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

/* Main App Container */
.app {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* Header */
.header {
  background-color: var(--bg-elevated);
  border-bottom: 1px solid var(--border-color);
  padding: var(--spacing-md) var(--spacing-lg);
  box-shadow: var(--shadow-sm);
}

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

.logo {
  font-size: var(--font-2xl);
  font-weight: var(--font-bold);
  color: var(--accent-primary);
}

.nav {
  display: flex;
  gap: var(--spacing-lg);
  align-items: center;
}

.nav-link {
  color: var(--text-secondary);
  font-weight: var(--font-medium);
  transition: color var(--transition-fast);
}

.nav-link:hover {
  color: var(--accent-primary);
}

.nav-link.active {
  color: var(--accent-primary);
}

/* Main Content */
.main {
  flex: 1;
  max-width: 1280px;
  width: 100%;
  margin: 0 auto;
  padding: var(--spacing-xl) var(--spacing-lg);
}

/* Page Header */
.page-header {
  margin-bottom: var(--spacing-xl);
}

.page-title {
  font-size: var(--font-3xl);
  font-weight: var(--font-bold);
  margin-bottom: var(--spacing-sm);
}

.page-description {
  color: var(--text-secondary);
  font-size: var(--font-lg);
}

/* Container */
.container {
  width: 100%;
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

.container-sm {
  max-width: 640px;
}

.container-md {
  max-width: 768px;
}

/* Grid */
.grid {
  display: grid;
  gap: var(--spacing-lg);
}

.grid-cols-1 {
  grid-template-columns: repeat(1, minmax(0, 1fr));
}

.grid-cols-2 {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.grid-cols-3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

/* Flex */
.flex {
  display: flex;
}

.flex-col {
  flex-direction: column;
}

.flex-row {
  flex-direction: row;
}

.items-center {
  align-items: center;
}

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

.justify-between {
  justify-content: space-between;
}

.gap-sm {
  gap: var(--spacing-sm);
}

.gap-md {
  gap: var(--spacing-md);
}

.gap-lg {
  gap: var(--spacing-lg);
}

/* Hidden */
.hidden {
  display: none !important;
}

/* Loading State */
.loading {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: var(--z-modal);
}

/* Responsive */
@media (max-width: 768px) {
  .header-content {
    flex-direction: column;
    gap: var(--spacing-md);
  }

  .nav {
    width: 100%;
    justify-content: center;
  }

  .grid-cols-2,
  .grid-cols-3 {
    grid-template-columns: repeat(1, minmax(0, 1fr));
  }

  .main {
    padding: var(--spacing-lg) var(--spacing-md);
  }
}