/*
https://abctool.info/mathjax-editor/en/
*/
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --bg-color: #f8fafc;
  --card-bg: #ffffff;
  --text-main: #1e293b;
  --text-muted: #64748b;
  --border-color: #e2e8f0;
  --primary-color: #2563eb;
  --primary-hover: #1d4ed8;
  --primary-light: #eff6ff;
  --danger-color: #ef4444;
  --danger-hover: #dc2626;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --transition: all 0.2s ease;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-main);
  line-height: 1.6;
  padding: 24px 16px;
  min-height: 100vh;
}

.container {
  max-width: 1080px;
  margin: 0 auto;
}

/* Top Navigation Bar */
.top-nav-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 24px;
  padding: 10px 16px;
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
}

.top-nav-left, .top-nav-right {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
}

.top-brand-link {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-main);
  text-decoration: none;
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  transition: var(--transition);
}

.top-brand-link:hover {
  background-color: #f1f5f9;
  color: var(--primary-color);
}

.top-brand-badge {
  background-color: var(--primary-light);
  color: var(--primary-color);
  border: 1px solid #bfdbfe;
}

.top-brand-badge:hover {
  background-color: var(--primary-color);
  color: #ffffff;
  border-color: var(--primary-color);
}

.top-lang-nav {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 4px;
}

.top-lang-link {
  font-size: 0.8125rem;
  color: var(--text-muted);
  text-decoration: none;
  padding: 3px 8px;
  border-radius: var(--radius-sm);
  transition: var(--transition);
}

.top-lang-link:hover {
  color: var(--primary-color);
  background-color: var(--primary-light);
}

.top-lang-link.active {
  font-weight: 600;
  color: var(--primary-color);
  background-color: var(--primary-light);
}

.top-nav-divider {
  width: 1px;
  height: 16px;
  background-color: var(--border-color);
  margin: 0 4px;
}

/* Header */
.app-header {
  text-align: center;
  margin-bottom: 32px;
}

.app-title {
  font-size: 2rem;
  font-weight: 700;
  color: var(--text-main);
  letter-spacing: -0.02em;
  margin-bottom: 8px;
}

.app-subtitle {
  font-size: 1rem;
  color: var(--text-muted);
}

/* Preset Examples */
.preset-section {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.preset-label {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-muted);
}

.preset-tags {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.preset-btn {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  font-size: 0.8125rem;
  padding: 4px 12px;
  border-radius: 9999px;
  cursor: pointer;
  transition: var(--transition);
}

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

/* Main Grid Layout */
.editor-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

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

/* Panels */
.panel {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  transition: var(--transition);
}

.panel:hover {
  box-shadow: var(--shadow-md);
}

.panel-header {
  padding: 14px 20px;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
  background-color: #fafbfc;
}

.panel-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-main);
}

.panel-actions {
  display: flex;
  gap: 8px;
}

.panel-body {
  padding: 20px;
  flex: 1;
  display: flex;
  flex-direction: column;
}

/* Inputs & Textarea */
.latex-textarea {
  width: 100%;
  height: 260px;
  padding: 14px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  font-size: 0.95rem;
  color: var(--text-main);
  background-color: #fdfdfd;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  resize: vertical;
  outline: none;
  transition: var(--transition);
  line-height: 1.5;
}

.latex-textarea:focus {
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
  background-color: #ffffff;
}

/* Preview Output */
.preview-container {
  min-height: 260px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  background-color: #ffffff;
  border: 1px dashed var(--border-color);
  border-radius: var(--radius-md);
  overflow-x: auto;
  text-align: center;
}

.preview-output {
  font-size: 1.35rem;
  color: var(--text-main);
  max-width: 100%;
}

.preview-output svg {
  max-width: 100%;
  height: auto;
}

.empty-tip {
  color: var(--text-muted);
  font-size: 0.9rem;
  font-style: italic;
}

.error-message {
  color: var(--danger-color);
  background-color: #fef2f2;
  border: 1px solid #fee2e2;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  margin-top: 12px;
  display: none;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 6px 14px;
  font-size: 0.875rem;
  font-weight: 500;
  border-radius: var(--radius-sm);
  cursor: pointer;
  border: 1px solid transparent;
  transition: var(--transition);
  text-decoration: none;
}

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

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

.btn-secondary {
  background-color: #ffffff;
  border-color: var(--border-color);
  color: var(--text-main);
}

.btn-secondary:hover {
  background-color: #f1f5f9;
  border-color: #cbd5e1;
}

.btn-danger {
  background-color: #ffffff;
  border-color: var(--border-color);
  color: var(--danger-color);
}

.btn-danger:hover {
  background-color: #fef2f2;
  border-color: #fca5a5;
}

.btn-sm {
  padding: 4px 10px;
  font-size: 0.8125rem;
}

/* Footer / Meta info */
.footer-info {
  margin-top: 40px;
  padding-top: 24px;
  border-top: 1px solid var(--border-color);
  text-align: center;
  color: var(--text-muted);
  font-size: 0.875rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.footer-links {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 16px;
}

.footer-link {
  color: var(--primary-color);
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition);
}

.footer-link:hover {
  color: var(--primary-hover);
  text-decoration: underline;
}

.footer-divider {
  color: var(--border-color);
}


/* Toast */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background-color: #1e293b;
  color: #ffffff;
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  opacity: 0;
  pointer-events: none;
  transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
  box-shadow: var(--shadow-lg);
  z-index: 999;
}

.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* Feature & Intro Sections */
.info-section {
  margin-top: 48px;
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.card {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 28px;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.card:hover {
  box-shadow: var(--shadow-md);
}

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

.section-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
  display: flex;
  align-items: center;
  gap: 8px;
}

.section-desc {
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 20px;
}

.link-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: linear-gradient(135deg, #2563eb 0%, #1d4ed8 100%);
  color: #ffffff;
  font-size: 0.925rem;
  font-weight: 600;
  padding: 10px 20px;
  border-radius: var(--radius-md);
  text-decoration: none;
  border: 1px solid rgba(255, 255, 255, 0.1);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.25), 0 1px 2px rgba(0, 0, 0, 0.05);
  transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
  letter-spacing: -0.01em;
}

.link-btn:hover {
  background: linear-gradient(135deg, #1d4ed8 0%, #1e40af 100%);
  color: #ffffff;
  transform: translateY(-2px);
  box-shadow: 0 8px 18px rgba(37, 99, 235, 0.35), 0 2px 4px rgba(0, 0, 0, 0.08);
}

.link-btn:active {
  transform: translateY(0);
  box-shadow: 0 2px 6px rgba(37, 99, 235, 0.2);
}

.feature-item-wide {
  grid-column: 1 / -1;
}

.lang-links-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 10px;
}

.lang-tag {
  display: inline-flex;
  align-items: center;
  padding: 4px 12px;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-main);
  background-color: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: 9999px;
  text-decoration: none;
  transition: var(--transition);
}

.lang-tag:hover {
  background-color: var(--primary-light);
  border-color: var(--primary-color);
  color: var(--primary-color);
  transform: translateY(-1px);
  box-shadow: 0 2px 5px rgba(37, 99, 235, 0.12);
}


.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 16px;
}

.feature-item {
  background-color: #f8fafc;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.feature-item-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-main);
  display: flex;
  align-items: center;
  gap: 8px;
}

.feature-item-desc {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.5;
}

.demo-feature-list {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 14px;
}

.demo-feature-list li {
  background-color: #f8fafc;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 14px 16px;
  font-size: 0.875rem;
  color: var(--text-main);
  line-height: 1.5;
}

.demo-feature-list strong {
  color: var(--primary-color);
  display: block;
  margin-bottom: 4px;
  font-size: 0.9rem;
}