scroll */
@media (max-width: 768px) {
  .navbar.navbar-hidden {
    transform: translateY(-100%);
  }

  .navbar.navbar-visible {
    transform: translateY(0);
  }
}

/* Navigation active states */
.nav-link {
  position: relative;
  overflow: hidden;
}

.nav-link::before {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gradient-primary);
  transition: width var(--duration-normal) var(--transition);
}

.nav-link:hover::before {
  width: 100%;
}

.nav-link.active {
  color: var(--primary);
  background: rgba(0, 209, 255, 0.1);
}

.nav-link.active::before {
  width: 100%;
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-4);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--text-primary);
}

.nav-logo {
  flex-shrink: 0;
}

.nav-menu {
  display: flex;
  gap: var(--space-2);
}

.nav-link {
  color: var(--text-muted);
  text-decoration: none;
  font-weight: 500;
  padding: var(--space-1) var(--space-2);
  border-radius: var(--radius);
  transition: all var(--duration-normal) var(--transition);
}

.nav-link:hover,
.nav-link:focus,
.nav-link.active {
  color: var(--primary);
  background: rgba(0, 209, 255, 0.1);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.streak-display {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-1) var(--space-2);
  background: var(--surface);
  border-radius: var(--radius);
  cursor: pointer;
  transition: all var(--duration-normal) var(--transition);
}

.streak-display:hover {
  background: var(--surface-light);
  transform: scale(1.05);
}

.streak-flame {
  font-size: 1.2em;
}

.streak-count {
  font-weight: 600;
  color: var(--text-primary);
}

/* ===== MAIN CONTENT ===== */
.demo-main {
  margin-top: 80px;
}

@media (max-width: 768px) {
  .demo-main {
    margin-top: 140px;
  }

  .dashboard-header {
    padding-top: var(--space-4);
    margin-bottom: var(--space-6);
  }

  .dashboard-header h1 {
    font-size: clamp(1.8rem, 6vw, 2.5rem);
    margin-bottom: var(--space-3);
    padding-top: 18px;
  }

  .dashboard-header p {
    font-size: 1rem;
    margin-bottom: var(--space-4);
  }
}

@media (max-width: 480px) {
  .demo-main {
    margin-top: 120px;
  }

  .dashboard-header {
    padding-top: var(--space-2);
    margin-bottom: var(--space-4);
  }

  .dashboard-header h1 {
    font-size: clamp(1.5rem, 8vw, 2rem);
    margin-bottom: var(--space-2);
  }

  .dashboard-header p {
    font-size: 0.9rem;
    margin-bottom: var(--space-3);
  }
}

section {
  padding: var(--space-8) 0;
}

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

/* ===== DASHBOARD ===== */
.dashboard-header {
  text-align: center;
  margin-bottom: var(--space-8);
}

.dashboard-header h1 {
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: var(--space-2);
}

.dashboard-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--space-4);
}

.dashboard-card {
  background: var(--surface-light);
  padding: var(--space-4);
  border-radius: var(--radius-lg);
  border: 1px solid var(--surface-lighter);
  transition: all var(--duration-normal) var(--transition);
  display: flex;
  flex-direction: column;
  height: 100%;
}

.dashboard-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary);
}

.dashboard-card h3 {
  color: var(--text-primary);
  margin-bottom: var(--space-3);
  text-align: center;
}

/* Streak Overview Card */
.streak-overview {
  text-align: center;
}

.streak-overview .btn {
  margin-top: auto;
  display: block;
  width: fit-content;
  align-self: center;
}

/* Dashboard card button alignment */
.dashboard-card .btn {
  margin-top: auto;
  align-self: center;
}

/* Streak Overview */
.streak-display-large {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  margin: var(--space-4) 0;
}

.streak-number {
  font-size: 3rem;
  font-weight: 900;
  font-family: var(--font-heading);
  color: var(--text-primary);
  line-height: 1;
}

.streak-label {
  color: var(--text-muted);
  font-size: 1rem;
}

.streak-icon {
  font-size: 2.5rem;
  animation: flicker 2s ease-in-out infinite alternate;
}

@keyframes flicker {
  0%,
  100% {
    opacity: 1;
    filter: drop-shadow(0 0 5px #ff6b35);
  }
  50% {
    opacity: 0.8;
    filter: drop-shadow(0 0 10px #ff6b35);
  }
}

.streak-message {
  text-align: center;
  margin-bottom: var(--space-3);
  font-style: italic;
}

/* Stats Card */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-3);
}

.stat-item {
  text-align: center;
  padding: var(--space-2);
  background: var(--surface);
  border-radius: var(--radius);
}

.stat-number {
  font-size: 2rem;
  font-weight: 700;
  font-family: var(--font-heading);
  color: var(--primary);
  line-height: 1;
}

.stat-label {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-top: var(--space-1);
}

/* Today's Challenge */
.challenge-preview {
  text-align: center;
}

.challenge-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-1);
}

.challenge-difficulty {
  display: inline-block;
  padding: var(--space-1) var(--space-2);
  border-radius: var(--radius);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  margin-bottom: var(--space-2);
}

.challenge-difficulty.easy {
  background: rgba(34, 197, 94, 0.2);
  color: var(--success);
}

.challenge-desc {
  margin-bottom: var(--space-3);
}

.challenge-stats {
  display: flex;
  justify-content: center;
  gap: var(--space-3);
  margin-bottom: var(--space-3);
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* ===== CHALLENGES SECTION ===== */
.challenges-filter {
  display: flex;
  justify-content: center;
  gap: var(--space-2);
  margin-top: var(--space-6);
  margin-bottom: var(--space-6);
  flex-wrap: wrap;
  padding-top: var(--space-2);
}

.filter-btn {
  padding: var(--space-2) var(--space-3);
  background: var(--surface-light);
  color: var(--text-muted);
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
  transition: all var(--duration-normal) var(--transition);
  font-weight: 500;
}

.filter-btn:hover,
.filter-btn.active {
  background: var(--primary);
  color: white;
  transform: translateY(-2px);
}

.challenges-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: var(--space-4);
}

.challenge-card {
  background: var(--surface-light);
  padding: var(--space-4);
  border-radius: var(--radius-lg);
  border: 1px solid var(--surface-lighter);
  transition: all var(--duration-normal) var(--transition);
  display: flex;
  flex-direction: column;
  height: 100%;
}

.challenge-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary);
}

.challenge-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-2);
}

.challenge-header h3 {
  margin: 0;
  color: var(--text-primary);
}

.difficulty {
  padding: var(--space-1) var(--space-2);
  border-radius: var(--radius);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
}

.difficulty.easy {
  background: rgba(34, 197, 94, 0.2);
  color: var(--success);
}

.difficulty.medium {
  background: rgba(245, 158, 11, 0.2);
  color: var(--warning);
}

.difficulty.hard {
  background: rgba(239, 68, 68, 0.2);
  color: var(--danger);
}

.challenge-meta {
  display: flex;
  gap: var(--space-3);
  margin: var(--space-3) 0;
  font-size: 0.875rem;
  color: var(--text-muted);
  flex-grow: 1;
  align-items: flex-end;
  margin-bottom: var(--space-4);
}

.challenge-card .btn {
  margin-top: auto;
}

/* ===== PROJECTS SECTION ===== */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: var(--space-4);
}

.project-card {
  background: var(--surface-light);
  border-radius: var(--radius-lg);
  border: 1px solid var(--surface-lighter);
  overflow: hidden;
  transition: all var(--duration-normal) var(--transition);
  display: flex;
  flex-direction: column;
  height: 100%;
}

.project-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary);
}

.project-image {
  height: 200px;
  background: var(--surface);
  display: flex;
  align-items: center;
  justify-content: center;
  border-bottom: 1px solid var(--surface-lighter);
}

.project-placeholder {
  font-size: 4rem;
  opacity: 0.5;
}

.project-content {
  padding: var(--space-4);
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  flex-grow: 1;
}

.project-content .btn {
  margin-top: auto;
  align-self: center;
}

.project-content h3 {
  color: var(--text-primary);
  margin-bottom: var(--space-2);
}

.project-tech {
  display: flex;
  gap: var(--space-1);
  margin: var(--space-3) 0;
  flex-wrap: wrap;
}

.tech-tag {
  padding: var(--space-1) var(--space-2);
  background: var(--surface);
  color: var(--primary);
  border-radius: var(--radius);
  font-size: 0.75rem;
  font-weight: 500;
}

.project-meta {
  display: flex;
  gap: var(--space-3);
  margin: var(--space-3) 0 var(--space-4) 0;
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* ===== INTERVIEW PREP SECTION ===== */
.interview-categories {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-4);
  margin-bottom: var(--space-8);
}

.category-card {
  background: var(--surface-light);
  padding: var(--space-4);
  border-radius: var(--radius-lg);
  border: 1px solid var(--surface-lighter);
  text-align: center;
  transition: all var(--duration-normal) var(--transition);
  display: flex;
  flex-direction: column;
  height: 100%;
}

.category-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary);
}

.category-icon {
  font-size: 3rem;
  margin-bottom: var(--space-2);
}

.category-card h3 {
  color: var(--text-primary);
  margin-bottom: var(--space-2);
}

.category-stats {
  display: flex;
  justify-content: center;
  gap: var(--space-3);
  margin: var(--space-3) 0;
  font-size: 0.875rem;
  color: var(--text-muted);
  flex-grow: 1;
  align-items: flex-end;
  margin-bottom: var(--space-4);
}

.category-card .btn {
  margin-top: auto;
}

.company-prep {
  margin-top: var(--space-8);
}

.company-prep h3 {
  text-align: center;
  margin-bottom: var(--space-4);
  color: var(--text-primary);
}

.company-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: var(--space-3);
}

.company-card {
  background: var(--surface-light);
  padding: var(--space-3);
  border-radius: var(--radius);
  border: 1px solid var(--surface-lighter);
  text-align: center;
  cursor: pointer;
  transition: all var(--duration-normal) var(--transition);
}

.company-card:hover {
  transform: translateY(-2px);
  border-color: var(--primary);
  background: var(--surface-lighter);
}

.company-logo {
  font-size: 2rem;
  margin-bottom: var(--space-1);
}

.company-card h4 {
  color: var(--text-primary);
  margin-bottom: var(--space-1);
  font-size: 1rem;
}

.company-card p {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin: 0;
}

/* ===== COMMUNITY SECTION ===== */
.community-features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-4);
}

.community-card {
  background: var(--surface-light);
  padding: var(--space-4);
  border-radius: var(--radius-lg);
  border: 1px solid var(--surface-lighter);
  text-align: center;
  transition: all var(--duration-normal) var(--transition);
  display: flex;
  flex-direction: column;
  height: 100%;
}

.community-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary);
}

.community-icon {
  font-size: 3rem;
  margin-bottom: var(--space-2);
}

.community-card h3 {
  color: var(--text-primary);
  margin-bottom: var(--space-2);
}

.community-stats {
  display: flex;
  justify-content: center;
  gap: var(--space-3);
  margin: var(--space-3) 0;
  font-size: 0.875rem;
  color: var(--text-muted);
  flex-grow: 1;
  align-items: flex-end;
  margin-bottom: var(--space-4);
}

.community-card .btn {
  margin-top: auto;
}

/* ===== COURSES NOTICE SECTION ===== */
.courses-notice {
  background: var(--surface);
  padding: var(--space-4) 0;
}

.courses-banner {
  background: linear-gradient(
    135deg,
    var(--surface-light) 0%,
    var(--surface-lighter) 100%
  );
  border: 1px solid var(--primary);
  border-radius: var(--radius-lg);
  padding: var(--space-4);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  max-width: 800px;
  margin: 0 auto;
  position: relative;
  overflow: hidden;
}

.courses-banner::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--gradient-primary);
}

.courses-content {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  flex: 1;
}

.courses-icon {
  font-size: 2.5rem;
  flex-shrink: 0;
}

.courses-text h3 {
  color: var(--text-primary);
  margin: 0 0 var(--space-1) 0;
  font-size: 1.25rem;
}

.courses-text p {
  color: var(--text-muted);
  margin: 0;
  font-size: 0.95rem;
}

.courses-banner .btn {
  flex-shrink: 0;
  white-space: nowrap;
}

@media (max-width: 768px) {
  .courses-banner {
    flex-direction: column;
    text-align: center;
  }

  .courses-content {
    flex-direction: column;
    text-align: center;
  }
}

/* ===== LEADERBOARD SECTION ===== */
.leaderboard-tabs {
  display: flex;
  justify-content: center;
  gap: var(--space-1);
  margin-bottom: var(--space-6);
  background: var(--surface-light);
  padding: var(--space-1);
  border-radius: var(--radius);
  width: fit-content;
  margin-left: auto;
  margin-right: auto;
}

.tab-btn {
  padding: var(--space-2) var(--space-4);
  background: transparent;
  color: var(--text-muted);
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
  transition: all var(--duration-normal) var(--transition);
  font-weight: 500;
}

.tab-btn:hover,
.tab-btn.active {
  background: var(--primary);
  color: white;
}

.leaderboard-table {
  background: var(--surface-light);
  border-radius: var(--radius-lg);
  border: 1px solid var(--surface-lighter);
  overflow: hidden;
}

.leaderboard-header {
  display: grid;
  grid-template-columns: 80px 1fr 80px 80px 80px;
  gap: var(--space-2);
  padding: var(--space-3);
  background: var(--surface);
  font-weight: 600;
  color: var(--text-primary);
  border-bottom: 1px solid var(--surface-lighter);
}

.leaderboard-row {
  display: grid;
  grid-template-columns: 80px 1fr 80px 80px 80px;
  gap: var(--space-2);
  padding: var(--space-3);
  border-bottom: 1px solid var(--surface-lighter);
  transition: all var(--duration-normal) var(--transition);
  align-items: center;
}

.leaderboard-row:hover {
  background: var(--surface);
}

.leaderboard-row:last-child {
  border-bottom: none;
}

.leaderboard-row.top-3 {
  background: rgba(0, 209, 255, 0.05);
}

.leaderboard-row.your-rank {
  background: rgba(108, 92, 231, 0.1);
  border: 1px solid var(--accent);
  border-bottom-left-radius: 20px;
  border-bottom-right-radius: 20px;
}

.rank {
  font-weight: 600;
  text-align: center;
}

.user-info {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.user-avatar {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 600;
  font-size: 0.875rem;
}

.streak {
  text-align: center;
}

.xp {
  text-align: center;
  color: var(--primary);
  font-weight: 600;
}

.problems {
  text-align: center;
  color: var(--text-muted);
}

.leaderboard-cta {
  text-align: center;
  margin-top: var(--space-6);
}

.leaderboard-cta p {
  margin-bottom: var(--space-3);
  font-size: 1.125rem;
}

/* ===== MODAL ===== */
#login-modal {
  display: none;
}

.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: rgba(11, 16, 32, 0.8);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: all var(--duration-normal) var(--transition);
}

#login-modal:checked ~ .modal-overlay {
  opacity: 1;
  visibility: visible;
}

.modal {
  background: var(--surface);
  border-radius: var(--radius-lg);
  border: 1px solid var(--surface-light);
  max-width: 500px;
  width: 90%;
  max-height: 90vh;
  overflow-y: auto;
  transform: scale(0.9);
  transition: transform var(--duration-normal) var(--transition);
}

#login-modal:checked ~ .modal-overlay .modal {
  transform: scale(1);
}

.modal__header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--space-4);
  border-bottom: 1px solid var(--surface-light);
}

.modal__header h2 {
  margin: 0;
  font-size: 1.5rem;
  text-align: left;
}

.modal__close {
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-muted);
  transition: color var(--duration-normal) var(--transition);
  padding: var(--space-1);
  line-height: 1;
}

.modal__close:hover {
  color: var(--text-primary);
}

.modal__content {
  padding: var(--space-4);
}

.login-options {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  margin-bottom: var(--space-6);
}

.demo-notice {
  text-align: center;
  padding: var(--space-4);
  background: var(--surface-light);
  border-radius: var(--radius);
  border: 1px solid var(--surface-lighter);
}

.demo-notice h3 {
  color: var(--warning);
  margin-bottom: var(--space-2);
}

.demo-notice p {
  margin-bottom: var(--space-2);
  color: var(--text-muted);
}

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

/* Tablet Styles (768px to 1024px) */
@media (min-width: 768px) and (max-width: 1024px) {
  .container {
    padding: 0 var(--space-3);
  }

  .nav-container {
    padding: 0 var(--space-3);
  }

  .nav-menu {
    gap: var(--space-2);
  }

  .nav-link {
    font-size: 0.9rem;
    padding: var(--space-1) var(--space-2);
  }

  .dashboard-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-5);
  }

  .challenges-grid,
  .projects-grid,
  .interview-categories,
  .community-features {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-4);
  }

  .challenges-filter {
    gap: var(--space-3);
    margin-top: var(--space-5);
    margin-bottom: var(--space-5);
  }

  .filter-btn {
    padding: var(--space-2) var(--space-4);
    font-size: 0.9rem;
    min-width: 80px;
  }

  .leaderboard-header,
  .leaderboard-row {
    grid-template-columns: 80px 1fr 100px 100px 100px;
    gap: var(--space-3);
    padding: var(--space-3);
    font-size: 0.95rem;
  }

  .user-avatar {
    width: 36px;
    height: 36px;
    font-size: 0.9rem;
  }

  .demo-main {
    margin-top: 90px;
  }

  .dashboard-header h1 {
    font-size: clamp(2rem, 4vw, 2.75rem);
  }

  .dashboard-header p {
    font-size: 1.1rem;
  }

  .company-grid {
    grid-template-columns: repeat(4, 1fr);
    gap: var(--space-3);
  }

  .courses-banner {
    padding: var(--space-5);
  }

  .courses-content {
    gap: var(--space-4);
  }

  .courses-icon {
    font-size: 3rem;
  }
}

/* Mobile Styles (max-width: 768px) */
@media (max-width: 768px) {
  .nav-menu {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-1);
    font-size: 0.875rem;
    order: 3;
    width: 100%;
    justify-content: center;
    margin-top: var(--space-2);
    padding-top: var(--space-2);
    border-top: 1px solid var(--surface-light);
  }

  .nav-container {
    padding: 0 var(--space-2);
    flex-wrap: wrap;
    gap: var(--space-2);
  }

  .nav-brand {
    order: 1;
  }

  .nav-actions {
    order: 2;
  }

  .footer__content {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .footer__links {
    flex-wrap: wrap;
    justify-content: center;
  }

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

  .challenges-grid,
  .projects-grid,
  .interview-categories,
  .community-features {
    grid-template-columns: 1fr;
  }

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

  .challenge-meta,
  .project-meta,
  .category-stats,
  .community-stats {
    flex-direction: row;
    justify-content: center;
    gap: var(--space-2);
    text-align: center;
    font-size: 0.75rem;
    flex-wrap: wrap;
  }

  .leaderboard-header,
  .leaderboard-row {
    grid-template-columns: 50px 1fr 70px 60px 60px;
    font-size: 0.875rem;
    gap: var(--space-1);
  }

  .user-info {
    gap: var(--space-1);
  }

  .user-info span {
    font-size: 0.875rem;
  }

  .rank {
    font-size: 0.875rem;
  }

  .challenges-filter {
    justify-content: center;
    overflow-x: auto;
    padding: var(--space-3) var(--space-2) var(--space-2) var(--space-2);
    gap: var(--space-2);
    margin-bottom: var(--space-4);
    margin-top: var(--space-4);
  }

  .filter-btn {
    white-space: nowrap;
    flex-shrink: 0;
    padding: var(--space-2) var(--space-3);
    font-size: 0.85rem;
    border-radius: var(--radius);
    border: 1px solid transparent;
    box-shadow: none;
    min-width: 60px;
  }

  .filter-btn:hover,
  .filter-btn.active {
    transform: none;
    box-shadow: none;
    border: 1px solid var(--primary);
  }

  .course-features {
    grid-template-columns: repeat(2, 1fr);
  }

  .notice-card {
    padding: var(--space-4);
  }

  .notice-icon {
    font-size: 3rem;
  }

  .company-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-2);
  }

  .company-card {
    padding: var(--space-2);
  }

  .company-card h4 {
    font-size: 0.875rem;
  }

  .company-card p {
    font-size: 0.75rem;
  }
}

@media (max-width: 480px) {
  .modal {
    width: 95%;
  }

  .navbar {
    padding: var(--space-1) 0;
  }

  .nav-menu {
    gap: var(--space-1);
    font-size: 0.75rem;
  }

  .nav-link {
    padding: var(--space-1);
  }

  /* VERY SMALL MOBILE  */
  .challenges-grid,
  .projects-grid,
  .interview-categories,
  .community-features {
    grid-template-columns: 1fr;
  }

  .btn {
    font-size: 0.75rem;
    padding: var(--space-1) var(--space-2);
  }

  .challenges-filter {
    gap: 6px;
    margin-bottom: var(--space-3);
  }

  .filter-btn {
    padding: 6px var(--space-1);
    font-size: 0.75rem;
    border-radius: 4px;
    border: 1px solid transparent;
    box-shadow: none;
  }

  .filter-btn:hover,
  .filter-btn.active {
    transform: none;
    box-shadow: none;
    border: 1px solid var(--primary);
  }

  .leaderboard-header,
  .leaderboard-row {
    grid-template-columns: 40px 1fr 50px 50px 50px;
    padding: var(--space-1);
    font-size: 0.75rem;
    gap: 4px;
  }

  .user-avatar {
    width: 20px;
    height: 20px;
    font-size: 0.625rem;
  }

  .user-info span {
    font-size: 0.75rem;
  }

  .rank {
    font-size: 0.75rem;
  }

  .course-features {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-2);
  }

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

  .notice-card .btn {
    font-size: 1rem;
    padding: var(--space-2) var(--space-4);
  }

  .company-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-1);
  }
}

/* ===== FOOTER ===== */
.footer {
  background: var(--surface);
  padding: var(--space-6) 0 var(--space-4);
  margin-top: var(--space-8);
  border-top: 1px solid var(--surface-light);
}

.footer__content {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
  margin-bottom: var(--space-4);
}

.footer__brand {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-weight: 600;
  color: var(--text-primary);
  justify-content: center;
}

.footer__logo {
  flex-shrink: 0;
}

.footer__links {
  display: flex;
  gap: var(--space-4);
  justify-content: center;
  flex-wrap: wrap;
}

.footer__links a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.9rem;
  transition: color var(--duration-normal) var(--transition);
}

.footer__links a:hover,
.footer__links a:focus {
  color: var(--primary);
}

.footer__social {
  display: flex;
  gap: var(--space-3);
  justify-content: center;
}

.footer__social a {
  color: var(--text-muted);
  transition: all var(--duration-normal) var(--transition);
  padding: var(--space-2);
  border-radius: var(--radius);
  background: var(--surface-light);
}

.footer__social a:hover,
.footer__social a:focus {
  color: var(--primary);
  background: var(--surface-lighter);
  transform: translateY(-2px);
}

.footer__bottom {
  text-align: center;
  padding-top: var(--space-4);
  border-top: 1px solid var(--surface-light);
}

.footer__bottom p {
  margin: 0 0 var(--space-1) 0;
  font-size: 0.875rem;
  color: var(--text-dim);
}

.developer-credit {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.developer-name {
  color: var(--primary);
  font-weight: 600;
}

.developer-name a {
  color: var(--primary);
  text-decoration: none;
  font-weight: 600;
}

.developer-name a:hover,
.developer-name a:focus {
  color: var(--primary);
  text-decoration: none;
}

/* ===== PREMIUM PLATFORM SECTION ===== */
.premium-platform {
  background: var(--surface);
  padding: var(--space-8) 0;
  border-top: 1px solid var(--surface-light);
}

.premium-header {
  text-align: center;
  margin-bottom: var(--space-8);
}

.premium-intro {
  font-size: 1rem;
  color: var(--text-muted);
  margin-bottom: var(--space-2);
  text-transform: uppercase;
  letter-spacing: 1px;
}

.premium-branding {
  margin-bottom: var(--space-4);
}

.premium-title {
  font-family: var(--font-heading);
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 900;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: var(--space-2);
}

.premium-badge {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-1);
}

.premium-label {
  font-size: 0.875rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 1px;
}

.premium-name {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 2px;
}

.premium-date {
  font-size: 0.875rem;
  color: var(--warning);
  font-weight: 600;
  background: rgba(245, 158, 11, 0.1);
  padding: var(--space-1) var(--space-2);
  border-radius: var(--radius);
  border: 1px solid var(--warning);
}

.premium-description {
  font-size: 1.125rem;
  color: var(--text-muted);
  max-width: 800px;
  margin: 0 auto;
  line-height: 1.6;
}

.premium-features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-4);
  margin-top: var(--space-6);
}

.premium-feature {
  background: var(--surface-light);
  padding: var(--space-4);
  border-radius: var(--radius-lg);
  border: 1px solid var(--surface-lighter);
  text-align: center;
  transition: all var(--duration-normal) var(--transition);
}

.premium-feature:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary);
}

.feature-icon {
  font-size: 3rem;
  margin-bottom: var(--space-2);
}

.premium-feature h3 {
  color: var(--text-primary);
  font-size: 1.125rem;
  margin: 0;
  line-height: 1.4;
}

/* ===== COURSES SECTION ===== */
.courses-section {
  background: var(--surface);
  padding: var(--space-8) 0;
  border-top: 1px solid var(--surface-light);
}

.courses-header {
  text-align: center;
  margin-bottom: var(--space-8);
}

.courses-header h2 {
  font-family: var(--font-heading);
  font-size: clamp(2rem, 4vw, 2.5rem);
  font-weight: 700;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: var(--space-2);
}

.courses-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: var(--space-4);
}

.course-card {
  background: var(--surface-light);
  padding: var(--space-4);
  border-radius: var(--radius-lg);
  border: 1px solid var(--surface-lighter);
  transition: all var(--duration-normal) var(--transition);
  display: flex;
  flex-direction: column;
  height: 100%;
}

.course-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary);
}

.course-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-3);
}

.course-icon {
  font-size: 2.5rem;
}

.course-price {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--success);
  background: rgba(34, 197, 94, 0.1);
  padding: var(--space-1) var(--space-2);
  border-radius: var(--radius);
  border: 1px solid var(--success);
}

.course-card h3 {
  color: var(--text-primary);
  font-size: 1.25rem;
  margin-bottom: var(--space-2);
  line-height: 1.3;
}

.course-card p {
  color: var(--text-muted);
  margin-bottom: var(--space-3);
  flex-grow: 1;
}

.course-features {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  margin-bottom: var(--space-4);
}

.course-features span {
  font-size: 0.875rem;
  color: var(--text-muted);
}

.course-card .btn {
  margin-top: auto;
  width: 100%;
}

/* Responsive Design for Courses */
@media (min-width: 768px) and (max-width: 1024px) {
  .courses-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-4);
  }
}

@media (max-width: 768px) {
  .courses-grid {
    grid-template-columns: 1fr;
    gap: var(--space-3);
  }
  
  .course-price {
    font-size: 1.25rem;
  }
  
  .course-icon {
    font-size: 2rem;
  }
}

/* Mobile-first responsive design */
@media (min-width: 768px) {
  .footer__content {
    flex-direction: row;
    justify-content: space-between;
    align-items: center;
  }

  .footer__brand {
    justify-content: flex-start;
  }

  .footer__links {
    justify-content: center;
  }

  .footer__social {
    justify-content: flex-end;
  }

  .footer__bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    text-align: left;
  }
}

.courses-notice,
.notice-card,
.feature-item {
  will-change: transform;
}

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

a:focus,
button:focus,
input:focus,
select:focus,
textarea:focus,
label:focus {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

@media (pointer: coarse) {
  .btn,
  .filter-btn,
  .tab-btn,
  .nav-link,
  .modal__close,
  .company-card {
    min-height: 44px;
    min-width: 44px;
  }
}