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

:root {
  --primary: #4a5568;
  --primary-light: #718096;
  --secondary: #38a169;
  --secondary-light: #68d391;
  --accent: #ed8936;
  --accent-light: #fbd38d;
  --bg: #f7fafc;
  --bg-dark: #edf2f7;
  --text: #2d3748;
  --text-light: #718096;
  --border: #cbd5e0;
  --success: #38a169;
  --warning: #ed8936;
  --info: #3182ce;
  --danger: #e53e3e;
}

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

/* Navigation Bar */
.navbar {
  background: var(--primary);
  color: white;
  padding: 1rem 0;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
  position: sticky;
  top: 0;
  z-index: 100;
}

.navbar-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 2rem;
}

.navbar-title {
  font-size: 1.5rem;
  font-weight: 700;
  white-space: nowrap;
  margin-right: auto;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 1.5rem;
  flex: 1;
}

.nav-link {
  color: white;
  text-decoration: none;
  padding: 0.5rem 0;
  border-bottom: 2px solid transparent;
  transition: border-color 0.3s;
  cursor: pointer;
}

.nav-link:hover,
.nav-link.active {
  border-bottom-color: var(--secondary-light);
}

.nav-actions {
  display: flex;
  gap: 0.5rem;
}

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 2rem 1rem;
  min-height: calc(100vh - 70px);
}

/* Pages */
.page {
  display: none;
}

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

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

.page-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
  border-bottom: 2px solid var(--border);
  padding-bottom: 1rem;
}

.page-header h2 {
  font-size: 2rem;
  color: var(--primary);
}

/* Buttons */
.btn {
  background: var(--secondary);
  color: white;
  border: none;
  padding: 0.75rem 1.5rem;
  border-radius: 4px;
  cursor: pointer;
  font-size: 1rem;
  transition: background 0.3s;
  font-weight: 600;
}

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

.btn-small {
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
}

.btn-back {
  background: var(--primary-light);
  color: white;
  border: none;
  padding: 0.5rem 1rem;
  border-radius: 4px;
  cursor: pointer;
  font-size: 0.875rem;
  transition: background 0.3s;
}

.btn-back:hover {
  background: var(--primary);
}

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

.btn-primary:hover {
  background: var(--primary-light);
}

.btn-danger {
  background: var(--danger);
}

.btn-danger:hover {
  background: #c53030;
}

/* Modal */
.modal {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
}

.modal-content {
  background: white;
  border-radius: 8px;
  padding: 2rem;
  max-width: 600px;
  width: 90%;
  max-height: 80vh;
  overflow-y: auto;
  position: relative;
  box-shadow: 0 20px 60px rgba(0,0,0,0.3);
}

.modal-close {
  position: absolute;
  top: 1rem;
  right: 1rem;
  background: none;
  border: none;
  font-size: 2rem;
  cursor: pointer;
  color: var(--text-light);
  width: 2rem;
  height: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

.modal-close:hover {
  color: var(--text);
}

/* Progress Bar */
.progress-bar {
  width: 100%;
  height: 8px;
  background: var(--border);
  border-radius: 4px;
  overflow: hidden;
  margin: 0.5rem 0;
}

.progress-fill {
  height: 100%;
  background: var(--secondary);
  transition: width 0.3s ease;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 0.7rem;
  font-weight: bold;
}

/* Cards */
.card {
  background: white;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 1.5rem;
  margin-bottom: 1rem;
  transition: box-shadow 0.3s;
}

.card:hover {
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.card-title {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  color: var(--primary);
}

.card-meta {
  font-size: 0.875rem;
  color: var(--text-light);
}

/* Checkbox */
.checkbox-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin: 1rem 0;
}

.checkbox-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem;
  border-radius: 4px;
  transition: background 0.2s;
}

.checkbox-item:hover {
  background: var(--bg-dark);
}

.checkbox-item input[type="checkbox"] {
  width: 20px;
  height: 20px;
  cursor: pointer;
}

.checkbox-item label {
  flex: 1;
  cursor: pointer;
  margin: 0;
}

.checkbox-item input[type="checkbox"]:checked + label {
  color: var(--secondary);
  font-weight: 500;
}

/* List */
.list-item {
  padding: 1rem;
  border: 1px solid var(--border);
  border-radius: 4px;
  margin-bottom: 0.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  transition: all 0.2s;
}

.list-item:hover {
  background: var(--bg-dark);
  border-color: var(--secondary);
}

.list-item-title {
  font-weight: 600;
}

.list-item-meta {
  font-size: 0.875rem;
  color: var(--text-light);
}

.list-item-arrow {
  color: var(--text-light);
  font-size: 1.5rem;
}

/* Responsive */
@media (max-width: 768px) {
  .navbar-content {
    flex-direction: column;
    gap: 1rem;
  }

  .nav-links {
    flex-direction: column;
    gap: 0.5rem;
    width: 100%;
  }

  .page-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 1rem;
  }

  .container {
    padding: 1rem;
  }
}