:root {
  --primary-color: #3b82f6;
  --primary-dark: #1e40af;
  --secondary-color: #8b5cf6;
  --accent-color: #06b6d4;
  --success-color: #10b981;
  --warning-color: #f59e0b;
  --danger-color: #ef4444;
  --dark-color: #1f2937;
  --gray-50: #f9fafb;
  --gray-100: #f3f4f6;
  --gray-200: #e5e7eb;
  --gray-300: #d1d5db;
  --gray-400: #9ca3af;
  --gray-500: #6b7280;
  --gray-600: #4b5563;
  --gray-700: #374151;
  --gray-800: #1f2937;
  --gray-900: #111827;
  --white: #ffffff;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1),
    0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1),
    0 8px 10px -6px rgb(0 0 0 / 0.1);
  --border-radius: 0.75rem;
  --border-radius-lg: 1rem;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
  line-height: 1.6;
  color: var(--gray-800);
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  min-height: 100vh;
  overflow-x: hidden;
}

.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 2rem 1rem;
}

/* Navbar */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  z-index: 100;
  padding: 1rem 0;
  transition: var(--transition);
}

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

.nav-content {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 1rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--gray-800);
  text-decoration: none;
}

.nav-logo {
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 0.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  background: white;
  padding: 0.25rem;
  box-shadow: var(--shadow-sm);
}

.nav-logo img {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

.nav-links {
  display: flex;
  gap: 2rem;
  list-style: none;
}

.nav-links a {
  color: var(--gray-600);
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition);
  position: relative;
}

.nav-links a:hover {
  color: var(--primary-color);
}

.nav-links a::after {
  content: "";
  position: absolute;
  bottom: -0.25rem;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--primary-color);
  transition: var(--transition);
}

.nav-links a:hover::after {
  width: 100%;
}

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--gray-600);
  cursor: pointer;
}

/* Hero Section */
.hero {
  margin-top: 5rem;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-radius: var(--border-radius-lg);
  padding: 3rem;
  margin-bottom: 2rem;
  box-shadow: var(--shadow-xl);
  border: 1px solid rgba(255, 255, 255, 0.2);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(
    90deg,
    var(--primary-color),
    var(--secondary-color),
    var(--accent-color)
  );
}

.hero-content {
  text-align: center;
  max-width: 800px;
  margin: 0 auto;
}

.university-logo {
  width: 100px;
  height: 100px;
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  border-radius: 50%;
  margin: 0 auto 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 2rem;
  box-shadow: var(--shadow-lg);
}

.hero h1 {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 800;
  color: var(--gray-900);
  margin-bottom: 1rem;
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.25rem;
  color: var(--gray-600);
  margin-bottom: 0.5rem;
}

.hero .academic-year {
  font-size: 1rem;
  color: var(--gray-500);
  font-weight: 500;
}

/* Stats Section */
.stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}

.stat-card {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-radius: var(--border-radius);
  padding: 2rem;
  text-align: center;
  box-shadow: var(--shadow-md);
  border: 1px solid rgba(255, 255, 255, 0.2);
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.stat-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--primary-color);
  transform: scaleX(0);
  transition: var(--transition);
}

.stat-card:hover::before {
  transform: scaleX(1);
}

.stat-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.stat-icon {
  width: 3rem;
  height: 3rem;
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  border-radius: 50%;
  margin: 0 auto 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 1.25rem;
}

.stat-number {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--gray-900);
  display: block;
  margin-bottom: 0.5rem;
}

.stat-label {
  color: var(--gray-600);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-size: 0.875rem;
}

/* Main Content */
.main-content {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-radius: var(--border-radius-lg);
  padding: 2.5rem;
  box-shadow: var(--shadow-xl);
  border: 1px solid rgba(255, 255, 255, 0.2);
}

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

.section-title {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--gray-900);
  margin-bottom: 1rem;
  position: relative;
}

.section-subtitle {
  font-size: 1.125rem;
  color: var(--gray-600);
  max-width: 600px;
  margin: 0 auto;
}

/* Filter and Search */
.controls {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
  gap: 1rem;
  flex-wrap: wrap;
}

.search-box {
  display: flex;
  align-items: center;
  background: white;
  border: 2px solid var(--gray-200);
  border-radius: var(--border-radius);
  padding: 0.75rem 1rem;
  min-width: 300px;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.search-box:focus-within {
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.search-box input {
  border: none;
  outline: none;
  flex: 1;
  font-size: 1rem;
  margin-left: 0.75rem;
}

.filter-buttons {
  display: flex;
  gap: 0.5rem;
}

.filter-btn {
  padding: 0.75rem 1.5rem;
  border: 2px solid var(--gray-300);
  background: white;
  border-radius: var(--border-radius);
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
}

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

/* Assignment Grid */
.assignments-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: 2rem;
}

.assignment-card {
  background: white;
  border-radius: var(--border-radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-md);
  transition: var(--transition);
  border: 1px solid var(--gray-200);
  position: relative;
}

.assignment-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(
    90deg,
    var(--primary-color),
    var(--secondary-color)
  );
}

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

.card-header {
  padding: 2rem 2rem 1rem;
  position: relative;
}

/* Lecturer Section */
.lecturer-section {
  margin: 2rem 0;
}

.lecturer-card {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-radius: var(--border-radius-lg);
  padding: 2rem;
  box-shadow: var(--shadow-xl);
  border: 1px solid rgba(255, 255, 255, 0.2);
  position: relative;
  overflow: hidden;
}

.lecturer-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(
    90deg,
    var(--primary-color),
    var(--secondary-color),
    var(--accent-color)
  );
}

.lecturer-content {
  display: flex;
  align-items: center;
  gap: 2rem;
  flex-wrap: wrap;
}

.lecturer-avatar {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  overflow: hidden;
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-lg);
  flex-shrink: 0;
}

.lecturer-photo {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.lecturer-fallback {
  display: none;
  color: white;
  font-size: 2.5rem;
}

.lecturer-info {
  flex: 1;
  min-width: 300px;
}

.lecturer-name {
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--gray-900);
  margin-bottom: 0.5rem;
}

.lecturer-title {
  font-size: 1.1rem;
  color: var(--primary-color);
  font-weight: 600;
  margin-bottom: 0.25rem;
}

.lecturer-department {
  color: var(--gray-600);
  margin-bottom: 1rem;
  font-style: italic;
}

.lecturer-description {
  color: var(--gray-700);
  line-height: 1.6;
  margin-bottom: 1.5rem;
}

.lecturer-contact {
  margin-top: 1rem;
}

.contact-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  color: white;
  padding: 0.75rem 1.5rem;
  border-radius: var(--border-radius);
  text-decoration: none;
  font-weight: 600;
  transition: var(--transition);
  box-shadow: var(--shadow-md);
}

.contact-btn:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

/* Responsive Design for Lecturer Section */
@media (max-width: 768px) {
  .lecturer-content {
    flex-direction: column;
    text-align: center;
  }

  .lecturer-info {
    min-width: auto;
  }
}

.student-avatar {
  width: 4rem;
  height: 4rem;
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 1rem;
  position: relative;
}

.status-indicator {
  position: absolute;
  bottom: -2px;
  right: -2px;
  width: 1rem;
  height: 1rem;
  border-radius: 50%;
  border: 2px solid white;
}

.student-matric {
  font-size: 0.9rem;
  color: #555;
  margin-top: -4px;
  margin-bottom: 6px;
}

.status-completed {
  background: var(--success-color);
}

.status-pending {
  background: var(--warning-color);
}

.student-name {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--gray-900);
  margin-bottom: 0.5rem;
}

.assignment-title {
  color: var(--gray-600);
  font-size: 1rem;
  margin-bottom: 1rem;
}

.card-meta {
  display: flex;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.meta-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--gray-500);
  font-size: 0.875rem;
}

.card-actions {
  padding: 0 2rem 2rem;
  display: flex;
  gap: 1rem;
}

.btn {
  padding: 0.75rem 1.5rem;
  border-radius: var(--border-radius);
  font-weight: 600;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  transition: var(--transition);
  border: none;
  cursor: pointer;
  font-size: 0.875rem;
}

.btn-primary {
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--primary-dark)
  );
  color: white;
  flex: 1;
  justify-content: center;
}

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

.btn-secondary {
  background: var(--gray-100);
  color: var(--gray-700);
  border: 1px solid var(--gray-300);
}

.btn-secondary:hover {
  background: var(--gray-200);
}

.student-photo {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 50%;
}

.avatar-fallback {
  display: none;
  color: white;
  font-size: 1.5rem;
  font-weight: 700;
}

/* Footer */
.footer {
  margin-top: 4rem;
  padding: 2rem 0;
  text-align: center;
  color: rgba(255, 255, 255, 0.9);
}

.footer-content {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 2rem;
  flex-wrap: wrap;
  margin-bottom: 1rem;
}

.footer-logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  color: white;
  font-weight: 700;
}

.footer-links {
  display: flex;
  gap: 2rem;
  list-style: none;
}

.footer-links a {
  color: rgba(255, 255, 255, 0.8);
  text-decoration: none;
  font-size: 0.875rem;
  transition: var(--transition);
}

.footer-links a:hover {
  color: white;
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: 1rem;
  font-size: 0.875rem;
  color: rgba(255, 255, 255, 0.7);
}

/* Loading Animation */
.loading {
  display: none;
  justify-content: center;
  align-items: center;
  padding: 3rem;
}

.spinner {
  width: 3rem;
  height: 3rem;
  border: 4px solid var(--gray-200);
  border-top: 4px solid var(--primary-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}

/* Responsive Design */
@media (max-width: 768px) {
  .nav-links {
    display: none;
  }

  .mobile-menu-btn {
    display: block;
  }

  .container {
    padding: 1rem;
  }

  .hero {
    margin-top: 4rem;
    padding: 2rem;
  }

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

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

  .controls {
    flex-direction: column;
    align-items: stretch;
  }

  .search-box {
    min-width: auto;
  }

  .filter-buttons {
    justify-content: center;
    flex-wrap: wrap;
  }

  .section-title {
    font-size: 2rem;
  }
}

@media (max-width: 480px) {
  .hero h1 {
    font-size: 1.75rem;
  }

  .assignments-grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }

  .assignment-card {
    margin: 0;
  }
}

/* Animation Classes */
.fade-in {
  animation: fadeIn 0.8s ease-out forwards;
}

.slide-up {
  animation: slideUp 0.8s ease-out forwards;
}

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

@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}