:root,
[data-theme="light"] {
  --bg: #f9fafb;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f3f4f6;
  --text: #111827;
  --text-secondary: #6b7280;
  --border: #e5e7eb;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --success: #059669;
  --danger: #dc2626;
}

[data-theme="dark"] {
  --bg: #111827;
  --bg-secondary: #1f2937;
  --bg-tertiary: #374151;
  --text: #f9fafb;
  --text-secondary: #9ca3af;
  --border: #374151;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --success: #10b981;
  --danger: #ef4444;
}

[data-theme="sepia"] {
  --bg: #f5f0e8;
  --bg-secondary: #fdf8f0;
  --bg-tertiary: #ede5d8;
  --text: #5c4b37;
  --text-secondary: #8a7a66;
  --border: #d4c5af;
  --accent: #b8860b;
  --accent-hover: #996f09;
  --success: #6b8e23;
  --danger: #c0392b;
}

[data-theme="ocean"] {
  --bg: #f0f7fa;
  --bg-secondary: #ffffff;
  --bg-tertiary: #e0f0f5;
  --text: #1a3a4a;
  --text-secondary: #5a8a9a;
  --border: #b0d0e0;
  --accent: #0077b6;
  --accent-hover: #005f8a;
  --success: #2a9d8f;
  --danger: #e63946;
}

[data-theme="rose"] {
  --bg: #fdf2f4;
  --bg-secondary: #ffffff;
  --bg-tertiary: #fce4ec;
  --text: #4a1a2a;
  --text-secondary: #8a5a6a;
  --border: #e8b0c0;
  --accent: #e91e63;
  --accent-hover: #c2185b;
  --success: #4caf50;
  --danger: #d32f2f;
}

[data-theme="mint"] {
  --bg: #f0faf5;
  --bg-secondary: #ffffff;
  --bg-tertiary: #e0f5ea;
  --text: #1a3a2a;
  --text-secondary: #5a8a6a;
  --border: #b0e0c8;
  --accent: #00c853;
  --accent-hover: #00a844;
  --success: #2e7d32;
  --danger: #c62828;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
.hidden { display: none !important; }
body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  height: 100vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 16px;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border);
  z-index: 100;
  flex-shrink: 0;
}

.header-left {
  display: flex;
  align-items: center;
  gap: 12px;
}

.header-left a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 14px;
  padding: 6px 10px;
  border-radius: 8px;
  transition: background 0.15s;
}

.header-left a:hover {
  background: var(--bg-tertiary);
  color: var(--text);
}

.header-left h1 {
  font-size: 18px;
  font-weight: 700;
}

.header-right {
  display: flex;
  align-items: center;
  gap: 8px;
}

.btn {
  padding: 6px 14px;
  border-radius: 8px;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  border: 1px solid var(--border);
  background: var(--bg-secondary);
  color: var(--text);
  transition: background 0.15s, color 0.15s;
}

.btn:hover {
  background: var(--bg-tertiary);
}

.btn-primary {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

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

.btn-success {
  background: var(--success);
  color: #fff;
  border-color: var(--success);
}

.theme-select {
  padding: 6px 10px;
  border-radius: 8px;
  font-size: 13px;
  border: 1px solid var(--border);
  background: var(--bg-secondary);
  color: var(--text);
  cursor: pointer;
}

.main-layout {
  display: flex;
  flex: 1;
  overflow: hidden;
}

#sheet-container {
  flex: 1;
  overflow: hidden;
  min-width: 0;
}

.ai-panel {
  width: 360px;
  background: var(--bg-secondary);
  border-left: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  flex-shrink: 0;
}

.ai-panel.hidden {
  display: none;
}

.ai-panel-header {
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-shrink: 0;
}

.ai-panel-header h2 {
  font-size: 15px;
  font-weight: 600;
}

.ai-tabs {
  display: flex;
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.ai-tab {
  flex: 1;
  padding: 10px 8px;
  text-align: center;
  font-size: 12px;
  font-weight: 500;
  color: var(--text-secondary);
  background: none;
  border: none;
  cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: color 0.15s, border-color 0.15s;
}

.ai-tab:hover {
  color: var(--text);
}

.ai-tab.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

.ai-tab-content {
  flex: 1;
  overflow-y: auto;
  padding: 16px;
}

.ai-tab-content.hidden {
  display: none;
}

.ai-label {
  display: block;
  font-size: 12px;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 6px;
}

.ai-input,
.ai-textarea,
.ai-select {
  width: 100%;
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 13px;
  background: var(--bg);
  color: var(--text);
  margin-bottom: 12px;
  font-family: inherit;
}

.ai-textarea {
  resize: vertical;
  min-height: 80px;
}

.ai-input:focus,
.ai-textarea:focus,
.ai-select:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.ai-output {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px;
  font-size: 13px;
  min-height: 60px;
  white-space: pre-wrap;
  word-break: break-word;
  line-height: 1.5;
}

.ai-output:empty::before {
  content: attr(data-placeholder);
  color: var(--text-secondary);
  font-style: italic;
}

.ai-output-actions {
  display: flex;
  gap: 6px;
  margin-top: 8px;
}

.ai-output-actions .btn {
  font-size: 12px;
  padding: 5px 10px;
}

.spinner {
  display: inline-block;
  width: 14px;
  height: 14px;
  border: 2px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
}

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

[data-theme="dark"] .header,
[data-theme="dark"] .ai-panel {
  background: var(--bg-secondary);
  border-color: var(--border);
}

[data-theme="dark"] .btn,
[data-theme="dark"] .theme-select,
[data-theme="dark"] .ai-input,
[data-theme="dark"] .ai-textarea,
[data-theme="dark"] .ai-select {
  background: var(--bg-tertiary);
  color: var(--text);
  border-color: var(--border);
}

.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: center;
}
.modal-overlay.hidden { display: none; }
.modal {
  background: var(--bg-secondary);
  border-radius: 12px;
  padding: 24px;
  max-width: 400px;
  width: 90%;
  border: 1px solid var(--border);
}
.modal h3 { font-size: 16px; font-weight: 600; margin-bottom: 16px; }
.password-hint { font-size: 11px; color: var(--text-secondary); margin-top: -6px; margin-bottom: 8px; }
.password-mismatch { font-size: 11px; color: var(--danger); margin-top: 2px; }

@media (max-width: 768px) {
  .ai-panel {
    position: fixed;
    right: 0;
    top: 0;
    bottom: 0;
    z-index: 200;
    box-shadow: -4px 0 20px rgba(0,0,0,0.15);
  }
}

.toast {
  position: fixed;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--bg-secondary);
  color: var(--text);
  border: 1px solid var(--border);
  padding: 12px 24px;
  border-radius: 8px;
  z-index: 9999;
  animation: sheetToastSlide 0.3s ease-out;
}
.toast-error {
  background: #fef2f2;
  color: #dc2626;
  border-color: #fecaca;
}
[data-theme="dark"] .toast-error {
  background: #450a0a;
  color: #fca5a5;
  border-color: #7f1d1d;
}
@keyframes sheetToastSlide {
  from { opacity: 0; transform: translate(-50%, 20px); }
  to { opacity: 1; transform: translate(-50%, 0); }
}