/* Excel → Markdown 樣式
 * 設計原則:
 *  - 單頁式 layout, drag-drop 上傳區佔主要視覺焦點
 *  - 上傳後 split preview (左 HTML table, 右 Markdown code)
 *  - 深淺色適配 (prefers-color-scheme)
 *  - 零外部字型, 純 system font stack
 */

:root {
  --color-bg: #ffffff;
  --color-bg-soft: #f5f5f7;
  --color-fg: #1d1d1f;
  --color-fg-soft: #6e6e73;
  --color-border: #d2d2d7;
  --color-primary: #0a84ff;
  --color-primary-fg: #ffffff;
  --color-success: #22c55e;
  --color-warning: #f59e0b;
  --color-danger: #ef4444;
  --color-card: #ffffff;
  --color-card-hover: #f5f5f7;
  --color-code-bg: #1c1c1e;
  --color-code-fg: #f5f5f7;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
  --radius: 8px;
  --radius-sm: 4px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #1c1c1e;
    --color-bg-soft: #2c2c2e;
    --color-fg: #f5f5f7;
    --color-fg-soft: #98989d;
    --color-border: #3a3a3c;
    --color-card: #2c2c2e;
    --color-card-hover: #3a3a3c;
    --color-code-bg: #0f172a;
  }
}

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

html, body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang HK", "Microsoft JhengHei", sans-serif;
  font-size: 14px;
  line-height: 1.5;
  color: var(--color-fg);
  background: var(--color-bg);
  min-height: 100vh;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px 16px;
}

/* ==================== Header ==================== */
.site-header {
  background: linear-gradient(135deg, #1e40af, #1e3a8a);
  color: #fff;
  padding: 32px 0 24px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.site-header h1 {
  font-size: 24px;
  font-weight: 700;
  margin-bottom: 4px;
}

.subtitle {
  font-size: 13px;
  opacity: 0.9;
}

/* ==================== Cards ==================== */
.card {
  background: var(--color-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 16px;
  box-shadow: var(--shadow-sm);
}

.card h2 {
  font-size: 16px;
  margin-bottom: 12px;
  color: var(--color-fg);
}

/* ==================== Drop zone ==================== */
.drop-zone {
  border: 2px dashed var(--color-border);
  border-radius: var(--radius);
  padding: 48px 16px;
  text-align: center;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s;
  background: var(--color-bg-soft);
}

.drop-zone:hover,
.drop-zone.dragging {
  background: var(--color-card-hover);
  border-color: var(--color-primary);
}

.drop-icon {
  font-size: 48px;
  margin-bottom: 12px;
  opacity: 0.6;
}

.drop-text {
  font-size: 15px;
  margin-bottom: 8px;
}

.drop-hint {
  font-size: 12px;
  color: var(--color-fg-soft);
}

.link-btn {
  background: none;
  border: none;
  color: var(--color-primary);
  text-decoration: underline;
  cursor: pointer;
  font-size: inherit;
  font-family: inherit;
  padding: 0;
}

.link-btn:hover {
  text-decoration: none;
}

/* ==================== File info ==================== */
.file-info {
  margin-top: 12px;
  padding: 10px 14px;
  background: var(--color-bg-soft);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: 13px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.file-meta {
  color: var(--color-fg-soft);
  font-size: 12px;
}

/* ==================== Sheet tabs ==================== */
.sheet-tabs {
  display: flex;
  gap: 4px;
  margin-bottom: 12px;
  padding: 4px;
  background: var(--color-bg-soft);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow-x: auto;
  flex-wrap: wrap;
}

.sheet-tab {
  padding: 6px 14px;
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-fg-soft);
  font-family: inherit;
  font-size: 13px;
  cursor: pointer;
  white-space: nowrap;
  transition: background 0.1s, color 0.1s;
}

.sheet-tab:hover {
  background: var(--color-card-hover);
  color: var(--color-fg);
}

.sheet-tab.active {
  background: var(--color-card);
  color: var(--color-primary);
  border-color: var(--color-primary);
  font-weight: 500;
}

/* ==================== Options ==================== */
.options {
  padding: 12px 20px;
}

.options-row {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.options-row label {
  font-size: 13px;
  color: var(--color-fg-soft);
}

.options-row select {
  padding: 4px 8px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-card);
  color: var(--color-fg);
  font-family: inherit;
  font-size: 13px;
  cursor: pointer;
}

.hint {
  font-size: 12px;
  color: var(--color-fg-soft);
}

/* ==================== Result / Preview ==================== */
.preview-split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-bottom: 16px;
}

@media (max-width: 768px) {
  .preview-split { grid-template-columns: 1fr; }
}

.preview-pane h3 {
  font-size: 13px;
  font-weight: 500;
  color: var(--color-fg-soft);
  margin-bottom: 8px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.preview-body {
  max-height: 480px;
  overflow: auto;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-bg-soft);
  padding: 8px;
}

.empty-hint {
  color: var(--color-fg-soft);
  text-align: center;
  padding: 32px 16px;
  font-size: 13px;
}

.preview-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 12px;
}

.preview-table th,
.preview-table td {
  border: 1px solid var(--color-border);
  padding: 4px 8px;
  text-align: left;
  white-space: nowrap;
  max-width: 240px;
  overflow: hidden;
  text-overflow: ellipsis;
}

.preview-table th {
  background: var(--color-card);
  font-weight: 600;
  position: sticky;
  top: 0;
  z-index: 1;
}

.preview-table tr:nth-child(even) td {
  background: var(--color-card);
}

.md-output {
  width: 100%;
  height: 480px;
  padding: 8px 10px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-code-bg);
  color: var(--color-code-fg);
  font-family: "SF Mono", Menlo, "Courier New", monospace;
  font-size: 12px;
  line-height: 1.5;
  resize: vertical;
  white-space: pre;
  overflow: auto;
}

.md-output:focus {
  outline: 2px solid var(--color-primary);
  outline-offset: -2px;
}

/* ==================== Actions ==================== */
.actions {
  display: flex;
  gap: 8px;
  justify-content: flex-end;
  flex-wrap: wrap;
}

.btn-primary,
.btn-secondary,
.btn-tertiary {
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  font-family: inherit;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  border: 1px solid transparent;
  transition: background 0.1s, border-color 0.1s;
}

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

.btn-primary:hover {
  filter: brightness(1.1);
}

.btn-secondary {
  background: var(--color-card);
  color: var(--color-fg);
  border-color: var(--color-border);
}

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

.btn-tertiary {
  background: transparent;
  color: var(--color-fg-soft);
  border-color: transparent;
}

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

/* ==================== Loading & Error ==================== */
.loading {
  text-align: center;
  padding: 16px;
  color: var(--color-fg-soft);
  font-size: 13px;
}

.loading::before {
  content: "⏳ ";
}

.error-msg {
  padding: 12px 16px;
  background: rgba(239, 68, 68, 0.1);
  border: 1px solid var(--color-danger);
  border-radius: var(--radius-sm);
  color: var(--color-danger);
  font-size: 13px;
  margin-top: 12px;
}

/* ==================== Toast ==================== */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  padding: 10px 20px;
  background: var(--color-fg);
  color: var(--color-bg);
  border-radius: 999px;
  font-size: 13px;
  font-weight: 500;
  box-shadow: var(--shadow-md);
  z-index: 1000;
  animation: toastIn 0.2s ease;
}

@keyframes toastIn {
  from { opacity: 0; transform: translateX(-50%) translateY(8px); }
  to { opacity: 1; transform: translateX(-50%) translateY(0); }
}

/* ==================== Footer ==================== */
.site-footer {
  margin-top: 40px;
  padding: 20px 0;
  border-top: 1px solid var(--color-border);
  text-align: center;
  font-size: 12px;
  color: var(--color-fg-soft);
}

.site-footer p {
  margin: 4px 0;
}

.site-footer a {
  color: var(--color-primary);
  text-decoration: none;
}

.site-footer a:hover {
  text-decoration: underline;
}

.muted {
  opacity: 0.7;
}

[hidden] {
  display: none !important;
}

/* .hidden class — 透過 JS classList 切換 (e.g. loading, file-info, sheet-tabs) */
.hidden {
  display: none !important;
}