/* ========== CSS Variables ========== */
:root {
  --color-primary: #1a73e8;
  --color-primary-hover: #1557b0;
  --color-primary-light: #e8f0fe;
  --color-bg: #f8f9fa;
  --color-white: #ffffff;
  --color-text: #202124;
  --color-text-secondary: #5f6368;
  --color-border: #dadce0;
  --color-success: #34a853;
  --color-warning: #fbbc04;
  --color-error: #ea4335;
  --color-card-shadow: rgba(0, 0, 0, 0.08);
  --font-display: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-body: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans SC', sans-serif;
  --font-mono: 'Fira Code', 'Source Code Pro', 'Consolas', monospace;
  --radius: 8px;
  --radius-lg: 12px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.1);
  --shadow-lg: 0 8px 24px rgba(0,0,0,0.12);
  --transition: 0.2s ease;
}

/* ========== Reset & Base ========== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  min-height: 100vh;
}

a { color: var(--color-primary); text-decoration: none; }
a:hover { text-decoration: underline; }

img { max-width: 100%; height: auto; }

/* ========== Layout ========== */
.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ========== Header ========== */
.site-header {
  background: var(--color-white);
  border-bottom: 1px solid var(--color-border);
  padding: 16px 0;
  position: sticky;
  top: 0;
  z-index: 100;
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-logo {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-primary);
  display: flex;
  align-items: center;
  gap: 8px;
}

.site-logo svg {
  flex-shrink: 0;
}

.header-badge {
  font-size: 0.7rem;
  background: var(--color-success);
  color: var(--color-white);
  padding: 2px 8px;
  border-radius: 10px;
  font-weight: 500;
}

/* ========== Hero ========== */
.hero {
  text-align: center;
  padding: 48px 0 32px;
}

.hero h1 {
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: 800;
  color: var(--color-text);
  margin-bottom: 12px;
  letter-spacing: -0.02em;
}

.hero p {
  font-size: 1.05rem;
  color: var(--color-text-secondary);
  max-width: 600px;
  margin: 0 auto 16px;
}

.privacy-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: #e6f4ea;
  color: var(--color-success);
  padding: 6px 16px;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 500;
}

.privacy-badge svg { flex-shrink: 0; }

/* ========== Cards ========== */
.card {
  background: var(--color-white);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  padding: 24px;
  margin-bottom: 24px;
  border: 1px solid var(--color-border);
}

.card h2 {
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.card h2 svg {
  color: var(--color-primary);
  flex-shrink: 0;
}

/* ========== Drop Zone ========== */
.drop-zone {
  border: 2px dashed var(--color-border);
  border-radius: var(--radius-lg);
  padding: 40px 20px;
  text-align: center;
  cursor: pointer;
  transition: all var(--transition);
  background: var(--color-primary-light);
  position: relative;
}

.drop-zone:hover,
.drop-zone.drag-over {
  border-color: var(--color-primary);
  background: #d2e3fc;
}

.drop-zone.processing {
  opacity: 0.7;
  pointer-events: none;
}

.drop-zone-icon {
  margin-bottom: 12px;
  color: var(--color-primary);
}

.drop-zone h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--color-text);
}

.drop-zone p {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
}

.drop-zone .supported-formats {
  margin-top: 12px;
  font-size: 0.75rem;
  color: var(--color-text-secondary);
}

#file-input { display: none; }

/* ========== Tabs ========== */
.tabs {
  display: flex;
  border-bottom: 2px solid var(--color-border);
  margin-bottom: 20px;
}

.tab-btn {
  padding: 10px 20px;
  font-size: 0.95rem;
  font-weight: 600;
  border: none;
  background: none;
  color: var(--color-text-secondary);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  transition: all var(--transition);
  font-family: var(--font-body);
}

.tab-btn:hover { color: var(--color-primary); }

.tab-btn.active {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

.tab-content { display: none; }
.tab-content.active { display: block; }

/* ========== Paste Area ========== */
.paste-area textarea {
  width: 100%;
  min-height: 160px;
  padding: 12px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-family: var(--font-mono);
  font-size: 0.9rem;
  resize: vertical;
  line-height: 1.5;
  transition: border-color var(--transition);
}

.paste-area textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(26, 115, 232, 0.15);
}

/* ========== Paste Result ========== */
.paste-result-header {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
  padding: 8px 0;
}

.paste-actions {
  display: flex;
  gap: 8px;
  margin-top: 12px;
}

/* ========== File List ========== */
.file-table-wrapper {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.file-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

.file-table th {
  text-align: left;
  padding: 10px 12px;
  font-weight: 600;
  color: var(--color-text-secondary);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  border-bottom: 2px solid var(--color-border);
  white-space: nowrap;
}

.file-table td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--color-border);
  vertical-align: middle;
}

.file-table tr:hover {
  background: var(--color-primary-light);
}

.file-name-cell {
  max-width: 200px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  font-weight: 500;
}

.action-cell {
  white-space: nowrap;
}

.batch-actions {
  display: flex;
  gap: 8px;
  margin-top: 16px;
  align-items: center;
}

/* ========== Badges ========== */
.encoding-badge {
  display: inline-block;
  padding: 2px 10px;
  background: var(--color-primary-light);
  color: var(--color-primary);
  border-radius: 4px;
  font-size: 0.8rem;
  font-weight: 600;
  font-family: var(--font-mono);
}

.confidence-badge {
  display: inline-block;
  padding: 2px 10px;
  border: 1.5px solid;
  border-radius: 4px;
  font-size: 0.8rem;
  font-weight: 600;
}

/* ========== Preview Modal ========== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.modal-overlay.hidden { display: none; }

.modal-content {
  background: var(--color-white);
  border-radius: var(--radius-lg);
  width: 100%;
  max-width: 800px;
  max-height: 80vh;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-lg);
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  border-bottom: 1px solid var(--color-border);
}

.modal-header h3 {
  font-size: 1rem;
  font-weight: 600;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.modal-body {
  flex: 1;
  overflow-y: auto;
  padding: 0;
}

.preview-container {
  display: flex;
  min-height: 300px;
}

.preview-pane {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.preview-pane + .preview-pane {
  border-left: 1px solid var(--color-border);
}

.preview-pane-header {
  padding: 8px 16px;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-text-secondary);
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
}

.preview-content {
  flex: 1;
  padding: 12px 16px;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.5;
  white-space: pre-wrap;
  word-break: break-all;
  overflow-y: auto;
  margin: 0;
  background: none;
}

.modal-footer {
  padding: 12px 20px;
  border-top: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.modal-footer label {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  font-weight: 500;
}

.modal-footer select {
  padding: 4px 8px;
  border: 1px solid var(--color-border);
  border-radius: 4px;
  font-size: 0.85rem;
  background: var(--color-white);
}

/* ========== Buttons ========== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 8px 16px;
  border: none;
  border-radius: var(--radius);
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition);
  font-family: var(--font-body);
  white-space: nowrap;
  min-height: 36px;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

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

.btn-primary:hover:not(:disabled) {
  background: var(--color-primary-hover);
}

.btn-outline {
  background: transparent;
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
}

.btn-outline:hover:not(:disabled) {
  background: var(--color-bg);
  color: var(--color-text);
}

.btn-preview {
  background: none;
  color: var(--color-primary);
  padding: 4px 8px;
}

.btn-preview:hover { background: var(--color-primary-light); }

.btn-download {
  background: none;
  color: var(--color-success);
  padding: 4px 8px;
}

.btn-download:hover { background: #e6f4ea; }

.btn-remove {
  background: none;
  color: var(--color-error);
  padding: 4px 8px;
}

.btn-remove:hover { background: #fce8e6; }

.btn-batch {
  padding: 10px 24px;
  font-size: 0.95rem;
}

.btn-close {
  background: none;
  border: none;
  color: var(--color-text-secondary);
  cursor: pointer;
  padding: 4px;
  border-radius: 4px;
  transition: background var(--transition);
}

.btn-close:hover {
  background: var(--color-bg);
  color: var(--color-text);
}

/* ========== Tutorial Section ========== */
.tutorial-section {
  margin-top: 32px;
  padding-top: 32px;
  border-top: 2px solid var(--color-border);
}

.tutorial-section > h2 {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 24px;
}

.tutorial-item {
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  margin-bottom: 8px;
  overflow: hidden;
  background: var(--color-white);
}

.tutorial-header {
  padding: 14px 16px;
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: background var(--transition);
}

.tutorial-header:hover { background: var(--color-bg); }

.tutorial-header::after {
  content: '';
  border: solid var(--color-text-secondary);
  border-width: 0 2px 2px 0;
  padding: 3px;
  transform: rotate(45deg);
  transition: transform var(--transition);
  flex-shrink: 0;
  margin-left: 12px;
}

.tutorial-item.active .tutorial-header::after {
  transform: rotate(-135deg);
}

.tutorial-body {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
}

.tutorial-item.active .tutorial-body {
  max-height: 2000px;
}

.tutorial-body-inner {
  padding: 0 16px 16px;
  font-size: 0.9rem;
  line-height: 1.7;
  color: var(--color-text-secondary);
}

.tutorial-body-inner h4 {
  font-weight: 600;
  color: var(--color-text);
  margin: 12px 0 6px;
  font-size: 0.9rem;
}

.tutorial-body-inner code {
  background: var(--color-bg);
  padding: 1px 6px;
  border-radius: 3px;
  font-family: var(--font-mono);
  font-size: 0.85rem;
}

.tutorial-body-inner pre {
  background: #1e1e1e;
  color: #d4d4d4;
  padding: 12px;
  border-radius: var(--radius);
  overflow-x: auto;
  margin: 8px 0;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1.5;
}

.tutorial-body-inner ul,
.tutorial-body-inner ol {
  padding-left: 20px;
  margin: 6px 0;
}

.tutorial-body-inner li { margin: 4px 0; }

/* ========== Toast ========== */
#toast-container {
  position: fixed;
  top: 20px;
  right: 20px;
  z-index: 2000;
  display: flex;
  flex-direction: column;
  gap: 8px;
  max-width: 360px;
}

.toast {
  padding: 12px 16px;
  border-radius: var(--radius);
  font-size: 0.85rem;
  font-weight: 500;
  box-shadow: var(--shadow-md);
  animation: slideIn 0.3s ease;
  word-break: break-word;
}

.toast-success { background: #e6f4ea; color: #1e7e34; }
.toast-warning { background: #fef7e0; color: #b45309; }
.toast-error { background: #fce8e6; color: #c5221f; }
.toast-info { background: #e8f0fe; color: var(--color-primary); }

.toast.fade-out {
  animation: fadeOut 0.3s ease forwards;
}

@keyframes slideIn {
  from { transform: translateX(100%); opacity: 0; }
  to { transform: translateX(0); opacity: 1; }
}

@keyframes fadeOut {
  from { opacity: 1; }
  to { opacity: 0; }
}

/* ========== Footer ========== */
.site-footer {
  text-align: center;
  padding: 24px 0;
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  border-top: 1px solid var(--color-border);
  margin-top: 32px;
}

/* ========== Ad Section ========== */
.ad-section {
  margin: 24px 0;
  text-align: center;
  min-height: 90px;
}

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

/* ========== Responsive ========== */
@media (max-width: 767px) {
  .hero h1 { font-size: 1.5rem; }
  .hero p { font-size: 0.95rem; }

  .card { padding: 16px; }

  .drop-zone { padding: 24px 16px; }

  .preview-container { flex-direction: column; }
  .preview-pane + .preview-pane { border-left: none; border-top: 1px solid var(--color-border); }

  .file-table { font-size: 0.8rem; }
  .file-table th, .file-table td { padding: 8px; }
  .file-name-cell { max-width: 120px; }

  .batch-actions { flex-direction: column; }
  .batch-actions .btn { width: 100%; }

  .modal-content { max-height: 90vh; }

  .paste-actions { flex-direction: column; }
  .paste-actions .btn { width: 100%; }

  .btn { min-height: 44px; }
}

@media (min-width: 768px) {
  .hero h1 { font-size: 2.25rem; }
}

/* ========== Scrollbar ========== */
.preview-content::-webkit-scrollbar,
.file-table-wrapper::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

.preview-content::-webkit-scrollbar-thumb,
.file-table-wrapper::-webkit-scrollbar-thumb {
  background: var(--color-border);
  border-radius: 3px;
}

.preview-content::-webkit-scrollbar-track,
.file-table-wrapper::-webkit-scrollbar-track {
  background: transparent;
}