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

:root {
  --primary-color: #2563eb;
  --primary-hover: #1d4ed8;
  --secondary-color: #10b981;
  --text-dark: #1f2937;
  --text-light: #6b7280;
  --bg-light: #f9fafb;
  --bg-white: #ffffff;
  --border-color: #e5e7eb;
  --error-color: #ef4444;
  --success-color: #10b981;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
    'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
    sans-serif;
  line-height: 1.6;
  color: var(--text-dark);
  background-color: var(--bg-light);
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.navbar {
  background-color: var(--bg-white);
  box-shadow: var(--shadow);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.navbar .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 20px;
}

.nav-brand h1 {
  color: var(--primary-color);
  font-size: 1.5rem;
}

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

.nav-menu a {
  color: var(--text-dark);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.3s;
}

.nav-menu a:hover,
.nav-menu a.active {
  color: var(--primary-color);
}

.hero {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 5rem 0;
  text-align: center;
}

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

.hero h2 {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.hero-subtitle {
  font-size: 1.5rem;
  margin-bottom: 1.5rem;
  opacity: 0.95;
}

.hero-description {
  font-size: 1.1rem;
  margin-bottom: 2rem;
  line-height: 1.8;
  opacity: 0.9;
}

.btn {
  display: inline-block;
  padding: 0.75rem 2rem;
  border-radius: 8px;
  text-decoration: none;
  font-weight: 600;
  transition: all 0.3s;
  border: none;
  cursor: pointer;
  font-size: 1rem;
}

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

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

.btn-secondary {
  background-color: white;
  color: var(--primary-color);
}

.btn-secondary:hover {
  background-color: var(--bg-light);
}

.btn-small {
  padding: 0.5rem 1rem;
  font-size: 0.9rem;
}

.btn-full {
  width: 100%;
}

.features {
  padding: 5rem 0;
  background-color: var(--bg-white);
}

.section-title {
  text-align: center;
  font-size: 2.5rem;
  margin-bottom: 3rem;
  color: var(--text-dark);
}

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

.feature-card {
  text-align: center;
  padding: 2rem;
  border-radius: 12px;
  background-color: var(--bg-light);
  transition: transform 0.3s, box-shadow 0.3s;
}

.feature-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
}

.feature-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.feature-card h3 {
  margin-bottom: 1rem;
  color: var(--text-dark);
}

.feature-card p {
  color: var(--text-light);
  line-height: 1.6;
}

.cta {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 4rem 0;
  text-align: center;
}

.cta h2 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
}

.cta p {
  font-size: 1.2rem;
  margin-bottom: 2rem;
  opacity: 0.9;
}

.footer {
  background-color: var(--text-dark);
  color: white;
  text-align: center;
  padding: 2rem 0;
}

.page-header {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 3rem 0;
  text-align: center;
}

.page-header h2 {
  font-size: 2.5rem;
  margin-bottom: 0.5rem;
}

.courses-section {
  padding: 4rem 0;
}

.loading,
.error {
  text-align: center;
  padding: 2rem;
  font-size: 1.2rem;
}

.error {
  color: var(--error-color);
}

.courses-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 2rem;
}

.course-card {
  background-color: var(--bg-white);
  border-radius: 12px;
  padding: 2rem;
  box-shadow: var(--shadow);
  transition: transform 0.3s, box-shadow 0.3s;
}

.course-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
}

.course-header {
  display: flex;
  justify-content: space-between;
  align-items: start;
  margin-bottom: 1rem;
}

.course-header h3 {
  flex: 1;
  color: var(--text-dark);
  font-size: 1.4rem;
}

.course-price {
  background-color: var(--secondary-color);
  color: white;
  padding: 0.5rem 1rem;
  border-radius: 20px;
  font-weight: 600;
  font-size: 1.1rem;
}

.course-description {
  color: var(--text-light);
  margin-bottom: 1.5rem;
  line-height: 1.6;
}

.course-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 1rem;
  border-top: 1px solid var(--border-color);
}

.course-duration {
  color: var(--text-light);
  font-size: 0.9rem;
}

.no-courses {
  text-align: center;
  color: var(--text-light);
  font-size: 1.2rem;
  padding: 3rem;
}

.contact-section {
  padding: 4rem 0;
}

.contact-content {
  display: grid;
  grid-template-columns: 1fr 1.5fr;
  gap: 3rem;
  max-width: 1000px;
  margin: 0 auto;
}

.contact-info {
  background-color: var(--bg-white);
  padding: 2rem;
  border-radius: 12px;
  box-shadow: var(--shadow);
}

.contact-info h3 {
  font-size: 1.8rem;
  margin-bottom: 1rem;
  color: var(--text-dark);
}

.contact-info p {
  color: var(--text-light);
  margin-bottom: 2rem;
  line-height: 1.6;
}

.info-item {
  margin-bottom: 1rem;
  padding: 0.75rem;
  background-color: var(--bg-light);
  border-radius: 8px;
}

.info-item strong {
  color: var(--primary-color);
}

.contact-form-wrapper {
  background-color: var(--bg-white);
  padding: 2rem;
  border-radius: 12px;
  box-shadow: var(--shadow);
}

.contact-form,
.auth-form {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.form-group label {
  font-weight: 600;
  color: var(--text-dark);
}

.form-group input,
.form-group textarea {
  padding: 0.75rem;
  border: 2px solid var(--border-color);
  border-radius: 8px;
  font-size: 1rem;
  transition: border-color 0.3s;
  font-family: inherit;
}

.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--primary-color);
}

.form-message {
  padding: 1rem;
  border-radius: 8px;
  margin-top: 1rem;
  text-align: center;
}

.form-message.success {
  background-color: #d1fae5;
  color: #065f46;
}

.form-message.error {
  background-color: #fee2e2;
  color: #991b1b;
}

.auth-section {
  padding: 4rem 0;
  min-height: calc(100vh - 400px);
  display: flex;
  align-items: center;
}

.auth-box {
  max-width: 450px;
  margin: 0 auto;
  background-color: var(--bg-white);
  padding: 3rem;
  border-radius: 12px;
  box-shadow: var(--shadow-lg);
}

.auth-box h2 {
  text-align: center;
  margin-bottom: 2rem;
  color: var(--text-dark);
}

.auth-switch {
  text-align: center;
  margin-top: 1.5rem;
  color: var(--text-light);
}

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

.auth-switch a:hover {
  text-decoration: underline;
}

@media (max-width: 768px) {
  .nav-menu {
    gap: 1rem;
  }

  .hero h2 {
    font-size: 2rem;
  }

  .hero-subtitle {
    font-size: 1.2rem;
  }

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

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

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

  .contact-content {
    grid-template-columns: 1fr;
  }

  .auth-box {
    padding: 2rem;
  }

  .page-header h2 {
    font-size: 2rem;
  }
}

@media (max-width: 480px) {
  .navbar .container {
    flex-direction: column;
    gap: 1rem;
  }

  .nav-menu {
    flex-wrap: wrap;
    justify-content: center;
    gap: 0.5rem;
  }

  .hero {
    padding: 3rem 0;
  }

  .hero h2 {
    font-size: 1.5rem;
  }

  .hero-subtitle {
    font-size: 1rem;
  }

  .hero-description {
    font-size: 0.95rem;
  }
}