:root {
  --bg-light: #e0f2fe; 
  --bg-dark: #0f172a; 
  --card-light: #ffffff;
  --card-dark: #1e293b;
  --primary: #2563eb; /* blue-600 */
  --primary-light: #3b82f6; /* blue-500 */
  --text-light: #113178;
  --text-dark: #f1f5f9; 
  --muted-light: #6b7280;
  --muted-dark: #9ca3af;
  --border-light: #e5e7eb;
  --border-dark: #334155;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif;
  background: var(--bg-light);
  color: var(--text-light);
  transition: background 0.3s ease, color 0.3s ease;
}

body.dark {
  background: var(--bg-dark);
  color: var(--text-dark);
}

/* Container centers content and constrains width */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1rem;
}

/* Header styling */
.header {
  text-align: center;
  margin: 2rem 0 1rem;
}
.header h1 {
  margin: 0;
  font-size: 2.5rem;
  font-weight: 700;
}
.header p {
  margin-top: 0.5rem;
  font-size: 1.1rem;
  color: var(--muted-light);
}
body.dark .header p {
  color: var(--muted-dark);
}

/* Theme toggle placement */
.theme-toggle {
  position: absolute;
  top: 1rem;
  right: 1rem;
}
.theme-toggle button {
  background: var(--card-light);
  color: var(--text-light);
  border: 1px solid var(--border-light);
  border-radius: 50%;
  padding: 0.5rem 0.6rem;
  cursor: pointer;
  transition: background 0.2s, color 0.2s;
}
body.dark .theme-toggle button {
  background: var(--card-dark);
  color: var(--text-dark);
  border-color: var(--border-dark);
}

/* Modal styles for username prompt */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
}
.modal {
  background: var(--card-light);
  color: var(--text-light);
  padding: 2rem;
  border-radius: 8px;
  width: 320px;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.1);
}
body.dark .modal {
  background: var(--card-dark);
  color: var(--text-dark);
}
.modal input {
  width: 100%;
  padding: 0.5rem;
  margin-bottom: 1rem;
  border: 1px solid var(--border-light);
  border-radius: 4px;
  box-sizing: border-box;
}
body.dark .modal input {
  border-color: var(--border-dark);
  background: var(--card-dark);
  color: var(--text-dark);
}
.modal button {
  width: 100%;
  padding: 0.5rem;
  background: var(--primary);
  color: #ffffff;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  transition: opacity 0.2s;
}
.modal button:disabled {
  opacity: 0.5;
  cursor: default;
}

/* Grid layout for main content */
.grid {
  display: grid;
  grid-template-columns: 100%;
  gap: 1.5rem;
}
@media (min-width: 1024px) {
  .grid {
    grid-template-columns: 70% 30%;
  }
}

/* Card component */
.card {
  background: var(--card-light);
  border: 1px solid var(--border-light);
  border-radius: 8px;
  padding: 1rem;
  display: flex;
  flex-direction: column;
}
body.dark .card {
  background: var(--card-dark);
  border-color: var(--border-dark);
}
.card h2 {
  margin-top: 0;
  margin-bottom: 0.5rem;
  font-size: 1.1rem;
  font-weight: 600;
}

/* Textarea styling */
.textarea {
  width: 100%;
  min-height: 300px;
  padding: 0.5rem;
  border: 1px solid var(--border-light);
  border-radius: 4px;
  font-family: monospace;
  font-size: 0.9rem;
  resize: vertical;
  box-sizing: border-box;
}
body.dark .textarea {
  background: var(--card-dark);
  border-color: var(--border-dark);
  color: var(--text-dark);
}

/* Action bar below textarea */
.actions {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 0.5rem;
}
.actions .left {
  color: var(--muted-light);
  font-size: 0.85rem;
}
body.dark .actions .left {
  color: var(--muted-dark);
}
.actions .right {
  display: flex;
  gap: 0.5rem;
}

/* Button styles */
.button {
  padding: 0.4rem 0.8rem;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  transition: opacity 0.2s, transform 0.1s;
}
.button.primary {
  background: var(--primary);
  color: #ffffff;
}
.button.secondary {
  background: var(--card-light);
  color: var(--text-light);
  border: 1px solid var(--border-light);
}
body.dark .button.secondary {
  background: var(--card-dark);
  color: var(--text-dark);
  border-color: var(--border-dark);
}
.button:disabled {
  opacity: 0.5;
  cursor: default;
}
.button:active {
  transform: scale(0.97);
}

/* Placeholder card for the right panel */
.placeholder {
  height: 100%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
}
.placeholder-icon {
  font-size: 3rem;
  color: var(--muted-light);
  margin-bottom: 0.5rem;
}
body.dark .placeholder-icon {
  color: var(--muted-dark);
}
.placeholder h3 {
  margin: 0;
  font-size: 1.1rem;
  color: var(--muted-light);
}
body.dark .placeholder h3 {
  color: var(--muted-dark);
}
.placeholder p {
  margin: 0;
  font-size: 0.85rem;
  color: var(--muted-light);
}
body.dark .placeholder p {
  color: var(--muted-dark);
}

/* Analytics overlay */
.analytics-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 50;
}
.analytics-panel {
  background: var(--card-light);
  color: var(--text-light);
  border: 1px solid var(--border-light);
  border-radius: 8px;
  max-width: 1000px;
  max-height: 90vh;
  width: 90%;
  overflow-y: auto;
  padding: 1rem;
  box-sizing: border-box;
}
body.dark .analytics-panel {
  background: var(--card-dark);
  color: var(--text-dark);
  border-color: var(--border-dark);
}
.analytics-panel h2 {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 0;
  margin-bottom: 1rem;
  font-size: 1.3rem;
  font-weight: 600;
}
.analytics-panel h2 button {
  background: none;
  border: none;
  font-size: 1.2rem;
  cursor: pointer;
  color: inherit;
}

/* Metrics grid */
.metrics-grid {
  display: grid;
  gap: 1rem;
  margin-bottom: 1rem;
}
@media (min-width: 640px) {
  .metrics-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}
@media (min-width: 1024px) {
  .metrics-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}
.metric-card {
  background: var(--card-light);
  border: 1px solid var(--border-light);
  border-radius: 6px;
  padding: 0.8rem;
}
body.dark .metric-card {
  background: var(--card-dark);
  border-color: var(--border-dark);
}
.metric-card .label {
  font-size: 0.85rem;
  color: var(--muted-light);
}
body.dark .metric-card .label {
  color: var(--muted-dark);
}
.metric-card .value {
  font-size: 1.5rem;
  font-weight: 600;
  margin-top: 0.2rem;
}
.metric-card .extra {
  font-size: 0.7rem;
  color: var(--muted-light);
  margin-top: 0.2rem;
}
body.dark .metric-card .extra {
  color: var(--muted-dark);
}

/* Focus keyword and suggestions */
.focus-keyword, .suggestions {
  margin-top: 1rem;
}
.focus-keyword h3, .suggestions h3 {
  margin: 0 0 0.5rem;
  font-size: 1rem;
  font-weight: 600;
}
.focus-keyword ul, .suggestions ul {
  padding-left: 1.2rem;
  margin: 0;
}
.focus-keyword li, .suggestions li {
  margin-bottom: 0.4rem;
  font-size: 0.85rem;
}