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

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  min-height: 100vh;
}

.navbar {
  background: rgba(255, 255, 255, 0.95);
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.nav-brand {
  font-size: 1.5rem;
  font-weight: bold;
  color: #667eea;
}

.nav-links {
  display: flex;
  gap: 1.5rem;
}

.nav-links a {
  color: #333;
  text-decoration: none;
  font-weight: 500;
  transition: color 0.3s;
}

.nav-links a:hover {
  color: #667eea;
}

.hidden {
  display: none !important;
}

.container {
  max-width: 1200px;
  margin: 2rem auto;
  padding: 0 1rem;
}

.page {
  animation: fadeIn 0.3s ease-in;
}

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

.hero {
  text-align: center;
  padding: 4rem 2rem;
  color: white;
}

.hero h1 {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.hero p {
  font-size: 1.2rem;
  opacity: 0.9;
}

.auth-box {
  max-width: 400px;
  margin: 2rem auto;
  background: white;
  padding: 2rem;
  border-radius: 10px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
}

.auth-box h2 {
  text-align: center;
  margin-bottom: 1.5rem;
  color: #667eea;
}

.form-group {
  margin-bottom: 1rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.5rem;
  color: #333;
  font-weight: 500;
}

.form-group input,
.form-group select {
  width: 100%;
  padding: 0.75rem;
  border: 1px solid #ddd;
  border-radius: 5px;
  font-size: 1rem;
}

.auth-box button {
  width: 100%;
  padding: 0.75rem;
  background: #667eea;
  color: white;
  border: none;
  border-radius: 5px;
  font-size: 1rem;
  cursor: pointer;
  transition: background 0.3s;
}

.auth-box button:hover {
  background: #5568d3;
}

.auth-box p {
  text-align: center;
  margin-top: 1rem;
}

.auth-box a {
  color: #667eea;
  text-decoration: none;
  font-weight: 500;
}

.course-card,
.grade-card {
  background: white;
  padding: 1.5rem;
  margin-bottom: 1rem;
  border-radius: 10px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.course-card h3,
.grade-card h3 {
  color: #667eea;
  margin-bottom: 0.5rem;
}

.course-card p {
  color: #666;
  margin-bottom: 0.5rem;
}

.assignment-item,
.announcement-item {
  background: white;
  padding: 1rem;
  margin-bottom: 0.5rem;
  border-radius: 5px;
  border-left: 4px solid #667eea;
}

.announcement-item.pinned {
  border-left-color: #f39c12;
  background: #fff9e6;
}

.assignment-item h4,
.announcement-item strong {
  color: #333;
  margin-bottom: 0.25rem;
}

.assignment-item span,
.announcement-item p {
  color: #666;
  font-size: 0.9rem;
}

.assignment-item small {
  display: block;
  margin-top: 0.5rem;
  color: #999;
}

.back-button {
  background: white;
  border: none;
  padding: 0.5rem 1rem;
  border-radius: 5px;
  cursor: pointer;
  font-weight: 500;
  margin-bottom: 1rem;
}

.back-button:hover {
  background: #f0f0f0;
}

.details-section {
  background: white;
  padding: 1.5rem;
  margin-bottom: 1rem;
  border-radius: 10px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.details-section h3 {
  color: #667eea;
  margin-bottom: 1rem;
}

@media (max-width: 768px) {
  .navbar {
    flex-direction: column;
    gap: 1rem;
  }
  
  .nav-links {
    flex-wrap: wrap;
    justify-content: center;
  }
  
  .hero h1 {
    font-size: 2rem;
  }
}