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

:root {
  --primary-color: #3b82f6;
  --primary-dark: #2563eb;
  --secondary-color: #10b981;
  --background: #f9fafb;
  --surface: #ffffff;
  --text-primary: #111827;
  --text-secondary: #6b7280;
  --border-color: #e5e7eb;
  --error-color: #ef4444;
  --success-color: #22c55e;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background-color: var(--background);
  color: var(--text-primary);
  line-height: 1.6;
}

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

/* Header */
.header {
  background: var(--surface);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.header-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 0;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.logo-icon {
  width: 2rem;
  height: 2rem;
  color: var(--primary-color);
}

.logo h1 {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text-primary);
}

.header-stats {
  display: flex;
  gap: 2rem;
}

.stat {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.stat-label {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.stat-value {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
}

/* Main Content */
.main {
  padding: 2rem 0;
  min-height: calc(100vh - 80px);
}

/* Loading State */
.loading {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 4rem 0;
  color: var(--text-secondary);
}

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

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* Error State */
.error {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 4rem 0;
  color: var(--error-color);
}

.error-icon {
  width: 3rem;
  height: 3rem;
  margin-bottom: 1rem;
}

.retry-btn {
  margin-top: 1rem;
  padding: 0.5rem 1rem;
  background: var(--primary-color);
  color: white;
  border: none;
  border-radius: 0.375rem;
  font-size: 0.875rem;
  cursor: pointer;
  transition: background-color 0.2s;
}

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

/* Overview Cards */
.overview {
  margin-bottom: 2rem;
}

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
}

.card {
  background: var(--surface);
  border-radius: 0.75rem;
  padding: 1.5rem;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
  display: flex;
  align-items: center;
  gap: 1rem;
  transition: transform 0.2s, box-shadow 0.2s;
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.card-icon {
  width: 3rem;
  height: 3rem;
  background: var(--primary-color);
  color: white;
  border-radius: 0.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.card-icon svg {
  width: 1.5rem;
  height: 1.5rem;
}

.card-content h3 {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-bottom: 0.25rem;
}

.card-value {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text-primary);
}

.card-value.hash {
  font-family: 'Courier New', monospace;
  font-size: 1rem;
}

/* Blocks Section */
.blocks-section h2 {
  font-size: 1.5rem;
  margin-bottom: 1rem;
  color: var(--text-primary);
}

.blocks-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.block-item {
  background: var(--surface);
  border-radius: 0.5rem;
  padding: 1rem;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
  display: flex;
  align-items: center;
  gap: 1rem;
  transition: transform 0.2s, box-shadow 0.2s;
}

.block-item:hover {
  transform: translateX(4px);
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.block-item.empty {
  opacity: 0.7;
}

.block-height {
  display: flex;
  flex-direction: column;
  align-items: center;
  min-width: 80px;
}

.height {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--primary-color);
}

.tx-badge {
  margin-top: 0.25rem;
  padding: 0.125rem 0.5rem;
  background: var(--success-color);
  color: white;
  border-radius: 9999px;
  font-size: 0.75rem;
  font-weight: 500;
}

.block-details {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.block-hash,
.block-time {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.875rem;
}

.label {
  color: var(--text-secondary);
  font-weight: 500;
}

.value {
  color: var(--text-primary);
  font-family: 'Courier New', monospace;
}

/* Responsive Design */
@media (max-width: 768px) {
  .header-content {
    flex-direction: column;
    gap: 1rem;
  }
  
  .cards {
    grid-template-columns: 1fr;
  }
  
  .block-item {
    flex-direction: column;
    align-items: flex-start;
  }
  
  .block-height {
    flex-direction: row;
    width: 100%;
    justify-content: space-between;
  }
}
